Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics

We present exact results on a novel kind of emergent random matrix universality that quantum many-body systems at infinite temperature can exhibit. Specifically, we consider an ensemble of pure states supported on a small subsystem, generated from projective measurements of the remainder of the...

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Main Authors: Ho, Wen Wei, Choi, Soonwon
Other Authors: Massachusetts Institute of Technology. Center for Theoretical Physics
Format: Article
Language:English
Published: American Physical Society (APS) 2022
Online Access:https://hdl.handle.net/1721.1/141460
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author Ho, Wen Wei
Choi, Soonwon
author2 Massachusetts Institute of Technology. Center for Theoretical Physics
author_facet Massachusetts Institute of Technology. Center for Theoretical Physics
Ho, Wen Wei
Choi, Soonwon
author_sort Ho, Wen Wei
collection MIT
description We present exact results on a novel kind of emergent random matrix universality that quantum many-body systems at infinite temperature can exhibit. Specifically, we consider an ensemble of pure states supported on a small subsystem, generated from projective measurements of the remainder of the system in a local basis. We rigorously show that the ensemble, derived for a class of quantum chaotic systems undergoing quench dynamics, approaches a universal form completely independent of system details: it becomes uniformly distributed in Hilbert space. This goes beyond the standard paradigm of quantum thermalization, which dictates that the subsystem relaxes to an ensemble of quantum states that reproduces the expectation values of local observables in a thermal mixed state. Our results imply more generally that the distribution of quantum states themselves becomes indistinguishable from those of uniformly random ones, i.e. the ensemble forms a quantum state-design in the parlance of quantum information theory. Our work establishes bridges between quantum many-body physics, quantum information and random matrix theory, by showing that pseudo-random states can arise from isolated quantum dynamics, opening up new ways to design applications for quantum state tomography and benchmarking.
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spelling mit-1721.1/1414602023-01-26T21:52:06Z Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics Ho, Wen Wei Choi, Soonwon Massachusetts Institute of Technology. Center for Theoretical Physics We present exact results on a novel kind of emergent random matrix universality that quantum many-body systems at infinite temperature can exhibit. Specifically, we consider an ensemble of pure states supported on a small subsystem, generated from projective measurements of the remainder of the system in a local basis. We rigorously show that the ensemble, derived for a class of quantum chaotic systems undergoing quench dynamics, approaches a universal form completely independent of system details: it becomes uniformly distributed in Hilbert space. This goes beyond the standard paradigm of quantum thermalization, which dictates that the subsystem relaxes to an ensemble of quantum states that reproduces the expectation values of local observables in a thermal mixed state. Our results imply more generally that the distribution of quantum states themselves becomes indistinguishable from those of uniformly random ones, i.e. the ensemble forms a quantum state-design in the parlance of quantum information theory. Our work establishes bridges between quantum many-body physics, quantum information and random matrix theory, by showing that pseudo-random states can arise from isolated quantum dynamics, opening up new ways to design applications for quantum state tomography and benchmarking. 2022-04-01T15:33:21Z 2022-04-01T15:33:21Z 2022-02-11 2022-04-01T15:27:13Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/141460 Ho, Wen Wei and Choi, Soonwon. 2022. "Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics." Physical Review Letters, 128 (6). en 10.1103/physrevlett.128.060601 Physical Review Letters Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Physical Society (APS) APS
spellingShingle Ho, Wen Wei
Choi, Soonwon
Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title_full Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title_fullStr Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title_full_unstemmed Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title_short Exact Emergent Quantum State Designs from Quantum Chaotic Dynamics
title_sort exact emergent quantum state designs from quantum chaotic dynamics
url https://hdl.handle.net/1721.1/141460
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