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Proposal for measuring out-of-time-ordered correlators at finite temperature with coupled spin chains

Sundar, Bhuvanesh and Elben, Andreas and Joshi, Lata Kh. and Zache, Torsten V. (2022) Proposal for measuring out-of-time-ordered correlators at finite temperature with coupled spin chains. New Journal of Physics, 24 (2). Art. No. 023037. ISSN 1367-2630. doi:10.1088/1367-2630/ac5002.

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Information scrambling, which is the spread of local information through a system’s many-body degrees of freedom, is an intrinsic feature of many-body dynamics. In quantum systems, the out-of-time-ordered correlator (OTOC) quantifies information scrambling. Motivated by experiments that have measured the OTOC at infinite temperature and a theory proposal to measure the OTOC at finite temperature using the thermofield double state, we describe a protocol to measure the OTOC in a finite temperature spin chain that is realized approximately as one half of the ground state of two moderately-sized coupled spin chains. We consider a spin Hamiltonian with particle–hole symmetry, for which we show that the OTOC can be measured without needing sign-reversal of the Hamiltonian. We describe a protocol to mitigate errors in the estimated OTOC, arising from the finite approximation of the system to the thermofield double state. We show that our protocol is also robust to main sources of decoherence in experiments.

Item Type:Article
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URLURL TypeDescription Paper
Sundar, Bhuvanesh0000-0002-8867-360X
Elben, Andreas0000-0003-1444-6356
Joshi, Lata Kh.0000-0001-7523-0781
Zache, Torsten V.0000-0003-3549-7160
Additional Information:© 2022 The Author(s). Published by IOP Publishing Ltd on behalf of the Institute of Physics and Deutsche Physikalische Gesellschaft. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 12 July 2021. Revised 29 December 2021. Accepted 28 January 2022. Published 25 February 2022. Work in Innsbruck was supported by the innovation program under the Grant Agreement No. 731473 (FWF QuantERA via QTFLAG I03769), from the Austrian Science Foundation (FWF, P 32597 N) and by the Simons Collaboration on UltraQuantum Matter, which is a grant from the Simons Foundation (651440, PZ). AE acknowledges funding by the German National Academy of Sciences Leopoldina under the Grant No. LPDS 2021-02. We thank Ana Maria Rey and Murray Holland for a careful reading of the manuscript. We thank Norbert Linke, Alaina Green, and Benoit Vermersch for valuable discussions and comments on the manuscript. Data availability statement. All data that support the findings of this study are included within the article (and any supplementary files).
Group:Institute for Quantum Information and Matter, Walter Burke Institute for Theoretical Physics
Funding AgencyGrant Number
European Research Council (ERC)731473
FWF Der Wissenschaftsfonds32597
Simons Foundation651440
Deutsche Akademie der Naturforscher LeopoldinaLPDS 2021-02
Issue or Number:2
Record Number:CaltechAUTHORS:20220225-724707000
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Official Citation:Bhuvanesh Sundar et al 2022 New J. Phys. 24 023037
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:113616
Deposited By: George Porter
Deposited On:25 Feb 2022 20:36
Last Modified:12 Jul 2022 19:51

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