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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
    Contact: irit.dinur@weizmann.ac.il
    quantum error-correction meets high dimensional expansion, complexity hops on the boat Conference website

    Quantum computing over the rainbow: from scalable qumodes to scalable fault-tolerant qubits -- Prof. Olivier Pfister (University of Virginia)

    Date:
    05
    Monday
    June
    2023
    Lecture / Seminar
    Time: 11:00-12:00
    Location: Drory Auditorium
    Organizer: AMOS Seminar

    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).
    Close abstract

    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.
    Close abstract

    The Quantum Age: From Bell Pairs to Quantum Computers -- Prof. Vladan Vuletić (MIT)

    Date:
    01
    Monday
    May
    2023
    Colloquium
    Time: 11:15-12:15
    Location: Drory Auditorium
    Organizer: Physics Faculty

    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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    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.
    Close abstract

    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.
    Close abstract

    New Avenues in Quantum Computing: Beyond Quantum Circuits with Trapped-Ion Qubits -- Dr. Or Katz (Yale University)

    Date:
    19
    Sunday
    February
    2023
    Colloquium
    Time: 11:15-12:30
    Location: Edna and K.B. Weissman Building of Physical Sciences Auditorium
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il

    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.
    Close abstract

    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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    Quantum Simulation: from many to few body problems -- Prof. Ignacio Cirac (Max Plank Institute for Quantum Optics, Garching)

    Date:
    10
    Tuesday
    January
    2023
    Colloquium
    Time: 16:15-18:00
    Location: Edna and K.B. Weissman Building of Physical Sciences, Weissman Auditorium
    Organizer: Faculty of Physics
    Contact: eti.shalem@weizmann.ac.il

    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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    Quantum Information Processing with Light: from Single Photons to Continuous Variables -- Dr. Lior Cohen (Colorado University Boulder)

    Date:
    08
    Sunday
    January
    2023
    Lecture / Seminar
    Time: 11:15-12:00
    Location: Drory Auditorium
    Organizer: AMOS Seminar

    Optically-active solid-state spins in photonic platforms for quantum science and technology -- Dr. Demitry Farfunik (University of Maryland)

    Date:
    04
    Wednesday
    January
    2023
    Lecture / Seminar
    Time: 15:00-16:00
    Location: Schmidt Auditorium
    Organizer: Chemical and Biological Physics and Physics of Complex Systems departments

    Israel Quantum Information Theory Day

    Date:
    21
    Wednesday
    December
    2022
    Lecture / Seminar
    Time: 09:30
    Location: The David Lopatie Conference Centre
    Organizer: The Center for Quantum Science and Technology
    Abstract: The Israel Quantum Information Theory day brings together researchers, postdocto ... Read more The Israel Quantum Information Theory day brings together researchers, postdoctoral scholars and Ph.D. students from Israel working on the theory of quantum computation and information processing for a day of scientific talks, research discussions and social interaction. Registration: https://tinyurl.com/2rxsuykb
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    Gallery: Israel Quantum Information Theory Day 2022
    Israel Quantum Information Theory Day Lecture / Seminar website

    Quantum Bits: The Quantum Simulation & Quantum Computing Edition

    Date:
    11
    Friday
    November
    2022
    Lecture / Seminar
    Time: 16:00-17:00
    Location: Online: https://www.mcqst.de/news-and-events/events/quantum-bits.html

    The emerging quantum industry in Israel

    Date:
    26
    Wednesday
    October
    2022
    Lecture / Seminar
    Time: 14:00-15:30
    Location: Weismann auditorium
    Organizer: AMOTech club

    Simulations and experiments with IBM quantum devices -- Haggai Landa (IBM)

    Date:
    15
    Wednesday
    June
    2022
    Lecture / Seminar
    Time: 10:45-12:00
    Location: Physics library, Benoziyo Physics building

    Quantum Bits: Quantum Communications

    Date:
    23
    Wednesday
    February
    2022
    Lecture / Seminar
    Time: 18:00-19:00
    Location: Online: https://www.mcqst.de/news-and-events/events/quantum-bits.html

    Engineering quantum processors and quantum networks atom-by-atom -- Prof. Hannes Bernien (University of Chicago)

    Date:
    16
    Thursday
    December
    2021
    Colloquium
    Time: 11:00-12:00
    Location: Weissman Auditorium