Chaos and complexity by design

Abstract We study the relationship between quantum chaos and pseudorandomness by developing probes of unitary design. A natural probe of randomness is the “frame poten-tial,” which is minimized by unitary k-designs and measures the 2-norm distance between the Haar random unitary ensemble and another...

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Main Authors: Daniel A. Roberts, Beni Yoshida
Format: Article
Language:English
Published: SpringerOpen 2017-04-01
Series:Journal of High Energy Physics
Subjects:
Online Access:http://link.springer.com/article/10.1007/JHEP04(2017)121
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author Daniel A. Roberts
Beni Yoshida
author_facet Daniel A. Roberts
Beni Yoshida
author_sort Daniel A. Roberts
collection DOAJ
description Abstract We study the relationship between quantum chaos and pseudorandomness by developing probes of unitary design. A natural probe of randomness is the “frame poten-tial,” which is minimized by unitary k-designs and measures the 2-norm distance between the Haar random unitary ensemble and another ensemble. A natural probe of quantum chaos is out-of-time-order (OTO) four-point correlation functions. We show that the norm squared of a generalization of out-of-time-order 2k-point correlators is proportional to the kth frame potential, providing a quantitative connection between chaos and pseudorandomness. Additionally, we prove that these 2k-point correlators for Pauli operators completely determine the k-fold channel of an ensemble of unitary operators. Finally, we use a counting argument to obtain a lower bound on the quantum circuit complexity in terms of the frame potential. This provides a direct link between chaos, complexity, and randomness.
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spelling doaj.art-33cdf49d7bff416baaa57f371a3a56dd2022-12-22T00:06:37ZengSpringerOpenJournal of High Energy Physics1029-84792017-04-012017416410.1007/JHEP04(2017)121Chaos and complexity by designDaniel A. Roberts0Beni Yoshida1Center for Theoretical Physics and Department of Physics, Massachusetts Institute of TechnologyPerimeter Institute for Theoretical PhysicsAbstract We study the relationship between quantum chaos and pseudorandomness by developing probes of unitary design. A natural probe of randomness is the “frame poten-tial,” which is minimized by unitary k-designs and measures the 2-norm distance between the Haar random unitary ensemble and another ensemble. A natural probe of quantum chaos is out-of-time-order (OTO) four-point correlation functions. We show that the norm squared of a generalization of out-of-time-order 2k-point correlators is proportional to the kth frame potential, providing a quantitative connection between chaos and pseudorandomness. Additionally, we prove that these 2k-point correlators for Pauli operators completely determine the k-fold channel of an ensemble of unitary operators. Finally, we use a counting argument to obtain a lower bound on the quantum circuit complexity in terms of the frame potential. This provides a direct link between chaos, complexity, and randomness.http://link.springer.com/article/10.1007/JHEP04(2017)121AdS-CFT CorrespondenceGauge-gravity correspondenceRandom SystemsHolography and condensed matter physics (AdS/CMT)
spellingShingle Daniel A. Roberts
Beni Yoshida
Chaos and complexity by design
Journal of High Energy Physics
AdS-CFT Correspondence
Gauge-gravity correspondence
Random Systems
Holography and condensed matter physics (AdS/CMT)
title Chaos and complexity by design
title_full Chaos and complexity by design
title_fullStr Chaos and complexity by design
title_full_unstemmed Chaos and complexity by design
title_short Chaos and complexity by design
title_sort chaos and complexity by design
topic AdS-CFT Correspondence
Gauge-gravity correspondence
Random Systems
Holography and condensed matter physics (AdS/CMT)
url http://link.springer.com/article/10.1007/JHEP04(2017)121
work_keys_str_mv AT danielaroberts chaosandcomplexitybydesign
AT beniyoshida chaosandcomplexitybydesign