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    Roller coaster with cold molecules

    Date:
    26
    Wednesday
    February
    2025
    Colloquium
    Time: 11:00-12:15
    Title: Special Chemistry Colloquium
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Ed Narevicius
    Abstract: Quantum effects play a central role in low temperature collisions. Particularly ... Read more Quantum effects play a central role in low temperature collisions. Particularly important is the formation of metastable scattering resonances that lead to temporary trapping of the colliding particles. Observation of such states has long been limited to laser cooled species, leaving chemically relevant molecules such as hydrogen out of reach. I will present our method that uses high magnetic field gradients to merge two molecular beams circumventing the laser cooling step. It allows us to perform collisions with molecular hydrogen at energies reaching 0.001 K. I will show the fingerprints of quantum resonances on observable properties and also highlight the astounding effect of the internal molecular structure and symmetry. Finally, I will discuss how a moving magnetic trap decelerator can serve as stepping stone towards the direct laser cooling of diatomic radicals.
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    Roller coaster with cold molecules Colloquium website

    How we make superconducting qubits live longer

    Date:
    19
    Wednesday
    February
    2025
    Lecture / Seminar
    Time: 12:30-14:00
    Title: Spotlight on Science lecture sponsored by the Staff Scientists Council
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Fabien Lafont
    Contact: mark.a.iron@weizmann.ac.il
    Abstract: Classical computers use stable and long-lived units of information, called bits, ... Read more Classical computers use stable and long-lived units of information, called bits, to perform computations. In contrast, quantum computers rely on qubits. The downside is that qubits are intrinsically much more prone to error. Two of the biggest challenges in building a practical quantum computer are extending the lifetime of qubits and better detection of errors. In this seminar, I will present our recent work on improving by an order of magnitude the coherence time of a superconducting qubit. A key aspect of this breakthrough was the creation of a large Schrödinger cat state with more than 1,000 photons, which can be used for error correction in quantum systems. In the second part of the talk, I will introduce a novel method for real-time error detection, where we continuously monitor the state of a superconducting element to detect and correct qubit dephasing as it occurs. These developments are important steps towards improving the reliability and performance of quantum systems.
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    Climate and Solar Variability: A Critical Evaluation

    Date:
    09
    Sunday
    February
    2025
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Nathan Steiger
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: It has been claimed that solar variability is the largest driver of climatic var ... Read more It has been claimed that solar variability is the largest driver of climatic variability across thePhanerozoic eon and that it accounts for ½ to ⅔ of20th century warming. Apparent evidence insupport of these claims has been mustered frommodeling work along with paleoclimatic, oceanographic, and other observational datasets.Here I will show that this research fails to replicate. I additionally find that many studies claiming tosupport a strong solar-climate link suffer from fundamental statistical and conceptual errors thatinvalidate their results.
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    In honor of the 100th birthday of Prof. Yigal Talmi

    Date:
    30
    Thursday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Title: Factorization and Universality in Nuclear Physics
    Location: Physics Weissman Auditorium
    Lecturer: Prof. Nir Barnea
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Abstract: The study of dilute, strongly interacting quantum gases revealsuniversal propert ... Read more The study of dilute, strongly interacting quantum gases revealsuniversal properties that transcend the specifics of individualsystems. These features arise from their short-range behaviorand are encapsulated in a key quantity called the “contact”, whichquantifies the probability of two particles being in close proximity.In this talk, I will introduce the contact theory and its extension tonuclear and molecular systems beyond the zero-range limit. I willdemonstrate its applicability in analyzing nuclear electronscattering and photo absorption reactions.Additionally, I will discuss how mean-field approximations, such asthe nuclear shell model, can effectively estimate the contact,offering valuable insights into the underlying physics.
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    Physics Colloquium

    Date:
    27
    Monday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Title: Programmable quantum many-body physics with Rydberg atom arrays
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Dr. Tom Manovitz
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Programmable quantum platforms have emerged as powerful tools for studying quant ... Read more Programmable quantum platforms have emerged as powerful tools for studying quantum many-body phenomena, with applications ranging from condensed matter and high energy physics to quantum algorithms. In this talk, I will discuss recent developments involving programmable Rydberg atom arrays, which allow for precise and coherent control of hundreds of atoms in two dimensions, along with individual addressability and reconfigurable geometry. First, I will describe explorations of ordering dynamics in a quantum magnet following a quantum phase transition. Using individual atom control, we uncover the interplay of quantum criticality and non-equilibrium phenomena, and observe long-lived oscillations of the order parameter akin to an amplitude (“Higgs”) mode, with interesting implications near the quantum critical point. I will then describe the digital realization of the Kitaev honeycomb model, including observation of an exotic non-Abelian spin-liquid, as well as the use of topological order to design a programmable fermionic simulator. These measurements introduce new avenues for the study of quantum criticality and fermionic models, respectively. Finally, I will briefly discuss future opportunities in explorations of quantum many-body physics with atom arrays, with emphasis on new frontiers in the study of quantum criticality.
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    Physics Colloquium

    Date:
    23
    Thursday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Title: It takes two to tango: The physics of heterogeneous bacterial active matter systems
    Location: Physics Weissman Auditorium
    Lecturer: Prof. Joel Stavans
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Non-equilibrium active matter systems often exhibit self-organized, collective m ... Read more Non-equilibrium active matter systems often exhibit self-organized, collective motion that can give rise to the emergence of coherent spatial structures. Prime examples covering many length scales range from mammal herds, fish schools and bird flocks, to insect and robot swarms. Despite significant advances in understanding the behavior of homogeneous systems in the last decades, little is known about the self-organization and dynamics of heterogeneous active matter. I will present results of bioconvection experiments with multispecies suspensions of wild-type bacteria from the hyper-diverse bacterial communities of Cuatro Ciénegas, Coahuila, whose origin dates back to the pre-Cambrian. Under oxygen gradients, these bacteria swim in auto-organized, directional flows, whose spatial scales exceed the cell size by orders of magnitude, demonstrating a plethora of amazing dynamical behaviors, including segregation. I will present evidence supporting the notion that the mechanisms giving rise to these complex behaviors are predominantly physical, and not a result of biological interactions. This research significantly advances our understanding of both heterogeneity in active matter, as well as in the dynamics of complex microbial ecological communities, bringing profound insights into their spatial organization and collective behavior.
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    Chemical and Biological Physics Dept. -Guest Seminar

    Date:
    15
    Wednesday
    January
    2025
    Lecture / Seminar
    Time: 13:00-14:00
    Location: perlman
    Lecturer: Dr. Natalie Fardian-Melamed, Columbia University, NY, USA
    Abstract: Mechanical force is a critical feature for most physical processes, and remote m ... Read more Mechanical force is a critical feature for most physical processes, and remote measure of mechanical signals with high force sensitivity and spatial resolution is crucial for progress in fields as diverse as robotics, biophysics, civil engineering, and medicine. Existing nanoscale remote force sensors, however, are very limited in the dynamic range of forces they can detect, and are rarely compatible with subsurface operation, restricting sensor applicability [1]. In this talk, I will describe how we leverage the extreme optical nonlinearity offered by photon-avalanche [2], and its susceptibility to steep change due to minute changes in the environment – to create nanoscale force sensors that can be addressed remotely by continuous-wave, deeply-penetrating, infrared light, and can detect picoNewton to microNewton forces with a dynamic range spanning more than four orders of magnitude [3]. Using atomic force microscopy coupled with single-nanoparticle optical spectroscopy, we characterize the mechano-optics of different Tm3+-doped avalanching upconverting nanoparticles on a single particle level, to rationally design force sensors with different modalities of force-dependent optical readout, including mechanobrightening and mechanochromism. By manipulating the interionic distances and hence energy transfer pathways within the nanosensors by application of force, we demonstrate exceptional mechanical sensitivity coupled with high single-particle brightness, over multiple scales of force. The adaptability of these nanoscale optical force sensors, along with their multiscale sensing capability, enable operation in the dynamic and versatile environments present in diverse, real-world structures spanning biological organisms to nanoelectromechanical systems.
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    Emerging Quantum Pheneomena in Nonlinear Nanophotonics: Toward New Regimes of Light-Matter Interactions

    Date:
    12
    Sunday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Location: Physics Library
    Lecturer: Dr. Eran Lustig
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Nanophotonics is at the forefront of research and development in scalable quantu ... Read more Nanophotonics is at the forefront of research and development in scalable quantum technologies,ranging from quantum sensing to quantum computing. Traditionally, inherently weak photon-photonand photon-atom interactions in dielectric materials pose significant challenges to fully exploiting thepotential of these platforms. However, recent advances in the fabrication of nonlinear microresonatorswith nanometric features have allowed for the enhancement of all-optical interactions,necessitating new approaches to generating, controlling, and measuring quantum light.In this seminar, I will delve into unexplored regimes at the intersection of nonlinear and quantumoptics. I will begin by showcasing our latest advancements in developing integrated microresonatorsin thin-film 4H-Silicon Carbide. This innovation enables nonlinear photonics, quantum optics, andcollective quantum emitter excitations on the same platform. Following this, I will present ourexperimental demonstration of quadrature lattices of the quantum vacuum. This work shows howpulses that spontaneously emerge in microresonators can generate lattice dynamics of the quantumvacuum and how we can exert control over these dynamics.I will then discuss the broader implications of our findings, including enhanced interactions withquantum emitters, and ultrafast nonlinear quantum nanophotonics, which enable nonlinearinteractions at the single photon level. These outcomes pave the way toward new regimes of lightmatterinteractions that are enabled on scalable photonic microchips, with transformativeimplications for fundamental physics and quantum applications.
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    Black Holes in Galaxies: Experimental Evidence & Cosmic Evolution

    Date:
    09
    Thursday
    January
    2025
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Reinhard Genzel
    Organizer: Department of Particle Physics and Astrophysics
    Contact: eti.shalem@weizmann.ac.il
    Abstract: About a century after Albert Einstein's presentation of General Relativity and K ... Read more About a century after Albert Einstein's presentation of General Relativity and Karl Schwarzschild's first solution, have three experimental techniques made remarkable progress in proving the existence of the Schwarzschild/Kerr black hole solution. I will describe the impressive progress of high resolution near-infrared and radio imaging and interferometry, and of precision measurements of gravitational waves in the Galactic Center and other galaxies. I will then discuss what we now know about the cosmic co-evolution and growth of galaxies and black holes, and finish with the riddle of massive black holes detected by JWST only a few hundred Myrs after the Big Bang.
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    The Clore Center for Biological Physics

    Date:
    05
    Sunday
    January
    2025
    Lecture / Seminar
    Time: 13:15-14:30
    Title: The Analog Computer — a "Comeback"?
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Prof. Oren Raz
    Organizer: Clore Center for Biological Physics
    Contact: debbie.hen@weizmann.ac.il
    Abstract: In the last decade there have been several efforts to use physical systems as 'p ... Read more In the last decade there have been several efforts to use physical systems as 'physical computers': D-Wave is using super-conducting qubits as an adiabatic quantum (or non-quantum?) computer, the Israeli company Light-Solver (ex Davidson group) tries to use lasers in finding optimal solutions to optimization problems, HP is developing memristor computation, 'Natural Computing' is developing a chip that is based on thermal computin,  companies like Toshiba and Fujitsu are commercializing products like Bifurcation machines' and Digital annealers', and so on...  Are we indeed seeing the `comeback' of analog computers? In the talk I will discuss the physical ideas behind these machines and try to provide some intuition and understanding on their advantages and disadvantages. FOR THE LATEST UPDATES AND CONTENT ON SOFT MATTER AND BIOLOGICAL PHYSICS AT THE WEIZMANN, VISIT OUR WEBSITE: https://www.biosoftweizmann.com/
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    Midrasha on Groups Seminar

    Date:
    09
    Monday
    December
    2024
    Lecture / Seminar
    Time: 14:15-16:00
    Title: On the quantum unique ergodicity conjecture for hyperbolic arithmetic manifolds
    Location: Jacob Ziskind Building
    Lecturer: Zvi Shem-Tov
    Organizer: Department of Mathematics
    Contact: hany.kochavi@weizmann.ac.il
    Abstract: Suppose $u_j$ is an orthonormal basis of eigenfunctions of the Laplacian on a co ... Read more Suppose $u_j$ is an orthonormal basis of eigenfunctions of the Laplacian on a compact Riemannian manifold, and consider the probability measures $|u_j|^2 dvol$. The quantum ergodicity theorem of Shnirelman, Zelditch and Colin de Verdiere, states that if the geodesic flow on the manifold is ergodic then there is a density one subsequence of these measures that equidistributes. What about the remaining eigenfunctions? The quantum unique ergodicity conjecture of Rudnick and Sarnak states that for hyperbolic manifolds (or more generally for negatively curved manifolds), any sequence of measures as above equidistributes.  In 2006 Lindenstrauss proved that this is true for Hecke—Maass forms on congruence surfaces. These are eigenfunctions of both the Laplacian and the Hecke operators, which are discrete averaging operators coming from the arithmetic structure of the manifold.  We will discuss our extensions of Lindenstrauss’ results to the three and (partially) four dimensional cases. One of the challenges that arise in the higher dimensional case is to rule out concentration of measure on totally geodesic submanifolds. We will focus on this issue and our new methods for showing non-concentration.  Based on joint works with Alexandre de Faveri and Lior Silberman.
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    Physics Colloquium

    Date:
    05
    Thursday
    December
    2024
    Colloquium
    Time: 11:15-12:30
    Title: IS EARTH EXCEPTIONAL?
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Organizer: Department of Particle Physics and Astrophysics
    Abstract: The questions “How did life on Earth begin?” and “Are we alone in the univ ... Read more The questions “How did life on Earth begin?” and “Are we alone in the universe?” are arguably two of the most intriguing in science. While until recently these questions tended to be relegated to the “too difficult” box, the attempts to answer them have now become extraordinarily vibrant and dynamic frontiers of science. I will describe how the quest for cosmic life follows two parallel, independent lines of research: cutting-edge laboratory studies aimed at determining whether life can emerge from pure chemistry, and advanced astronomical observations searching for signs of life on other planets and moons in the solar system and around stars other than the Sun. I will examine how using knowledge acquired through ingenious chemical experimentation, geological studies, advanced astronomical observations, and imaginative theorizing researchers have managed to delineate a plausible pathway leading from the formation of the Earth to the appearance of the early biological cells.  
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    Physics Colloquium Colloquium website

    Physics Colloquium

    Date:
    05
    Thursday
    December
    2024
    Colloquium
    Time: 11:15-12:30
    Title: IS EARTH EXCEPTIONAL?
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Livio Mario
    Organizer: Department of Particle Physics and Astrophysics
    Abstract: The questions “How did life on Earth begin?” and “Are we alone in the univ ... Read more The questions “How did life on Earth begin?” and “Are we alone in the universe?” are arguably two of the most intriguing in science. While until recently these questions tended to be relegated to the “too difficult” box, the attempts to answer them have now become extraordinarily vibrant and dynamic frontiers of science. I will describe how the quest for cosmic life follows two parallel, independent lines of research: cutting-edge laboratory studies aimed at determining whether life can emerge from pure chemistry, and advanced astronomical observations searching for signs of life on other planets and moons in the solar system and around stars other than the Sun. I will examine how using knowledge acquired through ingenious chemical experimentation, geological studies, advanced astronomical observations, and imaginative theorizing researchers have managed to delineate a plausible pathway leading from the formation of the Earth to the appearance of the early biological cells.  
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    Physics Colloquium Colloquium website

    Physics Colloquium

    Date:
    28
    Thursday
    November
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Erasure detection with superconducting qubits
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Alex Retzker
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Light Refreshments at 11:00

    Special Guest Seminar

    Date:
    20
    Wednesday
    November
    2024
    Lecture / Seminar
    Time: 10:00-11:00
    Title: A formalism for Arithmetic Quantum Field Theory
    Location: Jacob Ziskind Building
    Lecturer: Nadav Gropper
    Organizer: Department of Mathematics
    Contact: hany.kochavi@weizmann.ac.il
    Abstract: Arithmetic Topology, first pioneered by Mazur in 1963, draws analogies between n ... Read more Arithmetic Topology, first pioneered by Mazur in 1963, draws analogies between number theory and low dimensional topology, primes and knots, and surface and p-adic fields. On one hand, quantum field theory can be expressed in terms of the geometry and topology of low-dimensional manifolds, on the level of states (via the Atiyah-Segal) and on the level of observables (via the Beilinson–Drinfeld). Thus, as first proposed by Minhyong Kim (in his Arithmetic Chern-Simons Theory), one can try and find arithmetic versions of quantum field theoretic ideas. In the talk, I will introduce a new general framework for (d 1)-dimensional arithmetic TQFT. I will explain the classification of such TQFTS for the (1 1)-dimensional case, in terms of Frobenius algebras with some extra structure, this enables us to study pro-p cobordisms and TQFTs for p-adic fields and surfaces at the same time.  If time permits, I will outline how we use the above to compute a Dijkgraaf-Witten like invariants for G, a finite p-group, to get formulas for counting covers of Surfaces/p-adic fields with Galois group G (these formulas are similar to the ones given by Mednykh for surfaces using TQFTs, and by Masakazu Yamagishi using a more algebraic approach). The talk is based on joint work with Oren Ben-Bassat. No prior knowledge of Topological Quantum Field Theory or Arithmetic Topology will be assumed.
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    Physics Colloquium

    Date:
    05
    Thursday
    September
    2024
    Colloquium
    Time: 11:15-12:30
    Title: New era in dark matter searches, the dawn of the nuclear clocks
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Gilad Perez,Prof. Gilad Perez
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: After a brief introduction related to ultralight (pseudo) scalar dark matter, we ... Read more After a brief introduction related to ultralight (pseudo) scalar dark matter, we shall describe the current status of searches for ultralight dark matter (UDM). We explain why modern clocks can be used to search for both scalar and axion dark matter fields. We review existing and new types of well-motivated models of UDM and argue that they all share one key ingredient - their dominant coupling is to the QCD/nuclear sector. This is very exciting as we are amidst a revolution in the field of dark matter searches as laser excitation of Th-229 with effective precision of 1:10^13 has been recently achieved, which as we show, is already probing uncharted territory of models. Furthermore, Th-229-based nuclear clock can potentially improve the sensitivity to physics of dark matter and beyond by factor of 10^10! It has several important implications to be discussed.
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    Foundations of Computer Science Seminar

    Date:
    08
    Monday
    July
    2024
    Lecture / Seminar
    Time: 11:15-12:15
    Title: Quantum Algorithms in a Superposition of Spacetimes
    Location: Jacob Ziskind Building
    Lecturer: Omri Shmueli
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: Quantum computers are expected to revolutionize our ability to process informati ... Read more Quantum computers are expected to revolutionize our ability to process information. The advancement from classical to quantum computing is a product of our advancement from classical to quantum physics -- the more our understanding of the universe grows, so does our ability to use it for computation. A natural question that arises is, what will physics allow in the future? Can more advanced theories of physics increase our computational power, beyond quantum computing? An active field of research in physics studies theoretical phenomena outside the scope of explainable quantum mechanics, that form when attempting to combine Quantum Mechanics (QM) with General Relativity (GR) into a unified theory of Quantum Gravity (QG). QG is known to present the possibility of a quantum superposition of causal structure and event orderings. In the literature of quantum information theory, this translates to a superposition of unitary evolution orders. In this talk we will show a first example of a computational model based on models of QG, that provides an exponential speedup over standard quantum computation (under standard hardness assumptions). We define a model and complexity measure for a quantum computer that has the ability to generate a superposition of unitary evolution orders, and show that such computer is able to solve in polynomial time two well-studied problems in computer science: The Graph Isomorphism Problem and the Gap Closest Vector Problem, with gap O( n^{1.5} ).    The talk is based on https://arxiv.org/abs/2403.02937 .
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    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    June
    2024
    Lecture / Seminar
    Time: 11:15-12:15
    Title: Differentially Private Space-Efficient Algorithms for Frequency Moment Estimation in the Turnstile Model
    Location: Jacob Ziskind Building
    Lecturer: Rachel Cummings
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: hany.kochavi@weizmann.ac.il
    Abstract: The  turnstile continual release model of differential privacy captures scenari ... Read more The  turnstile continual release model of differential privacy captures scenarios where a privacy-preserving real-time analysis  is sought for a dataset evolving  through additions and deletions.  In typical applications of real-time data analysis, both the length of the stream T and the size of the universe |U| from which data come can be extremely large. This motivates the study of private algorithms in the turnstile setting using space sublinear in both T and |U|. In this paper, we give the first sublinear space differentially private algorithms for the fundamental problems of counting distinct elements and $ell_p$-frequency moment estimation in the turnstile streaming model. For counting distinct elements, our algorithm achieves O(T^{1/3}) space and additive error, and a (1 eta)-relative approximation for all eta in (0,1). Our result significantly improves upon the space requirements of the state-of-the-art for this problem in this model, which has a linear dependency in both T and |U|, while still achieving an additive error that is close to the known Omega(T^{1/4}) lower bound for arbitrary streams. This addresses an open question posed in prior work about designing low-memory mechanisms for this problem. For the more general problem of L_p-frequency moment estimation, our algorithm achieves an additive error and space of O(T^{1/3}), and a (1 eta)-relative approximation for all eta in (0,1). We also give a space lower bound for this problem, which shows that any algorithm that uses our techniques must use space Omega}(T^{1/3}). Joint work with Alessandro Epasto, Jieming Mao, Tamalika Mukherjee, Tingting Ou, and Peilin Zhong.
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    Physics colloquium

    Date:
    20
    Thursday
    June
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Stochastic resonance in polymer solution channel flow
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Victor Steinberg
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 - Coffee, tea and refreshments
    Abstract: A cooperative resonance effect in a stochastic nonlinear dynamical system subjec ... Read more A cooperative resonance effect in a stochastic nonlinear dynamical system subjected to external weak periodic forcing, called stochastic resonance (SR), has been extensively studied for the past forty years. Here I discuss the experimentally unexpected observation of SR above an elastic non-modal instability of an inertia-less channel flow of polymer solution (much more complicated than stochastic dynamical flow) due to finite-size white noise perturbations. This flow is shown to be linearly stable similar to Newtonian parallel shear flow. First, I briefly describe viscoelastic flow with curved streamlines, where linear elastic normal mode instability at the critical Weissenberg number, Wic, has been observed and characterized, and the elastic instability mechanism has been explained and experimentally validated. Furthermore, at Wi>>Wic, “elastic turbulence” (ET), a chaotic flow arising via secondary instability, is experimentally discovered, characterized and theoretically explained, while elastic instability in straight channel flow is found from the direct transition from laminar to chaotic flow in the transition flow regime is found. At the secondary instability, ET is observed, and further on the next transition to the unexpected drag reduction flow regime takes place, accompanied by elastic waves previously discovered and characterized earlier. Moreover, we propose and experimentally validate a mechanism of amplification of the wall normal fluctuating vortices by the elastic waves. The elastic waves play the key role in the energy transfer from the main flow to the wall-normal fluctuating vortices. Finally, we report on recently discovered SRs only in a limited subrange of weak elastic waves just above Wic, their characterization, and their role in the transition to a chaotic flow.
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    Physics Colloquium

    Date:
    10
    Monday
    June
    2024
    Colloquium
    Time: 11:15-12:30
    Title: OBSERVATION OF FRACTIONAL QUANTUM ANOMALOUS HALL EFFECT
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Xiaodong Xu
    Organizer: Department of Condensed Matter Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Coffee and refreshments at 11:00
    Abstract: The interplay between spontaneous symmetry breaking and topology can result in e ... Read more The interplay between spontaneous symmetry breaking and topology can result in exotic quantum states of matter. A celebrated example is the quantum anomalous Hall (QAH) effect, which exhibits an integer quantum Hall effect at zero magnetic field due to topologically nontrivial bands and intrinsic magnetism. In the presence of strong electron-electron interactions, fractional-QAH (FQAH) effect at zero magnetic field can emerge, which is a lattice analog of fractional quantum Hall effect without Landau level formation. In this talk, I will present experimental observation of FQAH effect in twisted MoTe2 bilayer, using combined magneto-optical and -transport measurements. In addition, we find an anomalous Hall state near the filling factor -1/2, whose behavior resembles that of the composite Fermi liquid phase in the half-filled lowest Landau level of a two-dimensional electron gas at high magnetic field. Direct observation of the FQAH and associated effects paves the way for researching charge fractionalization and anyonic statistics at zero magnetic field. Reference 1. Observation of Fractionally Quantized Anomalous Hall Effect, Heonjoon Park et al., Nature, https://www.nature.com/articles/s41586-023-06536-0 (2023); 2. Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2 Bilayer, Jiaqi Cai et al., Nature, https://www.nature.com/articles/s41586-023-06289-w (2023); 3. Programming Correlated Magnetic States via Gate Controlled Moiré Geometry, Eric Anderson et al., Science, https://www.science.org/doi/full/10.1126/science.adg4268 (2023).
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    AI (R)Evolution in (Quantum) Chemistry and Physics

    Date:
    10
    Monday
    June
    2024
    Colloquium
    Time: 11:00-12:15
    Title: Annual Pearlman Lecture
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Alexandre Tkatchenko
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: Learning from data has led to paradigm shifts in a multitude of disciplines, inc ... Read more Learning from data has led to paradigm shifts in a multitude of disciplines, including web, text and image search and generation, speech recognition, as well as bioinformatics. Can machine learning enable similar breakthroughs in understanding (quantum) molecules and materials? Aiming towards a unified machine learning (ML) model of molecular interactions in chemical space, I will discuss the potential and challenges for using ML techniques in chemistry and physics. ML methods can not only accurately estimate molecular properties of large datasets, but they can also lead to new insights into chemical similarity, aromaticity, reactivity, and molecular dynamics. For example, the combination of reliable molecular data with ML methods has enabled a fully quantitative simulation of protein dynamics in water (https://arxiv.org/abs/2205.08306). While the potential of machine learning for revealing insights into molecules and materials is high, I will conclude my talk by discussing the many remaining challenges.
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    AI (R)Evolution in (Quantum) Chemistry and Physics Colloquium website

    Physics Colloquium

    Date:
    06
    Thursday
    June
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Emergent Quantum Phenomena in Crystalline Multilayer Graphene
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Long Ju
    Organizer: Department of Condensed Matter Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Coffee and refreshments at 11:00
    Abstract: Condensed matter physics has witnessed emergent quantum phenomena driven by elec ... Read more Condensed matter physics has witnessed emergent quantum phenomena driven by electron correlation and topology. Such phenomena have been mostly observed in conventional crystalline materials where flat electronic bands are available. In recent years, moiré superlattices built upon two-dimensional (2D) materials emerged as a new platform to engineer and study electron correlation and topology. In this talk, I will introduce a family of synthetic quantum materials, based on crystalline multilayer graphene, as a new platform to engineer and study emergent phenomena driven by many-body interactions. This system hosts flat-bands in highly ordered conventional crystalline materials and dresses them with proximity effects enabled by rich structures in 2D van der Waals heterostructures. As a result, a rich spectrum of emergent phenomena including correlated insulators, spin/valley-polarized metals, integer and fractional quantum anomalous Hall effects, as well as superconductivities have been observed in our experiments. I will also discuss the implications of these observations for topological quantum computation. References: [1] Han, T., Lu, Z., Scuri, G. et al. Nat. Nanotechnol. 19, 181–187 (2024). [2] Han, T., Lu, Z., Scuri, G. et al. Nature 623, 41–47 (2023). [3] Han, T., Lu, Z., Yao, Y. et al. Science 384,647-651(2024). [4] Lu, Z., Han, T., Yao, Y. et al. Nature 626, 759–764 (2024). [5] Yang, J., Chen, G., Han, T. et al. Science, 375(6586), pp.1295-1299. (2022)
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    Midrasha on Groups Seminar

    Date:
    03
    Monday
    June
    2024
    Lecture / Seminar
    Time: 14:15-16:00
    Title: mod 2 cohomology, random simplicial complexes, property testing, and coboundry expansion
    Location: Jacob Ziskind Building
    Lecturer: Alex Lubotzky
    Organizer: Department of Mathematics
    Contact: hany.kochavi@weizmann.ac.il
    Details: The lecture will be frontal and also via zoom (pass: 400359)
    Abstract: We will start with an elementary introduction to mod 2 cohomology (only basic li ... Read more We will start with an elementary introduction to mod 2 cohomology (only basic linear algebra is needed). We will then see how it relates to the other topics in the title. If time permits, we will also say something about quantum error correcting codes.
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    Physics Colloquium

    Date:
    23
    Thursday
    May
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Quantum Dot Physics Using Atomic Defects in Ultrathin Tunnel Barriers
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Hadar Steinberg
    Organizer: Department of Condensed Matter Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: Quantum dots (QDs) are conducting regions which can localize few charge carriers ... Read more Quantum dots (QDs) are conducting regions which can localize few charge carriers, and where the energy spectrum is dominated by Coulomb repulsion. QDs can be as large as few hundreds of nanometers, or as small as a single molecule, their sizes depending on their physical realization – whether in two-dimensional materials, nanowires, molecular systems. In my talk I will describe our work on a new type of an atomically-sized QD, realized in defects residing in ultrathin two-dimensional insulators. These defect-dots are found in layered materials such as hexagonal Boron Nitride (hBN), which we study by their assembly into stacked devices. By using graphene electrodes, we are able to electronically couple to the QD, while allowing the QD energy to be externally tuned exploiting the penetration of electric field through graphene. A consequence of the structure of our devices is that the defect QDs are placed at atomic distance to the conductors on both sides. I will show how the presence of such energy-tunable, atomically sized QDs at nanometer proximity to other conducting systems opens new opportunities for sensitive measurements, including use of QDs as highly sensitive spectrometers [1], or as single electron transistors, unique in their sensitivity to local electric fields at the nanometer scale [2]. I will discuss our future prospects of using defect QDs as quantum sensors. References 1. Devidas, T.R., I. Keren, and H. Steinberg, Spectroscopy of NbSe2 Using Energy-Tunable Defect-Embedded Quantum Dots. Nano Letters, 2021. 21(16): p. 6931-6937. 2. Keren, I., et al., Quantum-dot assisted spectroscopy of degeneracy-lifted Landau levels in graphene. Nature Communications, 2020. 11(1): p. 3408.
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    Designing nanoparticles for biological environments: from quantum sensing to gene medicine

    Date:
    20
    Monday
    May
    2024
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Petr Cigler
    Organizer: Department of Chemical and Biological Physics
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: The use of nanoparticles in diagnostics, therapeutics and imaging has revolution ... Read more The use of nanoparticles in diagnostics, therapeutics and imaging has revolutionized these fields with new properties not available with small molecules. Nanoparticle interface provide possibilities for polyvalent and independent attachment of different molecules serving as recognition/targeting structures, optical probes, spin probes or catalysts. However, nanoparticles operating in biological environments require precise control of multiple factors related to surface chemistry and their composition. To avoid for example aggregation, off-target interactions, and protein corona formation, appropriate interface design is essential. This talk will present general nanoparticle design strategies and specific examples including nanodiamonds and lipid nanoparticles.
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    Designing nanoparticles for biological environments: from quantum sensing to gene medicine Colloquium website

    Physics Colloquium

    Date:
    16
    Thursday
    May
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Toward Autonomous “Artificial Cells” in 2D
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Roy Bar-Ziv,Weizmann Institute of Science
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: We study the assembly of programmable quasi-2D DNA compartments as “artificia ... Read more We study the assembly of programmable quasi-2D DNA compartments as “artificial cells” from the individual cellular level to multicellular communication. We will describe work on autonomous synthesis and assembly of cellular machines, collective modes of synchrony in a 2D lattice of ~1000 compartments, and a first look at the birth of proteins on a single DNA.
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    Physics colloquium

    Date:
    09
    Thursday
    May
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Synergistic progress in plasmas: from fusion to astrophysics
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Julien Fuchs
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: Over the last decade, several exciting directions have been initiated by laser-d ... Read more Over the last decade, several exciting directions have been initiated by laser-driven plasmas, e.g., compact particle accelerators, inertial fusion and laboratory astrophysics. The first has known rapid progress, in terms of current, energy, stability; fusion has gone through a historic step, with the news of ignition being achieved at NIF in 2022; and laboratory astrophysics has known also spectacular developments, demonstrating the possibility to perform fully scalable experiments relevant to various objects such as forming stars and supernovae. A particularly interesting aspect is that all these fields are strongly synergistic, i.e., that advances in one can push the others as well. I will present examples of such synergies, through recent results we have obtained in all these domains, and in particular how ultra-bright neutron beams can be developed using latest generation multi-PW lasers [1,2]. These could open interesting perspectives in terms of cargo inspection, but also for fusion plasma measurements. I will also show how fusion can benefit from external magnetization [3]. Finally, I will discuss advances in laboratory astrophysics, particularly the first-stage acceleration of ions leading to cosmic rays [4,5], understanding the universal nature of collimated outflows in the Universe [6], and probing the intricacy of 3D magnetic reconnection [7] [1] High-flux neutron generation by laser-accelerated ions from single-and double-layer targets, V Horný et al., Scientific Reports 12 (1), 19767, 2022 [2] Numerical investigation of spallation neutrons generated from petawatt-scale laser-driven proton beams, B Martinez et al., Matter and Radiation at Extremes 7 (2), 024401, 2022 [3] Dynamics of nanosecond laser pulse propagation and of associated instabilities in a magnetized underdense plasma, W. Yao et al., https://doi.org/10.48550/arXiv.2211.06036 [4] Laboratory evidence for proton energization by collisionless shock surfing, W Yao et al., Nature Physics 17 (10), 1177-1182, 2021 [5] Enhancement of the Nonresonant Streaming Instability by Particle Collisions, A Marret et al., Physical Review Letters 128 (11), 115101, 2022 [6] Laboratory disruption of scaled astrophysical outflows by a misaligned magnetic field, G Revet et al., Nature communications 12 (1), 762, 2021 [7] Laboratory evidence of magnetic reconnection hampered in obliquely interacting flux tubes, S Bolaños et al., Nature Communications 13 (1), 6426, 2022
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    Data Drought in the Humid Tropics: How to Overcome the Cloud Barrier in Greenhouse Gas Remote Sensing

    Date:
    07
    Tuesday
    May
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Yinon Bar-On
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: Quantifying land-atmosphere fluxes of carbon-dioxide (CO2) and methane (CH4) is ... Read more Quantifying land-atmosphere fluxes of carbon-dioxide (CO2) and methane (CH4) is essential for evaluating carbonclimate feedbacks. Greenhouse gas satellite missions aim to provide global observational coverage of greenhouse gas concentrations and thus improve inversions of landatmosphere exchange fluxes. However, in key regions such as the humid tropics current missions obtain very few valid measurements. Leveraging recent advances in the global analysis of high-resolution optical imagery on cloudcomputing platforms and deep learning algorithms for cloud segmentation, we quantitatively diagnose the sources for low data yields in the tropics. We find that the main cause for low data yields are frequent shallow cumulus clouds. We find that increasing the spatial resolution of observations to 200 m would increase yields by 2–3 orders of magnitude and allow regular measurements in the wet season. Thus, the key to effective tropical greenhouse gas observations likely lies in regularly acquiring high-spatial resolution data.
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    Toward Autonomous “Artificial Cells” in 2D

    Date:
    11
    Thursday
    April
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Physics colloquium
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Roy Bar-Ziv
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: We study the assembly of programmable quasi-2D DNA compartments as “artificial ... Read more We study the assembly of programmable quasi-2D DNA compartments as “artificial cells”, from the individual cellular level to multicellular communication. We will describe work on autonomous synthesis and assembly of cellular machines, collective modes of synchrony in a 2D lattice of ~1000 compartments, and a first look at the birth of proteins on a single DNA.
    Close abstract

    Chemical Exfoliation of Quantum Materials

    Date:
    10
    Wednesday
    April
    2024
    Colloquium
    Time: 11:00-12:15
    Title: Special Colloquium
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Leslie M. Schoop
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: A large portion of research in 2D materials is limited to mechanical exfoliation ... Read more A large portion of research in 2D materials is limited to mechanical exfoliation of van der Waals (vdW) materials. Chemical exfoliation is a relatively under-utilized route for preparing ultra-thin quantum materials, but it accesses 2D materials that cannot be obtained by mechanical “Scotch -taping.'” It is also a way to mass produce 2D materials, as mechanical taping only accesses small amounts, insufficient for industrial applications. However, chemical exfoliation comes with the drawback that it commonly introduces many defects into the 2D sheets. In this talk I will show the challenges of using chemical exfoliation for 2D quantum materials synthesis, to then introduce two systems in which the approach was successful. I will show that we can use chemical exfoliation to synthesize large qualities of stable and magnetic monolayers of VOCl. Films of these high-quality sheets are shown to possess similar magnetic properties as the bulk crystals. I will also discuss the synthesis of a stable, aqueous ink of superconducting 1T'-WS2 monolayers. Films printed with the ink are superconducting below 7.3 K and show typical behavior of 2D superconductivity. This ink and its dried, printed version, is stable in ambient conditions. It is ideally suited for applications in flexible and printed electronics. Thus, we were able to establish that chemical exfoliation is of use for quantum materials synthesis.
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    Chemical Exfoliation of Quantum Materials Colloquium website

    Physics Colloquium

    Date:
    04
    Thursday
    April
    2024
    Colloquium
    Time: 11:15-12:30
    Title: The Rolling Stones, All Down the Line
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Tsvi Tlusti
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments will be served at 11:00
    Abstract: Draw an arbitrary open curve on the plane and copy it multiple times to form a t ... Read more Draw an arbitrary open curve on the plane and copy it multiple times to form a translationally invariant infinite trajectory. Then, incline the plane slightly and ask yourself: can one chisel a stone that will roll exactly down this infinite trajectory? We will examine this question in practice and theory. Intriguing links to optics and quantum systems will be discussed. Bringing a tennis ball or a baseball is always recommended. Eckmann et al. Tumbling downhill along a given curve. Am Math Soc Notices - in press. Sobolev et al. Solid-body trajectoids shaped to roll along desired pathways. Nature 2023.
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    Large scale circulation adjustments to aerosol-cloud interactions and its radiative effect

    Date:
    31
    Sunday
    March
    2024
    Lecture / Seminar
    Time: 11:00
    Location: Sussman Family Building for Environmental Sciences
    Lecturer: Guy Dagan
    Organizer: Department of Earth and Planetary Sciences
    Contact: dalia.madhala@weizmann.ac.il
    Abstract: The impact of anthropogenic aerosols on clouds is a leading source of uncertaint ... Read more The impact of anthropogenic aerosols on clouds is a leading source of uncertainty in estimating the effect of human activity on the climate system. The challenge lies in the scale difference between clouds (~1-10 km) and general circulation and climate (~1000 km). To address this, we utilize three different novel sets of simulations that allow to resolve convection while also including a epresentation of large-scale processes. Our findings demonstrate that aerosol-cloud interaction intensifies tropical overturning circulation. Employing a weak temperature gradient approximation, we attribute variations in circulation to clear-sky humidity changes driven by warm rain suppression by aerosols. In two sets of simulations accounting for sub-tropical-tropical coupling, we show that aerosol-driven sub-tropical rain suppression leads to increased advection of cold and moist air from the sub-tropics to the tropics, thus enhancing tropical cloudiness. The increased tropical cloudiness has a strong cooling effect by reflecting more of the incoming solar radiation. The classical “aerosol-cloud lifetime effect” is shown here to have a strong remote effect (sub-tropical aerosols increase cloudiness in the tropics), thus widening the concept of cloud adjustments to aerosol perturbation with important implications for marine cloud brightening.
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    Physics Colloquium

    Date:
    21
    Thursday
    March
    2024
    Colloquium
    Time: 11:15-12:30
    Title: Fractional statistics of anyons in mesoscopic colliders
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Gwendal Fève
    Organizer: Department of Condensed Matter Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments will be served at 11:00
    Abstract: In three-dimensional space, elementary particles are divided between fermions an ... Read more In three-dimensional space, elementary particles are divided between fermions and bosons according to the properties of symmetry of the wave function describing the state of the system when two particles are exchanged. When exchanging two fermions, the wave function acquires a phase, φ=π. On the other hand, in the case of bosons, this phase is zero, φ=0. This difference leads to deeply distinct collective behaviors between fermions, which tend to exclude themselves, and bosons which tend to bunch together. The situation is different in two-dimensional systems which can host exotic quasiparticles, called anyons, which obey intermediate quantum statistics characterized by a phase φ varying between 0 and π [1,2]. For example in the fractional quantum Hall regime, obtained by applying a strong magnetic field perpendicular to a two-dimensional electron gas, elementary excitations carry a fractional charge [3,4] and have been predicted to obey fractional statistics [1,2] with an exchange phase φ=π/m (where m is an odd integer). Using metallic gates deposited on top of the electron gas, beam-splitters of anyon beams can be implemented. I will present how the fractional statistics of anyons can be revealed in collider geometries, where anyon sources are placed at the input of a beam-splitter [5,6]. The partitioning of anyon beams is characterized by the formation of packets of anyons at the splitter output. This results in the observation of strong negative correlations of the electrical current, which value is governed by the anyon fractional exchange phase φ [5,7]. [1] B. I. Halperin, Phys. Rev. Lett. 52, 1583–1586 (1984). [2] D. Arovas, J. R. Schrieffer, F. Wilczek, Phys. Rev. Lett. 53, 722–723 (1984). [3] R. de Picciotto et al., Nature 389, 162–164 (1997). [4] L. Saminadayar, D. C. Glattli, Y. Jin, B. Etienne, Phys. Rev. Lett. 79, 2526–2529 (1997) [5] B. Rosenow, I. P. Levkivskyi, B. I. Halperin, Phys. Rev. Lett. 116, 156802 (2016). [6] H. Bartolomei et al. Science 368, 173-177 (2020). [7] Lee, JY.M., Sim, HS, Nature Communications 13, 6660 (2022).
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    STATISTICAL MECHANICS DAY XV

    Date:
    19
    Tuesday
    March
    2024
    Conference
    Time: 08:00
    Location: Nella and Leon Benoziyo Physics Library
    Organizer: Department of Physics of Complex Systems
    Contact: oren.raz@weizmann.ac.il
    STATISTICAL MECHANICS DAY XV Conference website

    50 Shades of Molecular Modeling in Biomolecular Sciences

    Date:
    05
    Tuesday
    March
    2024
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Nella and Leon Benoziyo Building for Biological Sciences
    Lecturer: Dr. Sofya Lushchekina
    Organizer: Department of Biomolecular Sciences
    Contact: levana.ayvazo@weizmann.ac.il
    Details: Scientific Consultant Israel Silman (invited by Moshe Goldsmith)
    Abstract: The presentation will cover a spectrum of current applications of atomistic mole ... Read more The presentation will cover a spectrum of current applications of atomistic molecular modeling methods in biomolecular problems. Examples of applications of molecular docking, molecular dynamics, combined quantum mechanics/molecular mechanics and dynamics methods, enhanced sampling, and coarse-graining methods, recent machine learning protein structure prediction methods for studying protein structure and dynamics, protein-ligand and protein-protein interactions, and mechanisms of enzymatic reactions will be considered. The advantages and limitations of different computational methods will be discussed.
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    Chemical and Biological Physics Guest seminar

    Date:
    07
    Wednesday
    February
    2024
    Lecture / Seminar
    Time: 15:00-16:00
    Title: The Stark effect in quantum dots: from spectral diffusion to coherent control
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Ron Tenne
    Organizer: Department of Chemical and Biological Physics
    Contact: lucio.frydman@weizmann.ac.il
    Abstract: While colloidal quantum dots (CQDs) are already an important building block in e ... Read more While colloidal quantum dots (CQDs) are already an important building block in electro-optical devices, in the realm of quantum science and technology, they are often considered inferior with respect to emitters such as solid-state defects and epitaxial quantum dots. Despite their single-photon emission [1], demonstrations of quantum coherence and control are largely still lacking. The main obstacle towards these is spectral diffusion – stochastic fluctuations in the energy of photons emitted from an individual CQD even at cryogenic temperatures. In this talk, I will present our recent work providing, for the first time, direct and definitive proof that these fluctuations arise from stochastic electric fields in the particle’s nano environment [2]. However, the high sensitivity of CQDs to electric fields, through the quantum-confined Stark effect, can also be perceived as a feature, rather than a bug. I will present future concepts for coherent control of a single photon’s temporal wavefunction through an electric bias. Relying on tools from the terahertz and femtosecond-laser toolboxes [3,4], spectroscopy and control at fast-to-ultrafast (millisecond-to-femtosecond) timescales, will play a detrimental role in fulfilling the unique potential that CQDs hold in the field of quantum optics,. [1] R. Tenne, U. Rossman, B. Rephael, Y. Israel, A. Krupinski-Ptaszek, R. Lapkiewicz, Y. Silberberg, and D. Oron, Super-Resolution Enhancement by Quantum Image Scanning Microscopy, Nature Photonics 13, 116 (2019). [2] F. Conradt, V. Bezold, V. Wiechert, S. Huber, S. Mecking, A. Leitenstorfer, and R. Tenne, Electric-Field Fluctuations as the Cause of Spectral Instabilities in Colloidal Quantum Dots, Nano Lett. 23, 9753 (2023). [3] P. Henzler et al., Femtosecond Transfer and Manipulation of Persistent Hot-Trion Coherence in a Single CdSe/ZnSe Quantum Dot, Physical Review Letters 126, 067402 (2021). [4] P. Fischer, G. Fitzky, D. Bossini, A. Leitenstorfer, and R. Tenne, Quantitative Analysis of Free-Electron Dynamics in InSb by Terahertz Shockwave Spectroscopy, Physical Review B 106, 205201 (2022).
    Close abstract

    The Clore Center for Biological Physics

    Date:
    21
    Sunday
    January
    2024
    Lecture / Seminar
    Time: 13:15-14:15
    Title: How informative are structures of dna-bound proteins for revealing binding mechanisms inside cells? the case of the Origin of Replication Complex (ORC)
    Location: Nella and Leon Benoziyo Physics Building
    Lecturer: Prof. Naama Barkai,Prof. Naama Barkai
    Organizer: Department of Physics of Complex Systems
    Contact: malka.avraham@weizmann.ac.il
    Details: Lunch at 12:45
    Abstract: The Origin Recognition Complex (ORC) seeds the replication-fork by binding DNA r ... Read more The Origin Recognition Complex (ORC) seeds the replication-fork by binding DNA replication origins, which in budding yeast contain a 17bp DNA motif. High resolution structure of the ORC-DNA complex revealed two base-interacting elements: a disordered basic patch (Orc1-BP4) and an insertion helix (Orc4-IH). To define ORC elements guiding its DNA binding in-vivo, we mapped genomic locations of 38 designed ORC mutants. We revealed that different ORC elements guide binding at different motifs sites, and these correspond only partially to the structure- described interactions. In particular, we show that disordered basic patches are key for ORC-motif binding in-vivo, including one lacking from the structure. Finally i will discuss how those disordered elements, which insert into the minor-groove can still guide specific ORC-DNA recognition.
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    quantum error-correction meets high dimensional expansion, complexity hops on the boat

    Date:
    07
    Sunday
    January
    2024
    -
    10
    Wednesday
    January
    2024
    Conference
    Time: 08:00
    Location: The David Lopatie Conference Centre
    Organizer: The Center for Quantum Science and Technology,Department of Computer Science and Applied Mathematics
    Contact: irit.dinur@weizmann.ac.il
    quantum error-correction meets high dimensional expansion, complexity hops on the boat Conference website

    Chemical and Biological Physics Guest seminar

    Date:
    03
    Wednesday
    January
    2024
    Lecture / Seminar
    Time: 15:00-16:00
    Title: Atomic arrays as programmable quantum processors and sensors
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr Ran Finkelstein
    Organizer: Department of Chemical and Biological Physics
    Contact: lucio.frydman@weizmann.ac.il
    Abstract: Large arrays of trapped neutral atoms have emerged over the past few years as a ... Read more Large arrays of trapped neutral atoms have emerged over the past few years as a promising platform for quantum information processing, combining inherent scalability with high-fidelity control and site-resolved readout. In this talk, I will discuss ongoing work with arrays of Alkaline-earth atoms. These divalent atoms offer unique properties stemming largely from their long-lived metastable states, which form the basis of the optical atomic clock. I will describe the design of a universal quantum processor based on clock qubits and its application in quantum metrology, and I will address the challenge of generating and benchmarking highly entangled states in an analog quantum simulator. First, we realize scalable local control of individual clock qubits, which we utilize to extend the Ramsey interrogation time beyond the coherence time of a single atom [1]. To realize a universal quantum processor, we demonstrate record high-fidelity two-qubit entangling gates mediated by Rydberg interactions, which we combine with dynamical reconfiguration to entangle clock probes in GHZ states and perform Ancilla-based detection [2]. We then use the narrow clock transition to measure and remove thermal excitations of atoms in tweezers (a technique known as erasure conversion) and generate hyperentangled states of motion and spin [3]. In the second part of the talk, I will describe a different approach for generating large scale entangled states in an analog quantum simulator configuration [4], including error mitigation [5] and benchmarking of a 60-atom simulator [6]. Together, these show the great promise and the large variety of experiments accessed with this emerging platform. [1] A. Shaw*, R. Finkelstein*, R. Tsai, P. Scholl, T. Yoon, J. Choi, M. Endres, Multi-ensemble metrology by programming local rotations with atom movements, arxiv:2303.16885, Nature Physics in press (2023). [2] R. Finkelstein, R. Tsai, A. Shaw, X. Sun, M. Endres, A universal quantum processor for entanglement enhanced optical tweezer clocks, in preparation. [3] P. Scholl*, A. Shaw*, R. Finkelstein*, R. Tsai, J. Choi, M. Endres, Erasure cooling, control, and hyper-entanglement of motion in optical tweezers, arXiv:2311.15580 (2023). [4] J. Choi, A. Shaw, I. Madjarov, X. Xie, R. Finkelstein, J. Covey, J. Cotler, D. Mark, H.Y. Huang, A. Kale, H. Pichler, F. Brandão, S. Choi, and M. Endres, Preparing random states and benchmarking with many-body quantum chaos, Nature 617 (2023) [5] P. Scholl, A. Shaw, R. Tsai, R. Finkelstein, J. Choi, M. Endres, Erasure conversion in a high-fidelity Rydberg quantum simulator, Nature 622 (2023). [6] A. Shaw, Z. Chen, J. Choi, D.K. Mark, P. Scholl, R. Finkelstein, A. Elben, S. Choi, M. Endres, Benchmarking highly entangled states on a 60-atom analog quantum simulator, arXiv:2308.07914 (2023).
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    Geometric Functional Analysis and Probability Seminar

    Date:
    21
    Thursday
    December
    2023
    Lecture / Seminar
    Time: 13:30-14:30
    Title: Gaps of Fourier Quasicrystals and Lee-Yang Polynomials
    Location: Jacob Ziskind Building
    Lecturer: Lior Alon
    Organizer: Department of Mathematics
    Contact: hany.kochavi@weizmann.ac.il
    Abstract: The concept of "quasi-periodic" sets, functions, and measures is prevalent in ... Read more The concept of "quasi-periodic" sets, functions, and measures is prevalent in diverse mathematical fields such as Mathematical Physics, Fourier Analysis, and Number Theory. The Poisson summation formula provides a “Fourier characterization” for discrete periodic sets, saying that the Fourier transform of the counting measure of a discrete periodic set is also a counting measure of a discrete periodic set. Fourier Quasicrystals (FQ) generalize this notion of periodicity: a counting measure of a discrete set is called a Fourier quasicrystal (FQ) if its Fourier transform is also a discrete atomic measure, together with some growth condition.      Recently Kurasov and Sarnak provided a method for construction of one-dimensional counting measures which are FQ (motivated by quantum graphs) using the torus zero sets of multivariate Lee-Yang polynomials. In this talk, I will show that the Kurasov-Sarnak construction generates all FQ counting measures in 1D.   A discrete set on the real line is fully described by the gaps between consecutive points. A discrete periodic set has finitely many gaps. We show that a non-periodic FQ has uncountably many gaps, with a well-defined gap distribution. This distribution is given explicitly in terms of an ergodic dynamical system induced from irrational flow on the  torus.   The talk is aimed at a broad audience, no prior knowledge in the field is assumed.   Based on joint works with Alex Cohen and Cynthia Vinzant.
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    Physics Hybrid Colloquium

    Date:
    30
    Thursday
    November
    2023
    Colloquium
    Time: 11:15-12:30
    Title: The Large Array Survey Telescope
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Eran Ofek
    Organizer: Department of Particle Physics and Astrophysics
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments will be served at 11:00
    Abstract: We are building a new ground-based observatory in Neot Smadar, located in the so ... Read more We are building a new ground-based observatory in Neot Smadar, located in the south of the Negev desert. One of the telescopes hosted at this site is the Large Array Survey Telescope (LAST). LAST is a cost-effective survey telescope capable of quickly scanning the sky and studying the dynamic sky, from solar system objects to explosions at cosmological distances. I will describe the Neot Smadar site, the LAST system, and some of the science cases for which LAST was built.
    Close abstract

    TBA

    Date:
    12
    Thursday
    October
    2023
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Julien Fuchs
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments will be served at 11:00
    Abstract: TBA ... Read more TBA
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    How storm develops as the wind blows

    Date:
    05
    Thursday
    October
    2023
    Colloquium
    Time: 11:00-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Gregory Falkovich
    Organizer: Department of Physics of Complex Systems
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments will be served at 11:00
    Abstract: I will describe an attempt to describe turbulence using the methods of quantum f ... Read more I will describe an attempt to describe turbulence using the methods of quantum field theory. We consider waves that interact via four-wave scattering (such as sea waves, plasma waves, spin waves, and many others). By summing the series of the most UV-divergent terms in the perturbation theory, we show that the true dimensionless coupling is different from the naive estimate, and find that the effective interaction either decays or grows explosively with the cascade extent, depending on the sign of the new coupling. The explosive growth possibly signals the appearance of a multi-wave bound state (solitons, shocks, cusps) similar to confinement in quantum chromodynamics.
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    Chemical and Biological and Ben May Seminar

    Date:
    14
    Thursday
    September
    2023
    Lecture / Seminar
    Time: 11:00
    Title: MRSF-TDDFT: Multi-Reference Advantages with The Practicality of Linear Response Theory
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof. Cheol Ho Choi
    Organizer: Ben May Center for Chemical Theory and Computation
    Contact: eli.pollak@weizmann.ac.il
    Abstract: A new quantum theory, MRSF-TDDFT (Mixed-Reference Spin-Flip Time-Dependent Densi ... Read more A new quantum theory, MRSF-TDDFT (Mixed-Reference Spin-Flip Time-Dependent Density Functional Theory) has been developed*, which introduces the multi-reference advantages within the linear response formalism. The density functional theory (DFT) and linear response (LR) time dependent (TD)-DFT are of utmost importance for routine computations. However, the single reference formulation of DFT is suffering from the description of open-shell singlet systems such as diradicals and bond-breaking. LR-TDDFT, on the other hand, finds difficulties in the modeling of conical intersections, doubly excited states, and core-level excitations. Many of these limitations can be overcome by MRSF-TDDFT, providing an alternative yet accurate route for such challenging situations. Now the theory is combined with NAMD, QM/MM, Spin-Orbit Couplings, and Extended Koopman Theorem. Here, we highlight its performances by presenting our recent results by MRSF-TDDFT especially focusing on nonadiabatic molecular dynamics.
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    Physics Colloquium

    Date:
    29
    Thursday
    June
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Quantum Materials: A View from the Lattice
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof Joe Checkelsky
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 Coffee, tea and more...
    Abstract: Connecting theoretical models for exotic quantum states to real materials is a k ... Read more Connecting theoretical models for exotic quantum states to real materials is a key goal in quantum materials science. The structure of the crystalline lattice plays a foundational role in this pursuit in the subfield of quantum material synthesis. We here revisit this long-standing perspective in the context low dimensional emergent electronic phases of matter. In particular, we discuss recent progress in realizing new lattice and superlattice motifs designed to address model topological and correlated electronic phenomena. We comment on the perspective for realizing further 2D model systems in complex material structures and connections to further paradigms for programmable quantum matter.
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    Integrating Crop Models and Satellite Data for Crop Yield Forecasts; and what NASA is looking for in Ukraine?

    Date:
    27
    Tuesday
    June
    2023
    Lecture / Seminar
    Time: 11:30-12:30
    Location: Zoom: https://weizmann.zoom.us/j/91461145626?pwd=QWkzc0xzNndpL3daTDIxdHJPQUlaZz09
    Lecturer: Dr. Yuval Sadeh
    Organizer: Department of Plant and Environmental Sciences
    Contact: david.zeevi@weizmann.ac.il

    Physics colloquium

    Date:
    26
    Monday
    June
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Quantum control of dynamical states with switching times exceeding ten seconds
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof Zaki Leghtas
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 - Coffee, tea and more..
    Abstract: Macroscopic switching times between two stable states are widespread in science ... Read more Macroscopic switching times between two stable states are widespread in science and engineering. Common examples are the reversal of earth's magnetic field, or bit-flips in computer memories. Remarkably, long switching times persist even in systems at wildly reduced scales, such as oscillators containing only a handful of photons. Despite far reaching implications in quantum information science, preparing and measuring quantum superpositions of long-lived dynamical states has remained out of reach. Previous attempts achieved quantum control by introducing ancillary systems that in turn propagated errors limiting the switching times in the millisecond range. In this work, we implement a bistable dynamical system in a nonlinearly dissipative superconducting oscillator with an embedded parametric tool for quantum control and tomography. Through direct Wigner tomography, we observe quantum superpositions of dynamical states with switching times up to twenty seconds. Using quantum Zeno dynamics, we control the phase of these superpositions, and observe coherent oscillations decaying on the scale of hundreds of nanoseconds. This experiment demonstrates the encoding of quantum information in macroscopically stable dynamical states, promising shortcuts in the emergence of quantum technologies. Refs : Leghtas et al. Science 347, 853 (2015). Lescanne et al. Nature Physics 16, 509 (2020). Berdou et al. PRX Quantum preprint arXiv:2204.09128.
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    Physics Colloquium

    Date:
    22
    Thursday
    June
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Seeking the Closest Habitable-Zone Planets
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Suvrath Mahadevan
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Coffee, Tea and more...
    Abstract: The discovery of planets capable of hosting biosignatures, and the characterizat ... Read more The discovery of planets capable of hosting biosignatures, and the characterization of the atmospheres of these planets, is a key and achievable goal in our lifetime. These goals require some of the most demanding precision spectroscopic and photometric measurements. I will discuss the instrumental challenges of detecting such planets with the Doppler radial velocity technique, and the evolution of the design of these instruments as they seek ever-tighter control of environmental parameters, and increased measurement precision. A suite of new technologies like frequency stabilized laser combs, low drift etalons, and deeper understanding of the detectors is enabling a new level of precision in radial velocity measurements - as well as illustrating new challenges. I will then discuss how the stars themselves are the remaining challenge, as magnetically driven processes create ‘stellar activity’ noise that can masquerade as planets and obfuscate their detection, and I highlight a few paths to mitigate this, along with some of the latest scientific results from the HPF and NEID instruments. I will discuss one iteration of a possible future, weaving its way from now through JWST individual and mini-population studies of planet atmospheres, large population studies with missions like ARIEL, the near-future of RV surveys, detection and characterization prospects with large ground-based, and the challenges and opportunities with future imaging and spectroscopic missions like LUVOIR and LIFE. The goal of discovering and characterizing terrestrial mass planets capable of hosting liquid water on their surfaces may now be within reach! But true understanding of the origin and meaning of the biosignatures we detect will likely require transdisciplinary research across multiple fields.
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    Physics Colloquium

    Date:
    15
    Thursday
    June
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Search for quantum applications and taking POCs to production
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Helmut Katzgraber
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 Coffee, tea and more...
    Abstract: The Amazon Quantum Solutions Lab works closely with enterprise customers to iden ... Read more The Amazon Quantum Solutions Lab works closely with enterprise customers to identify use cases where quantum technologies might have impact in the fault-tolerant future, but also to develop creative ways to solve complex business challenges at scale today. In this presentation, I will showcase selected customer use cases and discuss where and when quantum machines can have an impact.
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    Chemical and Biological Physics Guest Seminar

    Date:
    15
    Thursday
    June
    2023
    Lecture / Seminar
    Time: 11:00
    Title: Ratchet based ion pumps
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr Gideon Segev
    Organizer: Department of Chemical and Biological Physics
    Contact: omer.yaffe@weizmann.ac.il
    Abstract: Even though highly selective ion pumps can be found in every living cell membran ... Read more Even though highly selective ion pumps can be found in every living cell membrane, artificial, membrane-based ion selective separation is a longstanding unmet challenge in science and engineering. The development of a membrane-based ion separation technology can drive a dramatic progress in a wide range of applications such as: water treatment, bio-medical devices, extraction of precious metals from sea water, chemical sensors, solar fuels and more. In this seminar I will discuss our theoretical and experimental demonstration of ion pumps based on an electronic flashing ratchet mechanism. Electronic flashing ratchets are devices that utilize modulation in a spatially varying electric field to drive steady state current. Like peristaltic pumps, where the pump mechanism is not in direct contact with the pumped fluid, electronic ratchets induce net current with no direct charge transport between the power source and the pumped charge carriers. Thus, electronic ratchets can be used to pump ions in steady state with no electrochemical reactions between the power source and the pumped ions resulting in an “all electric” ion pump. Ratchet-based ion pumps (RBIPs) were fabricated by coating the two surfaces of nano-porous alumina wafers with gold forming nano-porous capacitor-like devices. The electric field within the nano-pores is modulated by oscillating the capacitors voltage. Thus, when immersed in solution, ions within the pores experience a modulating electric field resulting in ratchet-based ion pumping. The RBIPs performance was studied for various input signals, geometries, and solutions. RBIPs were shown to drive ionic current densities of several μA/cm2 even when opposed by an electrostatic force. A significant ratchet action was observed with input signal amplitudes as low as 0.1V thus demonstrating that RBIPs can drive an ionic current with no associated redox reactions. Simulations show that frequency dependent flux inversions in ratchet systems may pave the way towards ion selective RBIPs.
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    Joint Chemical and Biological Physics and Molecular Chemistry and Materials Science Guest Seminar

    Date:
    13
    Tuesday
    June
    2023
    Lecture / Seminar
    Time: 10:00-11:00
    Title: Tunneling and Zero-Point Energy Effects in Multidimensional Hydrogen Transfer Reactions
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr Yair Litman
    Organizer: Department of Chemical and Biological Physics
    Contact: lucio.frydman@weizmann.ac.il
    Abstract: ydrogen transfer reactions play a prominent role in nature and many technologica ... Read more ydrogen transfer reactions play a prominent role in nature and many technological applications. Despite appearing to be simple reactions, they constitute complex processes where nuclear quantum effects (NQE) such as zero-point energy and nuclear tunneling play a decisive role even at ambient temperature. In this talk, I will show how state-of-the-art methodologies based on the path integral formulation of quantum mechanics in combination with the density functional approximation provide the unique possibility to theoretically address these effects in complex environments. The first part of the talk will focus on the porphycene molecule in the gas phase and adsorbed on metallic surfaces. The porphycene molecule constitutes a paradigmatic example of a molecular switch and has recently received great attention due to its intriguing hydrogen dynamics. I will demonstrate how a correct treatment of NQE, as well as the inclusion of multidimensional anharmonic couplings, are essential to obtain qualitatively correct results regarding the non-trivial temperature dependence of the hydrogen transfer rates and vibrational spectra [1-3]. Finally, I shall also mention some of our recent results for hydrogen diffusion on metals for which non-adiabatic effects, in addition to NQE, play a significant role and can lead to “quantum localization” [4-6]. [1] Y. Litman, J. O. Richardson, T. Kumagai, and M. Rossi, J. Am. Chem. Soc. 141, 2526 (2019) [2] Y. Litman, J. Behler, and M. Rossi, Faraday Discuss. 221, 526 (2020) [3] Y. Litman and M. Rossi, Phys. Rev. Lett. 125, 216001 (2020) [4] Y. Litman, E. S. Pos. C. L. Box, R. Martinazzo, R. J. Maurer, and M. Rossi, J. Chem. Phys. 156, 194106 (2022) [5] Y. Litman, E. S. Pos. C. L. Box, R. Martinazzo, R. J. Maurer, and M. Rossi , J. Chem. Phys. 156, 194107 (2022) [6] O. Bridge, R. Martinazzo, S. C. Althorpe, Y. Litman, in preparation (2023)
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    Probing nanocrystal photophysics with spectator excitons

    Date:
    11
    Sunday
    June
    2023
    Lecture / Seminar
    Time: 10:00-11:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Sanford Ruhman
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Femtosecond pump-probe experiments on nanocrystals are interpreted primarily in ... Read more Femtosecond pump-probe experiments on nanocrystals are interpreted primarily in terms of state filling of the states involved in the intense band edge absorption features, and bi-exciton shifting which changes the resonance energy of the probe pulse due to presence of pump induced excitations. Results have been interpreted to show 1) that “hot” excitons will relax to the lowest available levels in the conduction band in ~1 ps, and 2) that said intense band edge exciton transition will be bleached linearly with excitons until the underlying states are completely filled. In the talk we describe a new approach involving “spectator excitons” to test these accepted views. It consists of comparing pump-probe experiments on pristine samples, with equivalent scans conducted on the same sample after it has been saturated in cold mono-excitons. We show how this method has uncovered previously unrecognized spin blockades in the relaxation of hot multi-exciton states in CdSe NCs, and simply detects stimulated emission signals even in presence of overlapping absorption. We report specific difficulties of applying this approach on perovskite crystals leading to controversial determination that in quantum confined CsPbBr3 bi-exciton interactions are positive (repulsive) and describe recent time resolved emission data which challenges this result.
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    “How atoms jiggle and wiggle in energy materials”

    Date:
    07
    Wednesday
    June
    2023
    Lecture / Seminar
    Time: 10:30-11:30
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. David Egger
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract:   Energy materials are crystalline, solid-state substances with technological ... Read more   Energy materials are crystalline, solid-state substances with technological applications in energy-conversion or storage devices that include solar cells and batteries. In our work, we are particularly interested in scenarios where these systems show unusual structural dynamical effects. These effects trigger many puzzling questions in regard to updated structure-property relations and improved theoretical understandings of these solids. In my talk, I will present our recent findings regarding theoretical treatments of structural dynamics in energy materials and how we may use them to improve our understanding of their finite-temperature properties. The results will focus on halide perovskite as well as nitride semiconductors and solid-state ion conductors, which we typically investigate in tandem with experiment.
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    Ben May Lecutre Series

    Date:
    01
    Thursday
    June
    2023
    Lecture / Seminar
    Time: 14:00-15:00
    Title: Coherence Maps and State-to-State Pathways of Excitation Energy Transfer
    Location: Stone Administration Building
    Lecturer: Prof Nancy Makri
    Organizer: Ben May Center for Chemical Theory and Computation
    Contact: eli.pollak@weizmann.ac.il
    Abstract: The interplay among electronic coherence, vibrational damping, quantum dispersio ... Read more The interplay among electronic coherence, vibrational damping, quantum dispersion, topological effects and thermal fluctuations leads to rich behaviors in the dynamics of excitation energy flow. We use real-time path integral methods developed in our group to perform fully quantum mechanical simulations of excitation energy transfer in large molecular aggregates. The systems are described through a Frenkel exciton Hamiltonian where all vibrational normal modes of each molecular unit and their coupling to the ground and excited electronic states are treated explicitly at any temperature. Simulations have been carried out in J aggregates of perylene bisimide, model dendrimers, and photosynthetic light harvesting complexes. Coherence maps offer powerful visualization tools that reveal the creation and destruction of quantum superpositions and enable a state-to-state pathway analysis of energy flow.
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    Physics Colloquium

    Date:
    01
    Thursday
    June
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Elastic Strain Engineering for Unprecedented Properties
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Ju Li
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: The emergence of “ultra-strength materials” that can withstand significant f ... Read more The emergence of “ultra-strength materials” that can withstand significant fractions of the ideal strength at component scale without any inelastic relaxation harbingers a new field within mechanics of materials. Recently, we have experimentally achieved more than 13% reversible tensile strains in Si that fundamentally redefines what it means to be Si, and ~7% uniform tensile strain in micron-scale single-crystalline diamond bridge arrays, where thousands of transistors and quantum sensors can be integrated in one diamond microbridge. Elastic Strain Engineering (ESE) aims to endow material structures with very large stresses and stress gradients to guide electronic, photonic, and spin excitations and control energy, mass, and information flows. As “smaller is stronger” for most engineering materials at room temperature, a much larger dynamical range of tensile-and-shear deviatoric stresses for small-scale structures can be achieved, as the defect (e.g., dislocation, crack) population dynamics change from defect-propagation to defect-nucleation controlled. Thus, all six stress components can be used to tune the physical and chemical properties of a material like a 7-element alloy. Four pillars of ESE need to be addressed experimentally and computationally: (a) making materials and structures that can withstand deviatoric elastic strain patterns that are exceptionally large and extended in space-time volume, inhomogeneous, dynamically reversible, or combinations thereof, (b) measuring and understanding how functional properties such as photonic and electronic characteristics vary with imposed elastic strain tensor, (c) characterizing and modeling the mechanisms of stress relaxations; the goal is not to use them for forming but to defeat them at service temperatures (usually room temperature and above) and extended timescales, and (d) computational design based on first principles, e.g. predicting ideal strength surface, topological changes in band structures, etc. assisted by machine learning.
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    Solar Panels for Light-to-Chemical Conversion

    Date:
    29
    Monday
    May
    2023
    Colloquium
    Time: 11:00-12:15
    Title: 2023 G.M.J. SCHMIDT MEMORIAL LECTURE
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Erwin Reisner
    Organizer: Faculty of Chemistry
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: Solar panels are well known to produce electricity, but they are also in early-s ... Read more Solar panels are well known to produce electricity, but they are also in early-stage development for the production of sustainable fuels and chemicals. These panels mimic plant leaves in shape and function as demonstrated for overall solar water splitting to produce green H2 by the laboratories of Nocera and Domen.1,2 This presentation will give an overview of our recent progress to construct prototype solar panel devices for the conversion of carbon dioxide and solid waste streams into fuels and higher-value chemicals through molecular surface-engineering of solar panels with suitable catalysts. Specifically, a standalone ‘photoelectrochemical leaf’ based on an integrated lead halide perovskite-BiVO4 tandem light absorber architecture has been built for the solar CO2 reduction to produce syngas.3 Syngas is an energy-rich gas mixture containing CO and H2 and currently produced from fossil fuels. The renewable production of syngas may allow for the synthesis of renewable liquid oxygenates and hydrocarbon fuels. Recent advances in the manufacturing have enabled the reduction of material requirements to fabricate such devices and make the leaves sufficiently light weight to even float on water, thereby enabling application on open water sources.4 The tandem design also allows for the integration of biocatalysts and the selective and bias-free conversion of CO2-to-formate has been demonstrated using enzymes.5 The versatility of the integrated leaf architecture has been demonstrated by replacing the perovskite light absorber by BiOI for solar water and CO2 splitting to demonstrate week-long stability.6 An alternative solar carbon capture and utilisation technology is based on co-deposited semiconductor powders on a conducting substrate.2 Modification of these immobilized powders with a molecular catalyst provides us with a photocatalyst sheet that can cleanly produce formic acid from aqueous CO2.7 CO2-fixing bacteria grown on such a ‘photocatalyst sheet’ enable the production of multicarbon products through clean CO2-to-acetate conversion.8 The deposition of a single semiconductor material on glass gives panels for the sunlight-powered conversion plastic and biomass waste into H2 and organic products, thereby allowing for simultaneous waste remediation and fuel production.9 The concept and prospect behind these integrated systems for solar energy conversion,10 related approaches,11 and their relevance to secure and harness sustainable energy supplies in a fossil-fuel free economy will be discussed.
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    Solar Panels for Light-to-Chemical Conversion Colloquium website

    Ultrafast, Nonlinear and Quantum Optics

    Date:
    29
    Monday
    May
    2023
    -
    31
    Wednesday
    May
    2023
    Conference
    Time: 08:00
    Location: The David Lopatie Conference Centre
    Organizer: Department of Physics of Complex Systems,Crown Photonics Center
    Contact: talia.tzahor@weizmann.ac.il
    Ultrafast, Nonlinear and Quantum Optics Conference website

    Magnetic Resonance Seminar: "Quantum sensing of out-of-equilibrium systems with magnetic resonance”

    Date:
    28
    Sunday
    May
    2023
    Lecture / Seminar
    Time: 16:00-17:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Gonzalo A. Alvarez
    Organizer: The Center for Quantum Science and Technology
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Reliable processing of quantum information is crucial for quantum technologies d ... Read more Reliable processing of quantum information is crucial for quantum technologies development. Characterizing the ubiquitous out-of-equilibrium quantum systems [1-3] is essential for designing optimal control and quantum sensing strategies. However, this task is highly challenging due to the complex high-order correlations and non-stationary nature. In this talk, I will present methods to characterize the decoherence of out-of-equilibrium quantum systems [1,4-6]. Using quantum simulations with Solid-State Nuclear Magnetic Resonance, we quantify "out-of-time order correlations" (OTOCs [2-3]) to define a critical threshold in disturbances to achieve reliable control of large quantum systems [1,4-5]. Furthermore, we develop a framework for quantum sensing the dynamics of out-of-equilibrium systems [6]. The sensor manifests spectral and non-Markovian properties, providing a quantum technology to probe time-correlation properties and mitigate the decoherence effects of non-stationary environments. [1] G. A. Alvarez, D. Suter, R. Kaiser. Science 349, 846 (2015). [2] R.J. Lewis-Swan, A. Safavi-Naini, A.M. Kaufman, A.M. Rey. Nat. Rev. Phys. 1, 627 (2019). [3] B. Swingle. Nat. Phys. 14, 988 (2018). [4] F.D. Dominguez, M.C. Rodriguez, R. Kaiser, D. Suter, G.A. Alvarez. Phys. Rev. A 104, 012402 (2021). [5] F.D. Dominguez, G.A. Alvarez. Phys. Rev. A 104, 062406 (2021). [6] M. Kuffer, A. Zwick, G.A. Alvarez. PRX Quantum 3, 020321 (2022).
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    Ultrafast processes and the challenge of decoherence

    Date:
    22
    Monday
    May
    2023
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Eberhard K. U. Gross
    Organizer: Faculty of Chemistry
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: A prominent goal of present-day condensed-matter physics is the design of electr ... Read more A prominent goal of present-day condensed-matter physics is the design of electronic devices with ever faster switching times. As an example I will present the optically induced spin transfer between magnetic sublattices, the so-called OISTR effect, which allows the switching of magnetic textures on the scale of a femto-second or less. This effect was first predicted with real-time TDDFT and later confirmed in many experiments. To create from this effect a real-world device on has to face the problem of decoherence, i.e. the phenomenon that quantum systems tend to lose their quantumness due to interactions with the environment. For electrons, the principal source of decoherence is the non-adiabatic interaction with nuclear degrees of freedom, i.e. with an “environment” that cannot be removed. In fact, the paradigm of electronic-structure theory where electrons move in the static Coulomb potential of clamped nuclei, while useful in the ground state, is an idealization hardly ever satisfied in dynamical processes. Non-adiabaticity, i.e. effects of the coupled motion of electrons and nuclei beyond the Born-Oppenheimer approximation are found everywhere. In this lecture, the exact factorization will be presented as a universal approach to understand and, ultimately, control non-adiabatic effects, in particular decoherence, from an ab-initio perspective.
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    Ultrafast processes and the challenge of decoherence Colloquium website

    Why Can’t We Classically Describe Quantum Systems?

    Date:
    10
    Wednesday
    May
    2023
    Lecture / Seminar
    Time: 13:00-14:00
    Location: Nella and Leon Benoziyo Physics Library
    Lecturer: Dr. Chinmay Nirkhe
    Organizer: The Center for Quantum Science and Technology
    Contact: rotem.arn@weizmann.ac.il
    Abstract: A central goal of physics is to understand the low-energy solutions of quantum ... Read more A central goal of physics is to understand the low-energy solutions of quantum interactions between particles. This talk will focus on the complexity of describing low-energy solutions; I will show that we can construct quantum systems for which the low-energy solutions are highly complex and unlikely to exhibit succinct classical descriptions. I will discuss the implications these results have for robust entanglement at constant temperature and the quantum PCP conjecture. En route, I will discuss our positive resolution of the No Lowenergy Trivial States (NLTS) conjecture on the existence of robust complex entanglement. Mathematically, for an n-particle system, the low-energy states are the eigenvectors corresponding to small eigenvalues of an exp(n)-sized matrix called the Hamiltonian, which describes the interactions between the particles. Low-energy states can be thought of as approximate solutions to the local Hamiltonian problem with ground-states serving as the exact solutions. In this sense, low-energy states are the quantum generalizations of approximate solutions to satisfiability problems, a central object of study in theoretical computer science. I will discuss the theoretical computer science techniques used to prove circuit lower bounds for all low-energy states. This morally demonstrates the existence of Hamiltonian systems whose entire low-energy subspace is robustly entangled.
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    Physics Colloquium

    Date:
    10
    Wednesday
    May
    2023
    Colloquium
    Time: 11:15-12:00
    Title: GW astrophysics with LIGO/VIRGO data
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Matias Zaldarriaga
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: refreshments at 11:00
    Abstract: I will describe some of our recent work re-analyzing the gravitational wave data ... Read more I will describe some of our recent work re-analyzing the gravitational wave data made public by the LIGO collaboration. More broadly I will discuss some of the outstanding questions related to binary black hole mergers and what the data might be saying about how the GW sources formed. I will comment on some fruitful directions for further improvements.
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    Physics Colloquium

    Date:
    09
    Tuesday
    May
    2023
    Colloquium
    Time: 11:00-12:30
    Title: Intense Laser-Material Interactions: Stars, Exoplanets, and Unique States of Matter in the Laboratory
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Christopher Deeney
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 11:00
    Abstract: Since 1970, the University of Rochester and other laboratories around the world ... Read more Since 1970, the University of Rochester and other laboratories around the world have built more energetic and more powerful lasers. These technology advances have enabled new science regimes. Fifty years later, fusion ignition has been achieved in the laboratory , where more energy than the laser energy was released ; an amazing demonstration of precision science under extreme conditions.Astrophysics is now a laboratory science-new equations of state, constitutive properties and structures are measured at conditions equivalent to giant gas planets and super earths. Ultrashort pulse lasers, a LLE invention acknowledged in the 2018 Nobel Prize for Physics, is enabling ultrahigh field physics and new generations of particle accelerators and light sources. Recent progress on ignition, high-energy-density science and short-pulse laser physics will be summarized. The pursuit of direct-drive fusion and the path to 25 Petawatt lasers will be discussed.
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    Foundations of Computer Science Seminar

    Date:
    08
    Monday
    May
    2023
    Lecture / Seminar
    Time: 11:15-12:45
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is long-standing open question in quantum complexity theory whether the defin ... Read more It is long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (QMA) or if classical witnesses suffice (QCMA). We make progress on this question by constructing a randomized classical oracle separating the respective computational complexity classes. Previous separations [Aaronson-Kuperberg (CCC'07), Fefferman-Kimmel (MFCS'18)] required a quantum unitary oracle. The separating problem is deciding whether a distribution supported on regular un-directed graphs either consists of multiple connected components (yes instance) or consists of one expanding connected component (no instances) where the graph is given in an adjacency-list format by the oracle. Therefore, the oracle is a distribution over n-bit boolean functions.
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    Approaching non-equilibrium: from machine learning to non-adiabatic dynamics

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Dr. Sergei Tretiak
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Machine learning (ML) became a premier tool for modeling chemical processes and ... Read more Machine learning (ML) became a premier tool for modeling chemical processes and materials properties. For instance, ML interatomic potentials have become an efficient alternative to computationally expensive quantum chemistry simulations. In the case of reactive chemistry designing high-quality training data sets is crucial to overall model accuracy. To address this challenge, we develop a general reactive ML interatomic potential through unbiased active learning with an atomic configuration sampler inspired by nanoreactor molecular dynamics. The resulting model is then applied to study five distinct condensed-phase reactive chemistry systems: carbon solid-phase nucleation, graphene ring formation from acetylene, biofuel additives, combustion of methane and the spontaneous formation of glycine from early-earth small molecules. In all cases, the results closely match experiment and/or previous studies using traditional model chemistry methods. Altogether, explosive growth of user-friendly ML frameworks, designed for chemistry, demonstrates that the field is evolving towards physics-based models augmented by data science. I will also overview some applications of Non-adiabatic EXcited-state Molecular Dynamics (NEXMD) framework developed at several institutions. The NEXMD code is able to simulate tens of picoseconds photoinduced dynamics in large molecular systems. As an application, I will exemplify ultrafast coherent excitonic dynamics guided by intermolecular conical intersections. Here X-ray Raman signals are able to sensitively monitor the coherence evolution. The observed coherences have vibronic nature that survives multiple conical intersection passages for several hundred femtoseconds at room temperature. These spectroscopic signals are possible to measure at XFEL facilities and our modeling results allow us to understand and potentially manipulate excited state dynamics and energy transfer pathways toward optoelectronic applications. References: 1. N. Fedik, R. Zubatyuk, N. Lubbers, J. S. Smith, B. Nebgen, R. Messerly, Y. W. Li, M. Kulichenko, A. I. Boldyrev, K. Barros, O. Isayev, and S. Tretiak “Extending machine learning beyond interatomic potentials for predicting molecular properties” Nature Rev. Chem. 6, 653 (2022). 2. G. Zhou, N. Lubbers, K. Barros, S. Tretiak, B. Nebgen, “Deep Learning of Dynamically Responsive Chemical Hamiltonians with Semi-Empirical Quantum Mechanics,” Proc. Nat. Acad. Sci. USA, 119 e2120333119 (2022) 3. S. Zhang, M. Z. Makos, R. B. Jadrich, E. Kraka, B. T. Nebgen, S. Tretiak, O. Isayev, N. Lubbers, R. A. Messerly, and J. S. Smith “Exploring the frontiers of chemistry with a general reactive machine learning potential,” (2023) https://chemrxiv.org/engage/chemrxiv/article-details/6362d132ca86b84c77ce166c 4. A. De Sio, E. Sommer, X. T. Nguyen, L. Gross, D. Popović, B. Nebgen, S. Fernandez-Alberti, S. Pittalis, C. A. Rozzi, E. Molinari, E. Mena-Osteritz, P. Bäuerle, T. Frauenheim, S. Tretiak, C. Lienau, “Intermolecular conical intersections in molecular aggregates” Nature Nanotech. 16, 63 – 68 (2021). 5. V. M. Freixas, D. Keefer, S. Tretiak, S. Fernandez-Alberti, and S. Mukamel, “Ultrafast coherent photoexcited dynamics in a trimeric dendrimer probed by X-ray stimulated-Raman signals,” Chem. Sci., 13, 6373 – 6384 (2022).
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    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-13:00
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-13:00
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-13:00
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-12:45
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-12:30
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-12:30
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
    Close abstract

    Foundations of Computer Science Seminar

    Date:
    24
    Monday
    April
    2023
    Lecture / Seminar
    Time: 11:15-12:45
    Title: A distribution testing oracle separation between QMA and QCMA
    Location: Jacob Ziskind Building
    Lecturer: Chinmay Nirkhe
    Organizer: Department of Computer Science and Applied Mathematics
    Contact: karina.avadia@weizmann.ac.il
    Abstract: It is a long-standing open question in quantum complexity theory whether the def ... Read more It is a long-standing open question in quantum complexity theory whether the definition of non-deterministic quantum computation requires quantum witnesses (
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    Quantum computing with trapped ions

    Date:
    17
    Monday
    April
    2023
    Lecture / Seminar
    Time: 13:15
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Ferdinand Schmidt-Kaler (QUANTUM, Johannes Gutenberg Universität Mainz)
    Organizer: The Center for Quantum Science and Technology
    Contact: eti.shalem@weizmann.ac.il
    Details: Falafel at 12:45
    Abstract: Quantum technologies allow for fully novel schemes of hybrid computing. We empl ... Read more Quantum technologies allow for fully novel schemes of hybrid computing. We employ modern segmented ion traps. I will sketch architectures, the required trap technologies and fabrication methods, control electronics for quantum register reconfigurations, and recent improvements of qubit coherence and gate performance. Currently gate fidelities of 99.995% (single bit) and 99.8% (two bit) are reached. We are implementing a reconfigurable qubit register and have realized multi-qubit entanglement [1] and fault-tolerant syndrome readout [2] in view for topological quantum error correction [3] and realize user access to quantum computing [4]. The setup allows for mid-circuit measurements and real-time control of the algorithm. We are currently investigating various used cases, including variational quantum eigensolver approaches for chemistry or high energy relevant models, and measurement-based quantum computing. The fully equipped in house clean room facilities for selective laser etching of glass enables us to design and fabricate complex ion trap devices, in order to scale up the number of fully connected qubits. Also, we aim for improving on the speed of entanglement generation. The unique and exotic properties of ions in Rydberg states [5] are explored experimentally, staring with spectroscopy [6] of nS and nD states where states with principal quantum number n=65 are observed. The high polarizability [7] of such Rydberg ions should enable sub-μs gate times [8]. [1] Kaufmann er al, Phys. Rev. Lett. 119, 150503 (2017) [2] Hilder, et al., Phys. Rev. X.12.011032 (2022) [3] Bermudez, et al, Phys. Rev. X 7, 041061 (2017) [4] https://iquan.physik.uni-mainz.de/ [5] A. Mokhberi, M. Hennrich, F. Schmidt-Kaler, Trapped Rydberg ions: a new platform for quantum information processing, Advances In Atomic, Molecular, and Optical Physics, Academic Press, Ch. 4, 69 (2020), arXiv:2003.08891 [6] Andrijauskas et al, Phys. Rev. Lett. 127, 203001 (2021) [7] Niederlander et al, NJP 25 033020 (2023) [8] Vogel et al, Phys. Rev. Lett. 123, 153603 (2019)
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    Polymorphous networks of intrinsic local motifs in crystals

    Date:
    17
    Monday
    April
    2023
    Colloquium
    Time: 11:00-12:15
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Alex Zunger
    Organizer: Faculty of Chemistry
    Contact: sarah.amzallag@weizmann.ac.il
    Abstract: Predicting properties of crystals and molecules via quantum theory of matter gen ... Read more Predicting properties of crystals and molecules via quantum theory of matter generally requires knowing (A) the nature of electronic interactions in the system, and (B) where atoms and various moments are (“structure”). Some of the historical failures to predict basic effects in ‘Quantum Materials’ were often tracked back to the need to improve our understanding of (A), such as accounting for ‘strong electron correlation’. Examples include Mott insulators; mass enhancement in superconductors; metal-insulator transitions in oxides, or even the quantitative underestimation of predicted band gaps of cubic Halide Perovskites. This talk explores a different resolution of the aforementioned conflicts with experiment in terms of hidden structure (B) above. This include configurations of magnetic moments or electric dipole moments, not only in the ordered ground states, but also in paramagnetic and paraelectric phases, and in nonmagnetic cubic phases of halide perovskites, all considered previously to be ‘featureless phases. Importantly, such ‘Quantum Texture’ can be predicted theoretically by minimization of the constrained internal energy, even before temperature sets in. It thus represents intrinsic tendencies to lower energy by breaking symmetry. Using such polymorphous networks in band theory explains Mott physics without correlation as well as Halide Perovskites before dynamics. This highlights the importance of experimental observation of distributions of local symmetries, distinct from the global average crystallographic symmetries.
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    Polymorphous networks of intrinsic local motifs in crystals Colloquium website

    Chemical and Biological Physics Guest Seminar

    Date:
    02
    Sunday
    April
    2023
    Lecture / Seminar
    Time: 14:00
    Title: Ab initio approaches to nonequilibrium dynamics and molecular quantum systems
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof Prineha Narang
    Organizer: Department of Chemical and Biological Physics
    Contact: Gilad.haran@weizmann.ac.il
    Abstract: In this talk, I will present theoretical and computational chemistry approaches ... Read more In this talk, I will present theoretical and computational chemistry approaches to describe excited-states in quantum matter, and predicting emergent states created by external drives. Understanding the role of such light-matter interactions in the regime of correlated electronic systems is of paramount importance to fields of study across chemical and condensed matter physics, and ultrafast dynamics1. The simultaneous contribution of processes that occur on many time and length-scales have remained elusive for state-of-the-art calculations and model Hamiltonian approaches alike, necessitating the development of new methods in computational chemistry. I will discuss our work at the intersection of ab initio cavity quantum-electrodynamics and electronic structure methods to treat electrons, photons and phonons on the same quantized footing, accessing new observables in strong light-matter coupling. Current approximations in the field almost exclusively focus on electronic excitations, neglecting electron-photon effects, for example, thereby limiting the applicability of conventional methods in the study of polaritonic systems, which requires understanding the coupled dynamics of electronic spins, nuclei, phonons and photons. With our approach we can access correlated electron-photon and photon-phonon dynamics2–7, essential to our latest work on driving quantum materials far out-of-equilibrium to control the coupled electronic and vibrational degrees-of-freedom 8–19. In the second part of my talk, I will demonstrate how the same approach can be generalized in the context of control of molecular quantum matter and quantum transduction. As a first example, I will discuss a cavity-mediated approach to break the inversion symmetry allowing for highly tunable even-order harmonic generation (e.g. second- and fourth-harmonic generation) naturally forbidden in such systems. This relies on a quantized treatment of the coupled light-matter system, similar to the driven case, where the molecular matter is confined within an electromagnetic environment and the incident (pump) field is treated as a quantized field in a coherent state. When the light-molecule system is strongly coupled, it leads to two important features: (i) a controllable strong-coupling-induced symmetry breaking, and (ii) a tunable and highly efficient nonlinear conversion efficiency of the harmonic generation processes 20–22. Both of these have implications for molecular quantum architectures. Being able to control molecules at a quantum level gives us access to degrees of freedom such as the vibrational or rotational degrees to the internal state structure. Finally, I will give an outlook on connecting ideas in cavity control of molecules with quantum information science.
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    Chemical and Biological Physics Guest Seminar

    Date:
    23
    Thursday
    March
    2023
    Lecture / Seminar
    Time: 10:00-11:00
    Title: Building and testing semiclassical models for molecular plasmonics
    Location: Perlman Chemical Sciences Building
    Lecturer: Prof Maxim Sukharev
    Organizer: Department of Chemical and Biological Physics
    Contact: Gilad.haran@weizmann.ac.il
    Abstract: Molecular plasmonics has been a hot topic for the past several years. At the hea ... Read more Molecular plasmonics has been a hot topic for the past several years. At the heart of the primary interest in plasmonics is the strong electromagnetic field localization at resonant frequencies corresponding to surface plasmon-polariton modes. Thanks to riveting advancements in nanofabrication technologies, we have achieved nearly 1 nm spatial resolution (and in some cases even below that!) and are able to fabricate a wide variety of nanosystems ranging from nanoparticles of various shapes to metasurfaces comprised of periodic arrays of nanoparticles and/or nanoholes of any imaginable geometry. Such systems have recently emerged as new platforms for strong light-matter interactions. Combined with molecular ensembles, these constructs exhibit a remarkable set of optical phenomena ranging from the exciton-plasmon strong coupling to the second harmonic generation altered by molecular resonances. In this talk I will discuss both linear and nonlinear optical properties of plasmonic materials coupled to quantum emitters of various complexity. I will also introduce a newly developed computational approach that can be used to efficiently simulate a large number of complex molecules driven by electromagnetic radiation crafted at plasmonic interfaces.
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    The platypus of the quantum channel zoo

    Date:
    13
    Monday
    March
    2023
    Lecture / Seminar
    Time: 14:00-15:00
    Location: Nella and Leon Benoziyo Physics Building
    Lecturer: Prof. Felix Leditzky
    Organizer: The Center for Quantum Science and Technology
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Understanding quantum channels and the strange behavior of their capacities is a ... Read more Understanding quantum channels and the strange behavior of their capacities is a key driver of quantum information theory. Despite having rigorous coding theorems, quantum capacities are poorly understood due to super-additivity effects. We will talk about a remarkably simple, low-dimensional, single-parameter family of quantum channels with exotic quantum information-theoretic features. As the simplest example from this family, we focus on a qutrit-to-qutrit channel that is intuitively obtained by hybridizing together a simple degradable channel and a completely useless qubit channel. Such hybridizing makes this channel's capacities behave in a variety of interesting ways. For instance, the private and classical capacity of this channel coincide and can be explicitly calculated, even though the channel does not belong to any class for which the underlying information quantities are known to be additive. Moreover, the quantum capacity of the channel can be computed explicitly, given a clear and compelling conjecture is true. This "spin alignment conjecture," which may be of independent interest, is proved in certain special cases and additional numerical evidence for its validity is provided. We further show that this qutrit channel demonstrates superadditivity when transmitting quantum information jointly with a variety of assisting channels, in a manner unknown before. A higher-dimensional variant of this qutrit channel displays super-additivity of quantum capacity together with an erasure channel. Subject to the spin-alignment conjecture, our results on super-additivity of quantum capacity extend to lower-dimensional channels as well as larger parameter ranges. In particular, super-additivity occurs between two weakly additive channels each with large capacity on their own, in stark contrast to previous results. Remarkably, a single, novel transmission strategy achieves super-additivity in all examples. Our results show that super-additivity is much more prevalent than previously thought. It can occur across a wide variety of channels, even when both participating channels have large quantum capacity. This is joint work with Debbie Leung, Vikesh Siddhu, Graeme Smith, and John Smolin, and based on the papers https://arxiv.org/abs/2202.08380 and https://arxiv.org/abs/2202.08377.
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    Tensor networks, fundamental theorems, and complexity

    Date:
    06
    Monday
    March
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Nella and Leon Benoziyo Physics Building
    Lecturer: Prof. Michael Walter
    Organizer: The Center for Quantum Science and Technology
    Contact: eti.shalem@weizmann.ac.il
    Abstract: Tensor networks describe high-dimensional tensors succinctly, in terms of a netw ... Read more Tensor networks describe high-dimensional tensors succinctly, in terms of a network or graph of local data. Many interesting tensors arise in this way -- from many-body quantum states in physics to the matrix multiplication tensors in algebraic complexity. While widely successful, the structure of tensor networks is still only partially understood. In this talk, I will give a gentle introduction to tensor networks and explain some recent advances in their theory. In particular, we will discuss the significance of the so-called “fundamental theorem”, which is at the heart of much of the success of tensor networks, and explain how to generalize it to higher dimensions. Before our work, "no go" results suggested that such a generalization might not exist!! Along the way, we will see how to turn an undecidable problem into one that admits an algorithmic solution. To achieve this we draw on recent progress in theoretical computer science and geometric invariant theory.
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    Strong light-exciton interactions in 2D semiconductors

    Date:
    22
    Wednesday
    February
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Prof. Itai Epstein
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: The remarkable properties of excitons in transition-metal-dichalcogenides (TMDs) ... Read more The remarkable properties of excitons in transition-metal-dichalcogenides (TMDs), together with the ability to readily control their charge carriers, have attracted a significant amount of interest in recent years. Despite the atomic dimensions of the hosting 2D semiconductors, TMD excitons exhibit strong interaction with light, both in absorption and photoemission processes, and practically dominate the optical response of these 2D materials. In this talk, I will introduce several approaches for achieving extremely strong light-exciton interactions. First, by optical and electrical manipulation of TMD excitons inside a van der Waals heterostructure cavity [1], second, via the formation of highly-confined, in-plane exciton polaritons [2], and third, through the realization of valley-polarized hyperbolic exciton polaritons [3]. These enhanced light–exciton interactions may provide a platform for studying excitonic phase-transitions, quantum nonlinearities and the enablement of new possibilities for 2D semiconductor-based optoelectronic devices. [1] I. Epstein et al, "Near-unity Light Absorption in a Monolayer WS2 Van der Waals Heterostructure Cavity", Nano letters 20 (5), 3545-3552 (2020). [2] I. Epstein et al, "Highly Confined In-plane Propagating Exciton-Polaritons on Monolayer Semiconductors", 2D Materials 7, 035031 (2020). [3] T. Eini, T. Asherov, Y. Mazor, and I. Epstein, "Valley-polarized Hyperbolic Exciton Polaritons in Multilayer 2D Semiconductors at Visible Frequencies", Phys. Rev. B 106, L201405 (2022).
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    Physics Colloquium

    Date:
    19
    Sunday
    February
    2023
    Colloquium
    Time: 11:15-12:30
    Title: New Avenues in Quantum Computing: Beyond Quantum Circuits with Trapped-Ion Qubits
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Dr. Or Katz
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 - Coffee, tea and more
    Abstract: Trapped ions are a leading quantum technology for quantum computation and simula ... Read more Trapped ions are a leading quantum technology for quantum computation and simulation, with the capability to solve computationally hard problems and deepen our understanding of complex quantum systems. The quantum circuit model is the central paradigm for quantum computation, enabling the realization of various quantum algorithms by application of multiple one- and two-qubit entangling operations. However, the typical number of entangling operations required by this model increases exponentially with the number of qubits, making it difficult to apply to many problems. In my presentation, I will discuss new methods for realizing quantum gates and simulations that go beyond the quantum circuit model. I will first describe a single-step protocol for generating native, -body interactions between trapped-ion spins, using spin-dependent squeezing. Next, I will present a preparation of novel phases of matter using simultaneous and reconfigurable spin-spin interactions. Lastly, I will explore new avenues to harness the long-lived phonon modes in trapped-ion crystals for simulating complex bosonic and spin-boson models that are difficult to solve using classical methods. The presented techniques could push the performance of trapped-ion systems to solve problems that are currently beyond their reach.
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    Physics Colloquium

    Date:
    02
    Thursday
    February
    2023
    Colloquium
    Time: 11:15-12:30
    Title: Quantum materials by design
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Cory Dean
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 11:00 - coffee, tea and more...
    Abstract: The electronic properties of a material are dictated by both the composition and ... Read more The electronic properties of a material are dictated by both the composition and arrangement of its atomic lattice. Combining elemental atoms selected from the periodic table in principle provides for infinite variety of materials to be realized. However, thermodynamic constraints limit which atoms may bond into which symmetry classes; materials may or may not be air sensitive; synthesis conditions may be impractical; impurities and defects may substantially obscure intrinsic electronic properties; and the resulting electron behaviour may not be predictive owing to phenomena such as strong electron interactions, spontaneous magnetic ordering, fermi-surface reconstruction or other effects not captured by single-particle band-structure calculations. In this talk, I will explore new approaches to synthesizing quantum materials by augmenting the atomic lattice structure in 2D materials with a superimposed superlattice potential. Artificially engineering lattice potentials provide opportunities to synthesize materials beyond the periodic table, with the ultimate promise to be able to realize and manipulate arbitrary electronic states, by design. Opportunities and challenges, in this exciting new field will be reviewed, and the prospects for quantum simulation in a solid-state platform will be discussed.
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    M.Sc thesis defense: “Fermi-polaron description of excitonic scattering processes in layered systems from first principles”

    Date:
    01
    Wednesday
    February
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Perlman Chemical Sciences Building
    Lecturer: Guy Voscoboynik
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: Layered materials exhibit unique charge and energy transfer characteristics, mak ... Read more Layered materials exhibit unique charge and energy transfer characteristics, making them promising candidates for emerging photophysical and photochemical applications, and particularly in energy conversion and quantum information science. In two-dimensional systems, spatial confinement in a certain dimension causes reduced dielectric screening and enhanced Coulomb interaction compared to bulk materials. Upon light excitation, the relaxation processes of the charge and energy carriers, as well as their rearrangement in the lateral plane, allow for unique and structure-specific interaction dynamics of the electrons and holes in these systems and of their bound states - neutral and charged excitons. In particular, these dimensionality effects induce strong exciton-electron and exciton-hole interactions in doped or gated systems, where optical excitations coexist alongside electronic excitations. These interactions dominate the exciton decay and diffusion and introduce bound three-particle states in such systems. A many-particle theoretical picture of the formation and propagation of these states is crucial for proper tracking and understanding of the interaction pathways, crystal momentum effects, the involved particle-particle coupling and their relation to the underlying structure, dimensionality, and symmetry.
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    "Molecules in a Quantum-Optical Flask"

    Date:
    25
    Wednesday
    January
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Gerhard M.J. Schmidt Lecture Hall
    Lecturer: Dr. Tal Schwartz
    Organizer: Department of Molecular Chemistry and Materials Science
    Contact: ana.naamat@weizmann.ac.il
    Abstract: "Molecules in a Quantum-Optical Flask" When confined to small dimensions, the ... Read more "Molecules in a Quantum-Optical Flask" When confined to small dimensions, the interaction between light and matter can be enhanced up to the point where it overcomes all the incoherent, dissipative processes. In this "strong coupling" regime the photons and the material start to behave as a single entity, having its own quantum states and energy levels. In this talk I will discuss how such cavity-QED effects can be used in order to control material properties and molecular processes. This includes, for example, modifying photochemical reactions [1], enhancing excitonic transport up to ballistic motion close to the light-speed [2-3] and potentially tailoring the mesoscopic properties of organic crystals, by hybridizing intermolecular vibrations with electromagnetic THz fields [4-5]. 1. J. A. Hutchison, T. Schwartz, C. Genet, E. Devaux, and T. W. Ebbesen, "Modifying Chemical Landscapes by Coupling to Vacuum Fields," Angew. Chemie Int. Ed. 51, 1592 (2012). 2. G. G. Rozenman, K. Akulov, A. Golombek, and T. Schwartz, "Long-Range Transport of Organic Exciton-Polaritons Revealed by Ultrafast Microscopy," ACS Photonics 5, 105 (2018). 3. M. Balasubrahmaniyam, A. Simkovich, A. Golombek, G. Ankonina, and T. Schwartz, "Unveiling the mixed nature of polaritonic transport: From enhanced diffusion to ballistic motion approaching the speed of light," arXiv:2205.06683 (2022). 4. R. Damari, O. Weinberg, D. Krotkov, N. Demina, K. Akulov, A. Golombek, T. Schwartz, and S. Fleischer, "Strong coupling of collective intermolecular vibrations in organic materials at terahertz frequencies," Nat. Commun. 10, 3248 (2019). 5. M. Kaeek, R. Damari, M. Roth, S. Fleischer, and T. Schwartz, "Strong Coupling in a Self-Coupled Terahertz Photonic Crystal," ACS Photonics 8, 1881 (2021).
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    Magnetism and spin squeezing with arrays of Rydberg atoms

    Date:
    22
    Sunday
    January
    2023
    Lecture / Seminar
    Time: 11:00-13:00
    Title: Magnetism and spin squeezing with arrays of Rydberg atoms
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Antoine Browaeys
    Organizer: The Center for Quantum Science and Technology
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 10:30
    Abstract: This talk will present our recent work on the use of arrays of Rydberg atoms to ... Read more This talk will present our recent work on the use of arrays of Rydberg atoms to study quantum magnetism and to generate entangled states useful for quantum metrology. We rely on laser-cooled ensembles of up to hundred individual atoms trapped in microscopic optical tweezer arrays. By exciting the atoms into Rydberg states, we make them interact by the resonant dipole interaction. The system thus implements the XY spin ½ model, which exhibits various magnetic orders depending on the ferromagnetic or antiferromagnetic nature of the interaction. In particular, we adiabatically prepare long-range ferromagnetic order. When the system is placed out of equilibrium, the interactions generate spin squeezing. We characterize the degree of squeezing and observe that it scales with the number of atoms.
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    Collective light scattering in cold atomic ensembles: super-radiance & driven Dicke model

    Date:
    19
    Thursday
    January
    2023
    Lecture / Seminar
    Time: 16:00-18:00
    Title: Collective light scattering in cold atomic ensembles: super-radiance & driven Dicke model
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Antoine Browaeys
    Organizer: The Center for Quantum Science and Technology
    Contact: eti.shalem@weizmann.ac.il
    Details: Refreshments at 15:30
    Abstract: This talk will present our recent work on the observation of super-radiance in a ... Read more This talk will present our recent work on the observation of super-radiance in a cloud of cold atoms and the implementation of the driven Dicke model in free space. We start from an elongated cloud of laser cooled atoms that we excite either perpendicularly or along its main axis. This situation bears some similarities with cavity quantum electrodynamics: here the cavity mode is replaced by the diffraction mode of the elongated cloud. We observe superradiant pulses of light after population inversion. When exciting the cloud along the main axis, we observe the Dicke super-radiant phase transition predicted 40 years ago and never observed in free space. We also measure the statistics of the emitted light and find that it has the properties predicted for a super-radiant laser.
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    Special Physics Colloquium

    Date:
    10
    Tuesday
    January
    2023
    Colloquium
    Time: 16:15-18:00
    Title: Quantum Simulation: from many to few body problems.
    Location: Edna and K.B. Weissman Building of Physical Sciences
    Lecturer: Prof. Ignacio Cirac
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il
    Details: 15:45- Coffee, tea and Refreshments
    Abstract: Many-body quantum systems are very difficult to simulate with classical computer ... Read more Many-body quantum systems are very difficult to simulate with classical computers, as the computational resources (time and memory) usually grow exponentially with the size of the system. However, quantum computers and analog quantum simulators can perform that task much more efficiently. In this talk, I will first review some of the quantum algorithms that have been proposed to simulate dynamics, prepare ground states, or compute physical properties at finite temperatures. I will then focus on analog quantum simulation with cold atoms in optical lattices and describe methods for tackling physics and chemistry problems with such a system.
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    Quantum metrology for various applications and platforms

    Date:
    09
    Monday
    January
    2023
    Lecture / Seminar
    Time: 14:30-15:30
    Location: Maurice and Gabriela Goldschleger Center For Nanophysics
    Lecturer: Dr. Tuvia Gefen (Caltech)
    Organizer: The Center for Quantum Science and Technology
    Contact: rotem.arn@weizmann.ac.il
    Abstract: The field of quantum metrology seeks to develop quantum protocols to enhance the ... Read more The field of quantum metrology seeks to develop quantum protocols to enhance the precision of measurements with applications ranging from NMR and gravimeters to calibration of quantum devices. The general tools and bounds of quantum metrology assume perfect detection. However, the detection in most quantum experimental platforms is noisy and imperfect. We fill this gap and develop a theory that takes into account general measurements . We generalize the precision bounds to account for arbitrary detection channels. We find the general form of the precision bounds and of the optimal control for pure states. We then consider quantum states in a multi-partite system and study the impact of detection noise on quantum enhancement in sensitivity. Interestingly, the achievable sensitivity depends crucially on the allowed control operations. For local optimal control, the detection noise severely degrades the sensitivity and limits any quantum enhancement to a constant factor. On the other hand, with optimal global control the detection noise can be completely removed, and the noiseless sensitivity bounds can be retrieved for a generic class of quantum states (including all pure states and symmetric states).
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    Example 1 for internal event node

    Date:
    08
    Monday
    May
    2017
    -
    10
    Wednesday
    May
    2017
    Retreat
    Time: 10:00 - 12:30
    Location: David Lopatie Conference Centre ...
    Organizer: Department of ...
    Contact: weizmann@weizmann.ac.il

    Example 2 for internal event node

    Date:
    08
    Monday
    May
    2017
    -
    10
    Wednesday
    May
    2017
    Retreat
    Time: 10:00 - 12:30
    Location: David Lopatie Conference Centre ...
    Organizer: Department of ...
    Contact: weizmann@weizmann.ac.il