Format results
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Talk
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Direct experimental reconstruction of the Bloch sphere
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Michael Mazurek Institute for Quantum Computing (IQC)
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Matthew Pusey University of York
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Single-photon test of Hyper-Complex Quantum Theories
Lorenzo Procopio University of Vienna
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Experimental implementation of quantum-coherent mixtures of causal relations
Robert Spekkens Perimeter Institute for Theoretical Physics
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Talk
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Does relativistic causality constrain interference phenomena?
Markus Müller Institute for Quantum Optics and Quantum Information (IQOQI) - Vienna
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Talk
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QI Basics - 1
Patrick Hayden Stanford University
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Gravity Basics - 1
Veronika Hubeny University of California, Davis
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Entanglement - 1
Robert Spekkens Perimeter Institute for Theoretical Physics
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A new perspective on holographic entanglement
Matthew Headrick Brandeis University
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Bell’s Theorem
Adrian Kent University of Cambridge
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GR: Actions and Equations
David Kubiznak Charles University
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QI Basics - 2
John Watrous IBM (Canada)
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Talk
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Welcome and Opening Remarks
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Marina Cortes Institute for Astrophysics and Space Sciences
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Lee Smolin Perimeter Institute for Theoretical Physics
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Neil Turok University of Edinburgh
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The origin of arrows of time II
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Sean Carroll California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy
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Marina Cortes Institute for Astrophysics and Space Sciences
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Tim Koslowski Technical University of Applied Sciences Würzburg-Schweinfurt
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The origin of arrows of time II cont.
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Sean Carroll California Institute of Technology (Caltech) - Division of Physics Mathematics & Astronomy
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Marina Cortes Institute for Astrophysics and Space Sciences
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Tim Koslowski Technical University of Applied Sciences Würzburg-Schweinfurt
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Testing time asymmetry in the early universe
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Brian Keating University of California, San Diego
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Andrew Liddle University of Lisbon
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Richard Muller University of California, Berkeley
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The fate of the big bang
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Abhay Ashtekar Pennsylvania State University
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Neil Turok University of Edinburgh
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Time as Organization – Downward Caustation, Structure and Complexity I
Barbara Drossel Technische Universität Darmstadt
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Time as Organization – Downward Caustation, Structure and Complexity II
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Stuart Kauffman Santa Fe Institute
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George Ellis University of Cape Town
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Talk
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Finally making sense of Quantum Mechanics, part 1
Yakir Aharonov Chapman University
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How to count one photon and get a(n average) result of 1000...
Aephraim Steinberg University of Toronto
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The Quantum Tip of the Two-Vector Iceberg
Avshalom Elitzur Chapman University
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The arrow of time for continuous quantum measurements
Andrew Jordan University of Rochester
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Observation of Aharonov-Bohm effect with quantum tunneling
Yutaka Shikano Institute for Molecular Science, National Institutes of Natural Sciences
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Talk
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Protective Measurement and Ergodicity
Yakir Aharonov Chapman University
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Sudden Sharp Forces and Nonlocal Interactions
Yakir Aharonov Chapman University
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Talk
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Gravity Dual of Quantum Information Metric
Tadashi Takayanagi Yukawa Institute for Theoretical Physics
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A new perspective on holographic entanglement
Matthew Headrick Brandeis University
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Universal holographic description of CFT entanglement entropy
Thomas Faulkner University of Illinois Urbana-Champaign
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Geometric Constructs in AdS/CFT
Veronika Hubeny University of California, Davis
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Do black holes create polyamory
Jonathan Oppenheim University College London
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Tensor Network Renormalization and the MERA
Glen Evenbly Georgia Institute of Technology
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Entanglement renormalization for quantum fields
Jutho Haegeman Ghent University
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Holographic quantum error-correcting codes: Toy models for the bulk/boundary correspondence
Fernando Pastawski California Institute of Technology
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von Neumann algebraic quantum information theory and entanglement in infinite quantum systems
Lauritz van Luijk Leibniz University Hannover
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Learning and testing quantum states of fermionic systems
Antonio Mele Freie Universität Berlin
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A Criterion for Post-Selected Quantum Advantage
Matthew Fox University of Colorado Boulder
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Experimental Quantum Foundations
Experimental Quantum Foundations -
Formulating and Finding Higher-Order Interference
Formulating and Finding Higher-Order Interference
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Concepts and Paradoxes in a Quantum Universe
Concepts and Paradoxes in a Quantum Universe
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Quantum Information in Quantum Gravity II
Quantum Information in Quantum Gravity II -
von Neumann algebraic quantum information theory and entanglement in infinite quantum systems
Lauritz van Luijk Leibniz University Hannover
In quantum systems with infinitely many degrees of freedom, states can be infinitely entangled across a pair of subsystems. But are there different forms of infinite entanglement? In the first part of my talk, I will present a von Neumann algebraic framework for studying information-theoretic properties of infinite systems. Using this framework, we find operational tasks that distinguish different forms of infinite entanglement, and, by analysing these tasks, we show that the type classification of von Neumann algebras (types I, II, III, and their respective subtypes) is in 1-to-1 correspondence with operational entanglement properties. Our findings promote the type classification from mere algebraic bookkeeping to a classification of infinite quantum systems based on their operational entanglement properties. In the second part, I will discuss what is known about the type classification of the von Neumann algebras arising in quantum many-body systems. Together with our results, this identifies new operational properties, e.g., embezzlement of entanglement, of well-known physical models, e.g., the critical transverse-field Ising chain or suitable Levin-Wen models. Joint work with: Alexander Stottmeister, Reinhard F. Werner, and Henrik Wilming -
Approximate entropy accumulation
Frédéric DupuisThe entropy accumulation theorem (EAT) allows us to lower bound the min-entropy of a state that can be generated by a chain of quantum channels satisfying a Markov chain condition, and can be used to prove the security of QKD protocols, including device-independent ones. However, one of its drawbacks is that it only applies to states with a fairly rigid structure; in particular, the Markov chain condition must be satisfied exactly. What happens when we relax this assumption by allowing the required structure to be satisfies only approximately? Does doing so lead to interesting applications? We answer both questions by the affirmative: we present two flavours of approximate EAT, and show that it can be used to prove the security of parallel device-independent QKD, and to analyze QKD protocols under source correlations. Along the way, we will introduce the concept of "approximation chain" which underpins the new results. This is joint work with Ashutosh Marwah; the talk will cover material from 2412.06723, 2402.12346, and 2308.11736. -
Self testing in General Probabilistic Theories
Lionel DmelloThis talk will consist of two parts. In the former I discuss published work [LD, Ligthart, Gross, PRA, 2024], and in the latter some new related results. Part 1 -- Although there exist theories with "stronger bipartite entanglement" than quantum mechanics (QM), in sense that they have a larger CHSH value than Tsirelson's bound for QM, all such theories known tend to come at a cost, namely, they have strictly weaker bipartite measurements. Thus it has been conjectured that if one looks at scenarios where the correlations depend both on bipartite states and bipartite measurements, e.g. entanglement swapping, such theories cannot beat QM. However, in our recent work [LD, Ligthart, Gross, PRA, 2024], we constructed a General Probabilistic Theory (GPT) -- Oblate Stabilizer Theory (OST) -- that can both achieve a CHSH value of 4 (the mathematical maximum), and maintain this CHSH value after arbitrarily many rounds of entanglement swapping, effectively ruling out this conjecture. Part 2 -- One particularly non-intuitive feature of OST (for those in the know) is the presence of a "spurious extra dimension" in the local theory: Even though the CHSH violation involves only a two-dimensional section of local state space, we failed to make the entanglement swapping property work without going to three dimensions. In ongoing work, we managed to identify the mechanism behind this phenomenon. To this end, we have introduced a notion of self-testing for GPTs, and, using this we have established a GPT version of the "no-pancake" theorem that says that there is no completely positive map that maps the Bloch sphere to a two-dimensional section. Further, under reasonable assumptions, we have also managed to establish the uniqueness of OST, and provide a prescription for the construction of GPTs capable of stable iterated entanglement swapping. -
Learning and testing quantum states of fermionic systems
Antonio Mele Freie Universität Berlin
Abstract: The experimental realization of increasingly complex quantum states in quantum devices underscores the pressing need for new methods of state learning and verification. Among the various classes of quantum states, fermionic systems hold particular significance due to their crucial roles in physics. Despite their importance, research on learning quantum states of fermionic systems remains surprisingly limited. In our work, we aim to present a comprehensive rigorous study on learning and testing states of fermionic systems. We begin by analyzing arguably the simplest important class of fermionic states—free-fermionic states—and subsequently extend our analysis to more complex fermionic states. We meticulously delineate scenarios in which efficient algorithms are feasible, providing experimentally practical algorithms for these cases, while also identifying situations where any algorithm for solving these problems must be inherently inefficient. At the same time, we present novel fundamental results of independent interest on fermionic systems, with additional applications beyond learning and characterizing quantum devices, such as many-body physics, resource theory of non-Gaussianity, and circuit compilation strategies. (Talk based on https://arxiv.org/pdf/2409.17953 , https://arxiv.org/pdf/2402.18665) -
A Criterion for Post-Selected Quantum Advantage
Matthew Fox University of Colorado Boulder
Assuming the polynomial hierarchy is infinite, we prove a sufficient condition for determining if uniform and polynomial size quantum circuits over a non-universal gate set are not efficiently classically simulable in the weak multiplicative sense. Our criterion exploits the fact that subgroups of SL(2; C) are essentially either discrete or dense in SL(2; C). Using our criterion, we give a new proof that both instantaneous quantum polynomial (IQP) circuits and conjugated Clifford circuits (CCCs) afford a quantum advantage. We also prove that both commuting CCCs and CCCs over various fragments of the Clifford group afford a quantum advantage, which settles two questions of Bouland, Fitzsimons, and Koh. Our results imply that circuits made of just U \otimes U-conjugated CZ gates afford a quantum advantage for almost all single-qubit unitaries U.