Scrambling and thermalization in a diffusive quantum manybody system
Outoftime ordered (OTO) correlation functions describe scrambling of information in correlated quantum matter. They are of particular interest in incoherent quantum systems lacking well defined quasiparticles. Thus far, it is largely elusive how OTO correlators spread in incoherent systems with diffusive transport governed by a few globally conserved quantities. Here, we study the dynamical response of such a system using highperformance matrixproductoperator techniques. Specifically, we consider the nonintegrable, onedimensional Bose–Hubbard model in the incoherent hightemperature regime. Our system exhibits diffusive dynamics in timeordered correlators of globally conserved quantities, whereas OTO correlators display a ballistic, lightcone spreading of quantum information. The slowest process in the global thermalization of the system is thus diffusive, yet information spreading is not inhibited by such slow dynamics. We furthermore develop an experimentally feasible protocol to overcome some challenges faced by existing proposals and to probe timeordered and OTO correlation functions. As a result, our study opens new avenues for both the theoretical and experimental exploration of thermalization and information scrambling dynamics.
 Authors:

^{[1]};
^{[2]}
;
^{[3]};
^{[4]}
 Technical Univ. of Munich, Garching (Germany); Harvard Univ., Cambridge, MA (United States)
 SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
 California Inst. of Technology (CalTech), Pasadena, CA (United States)
 Technical Univ. of Munich, Garching (Germany)
 Publication Date:
 Grant/Contract Number:
 AC0276SF00515; KN 1254/11; 291763
 Type:
 Accepted Manuscript
 Journal Name:
 New Journal of Physics
 Additional Journal Information:
 Journal Volume: 19; Journal Issue: 6; Journal ID: ISSN 13672630
 Publisher:
 IOP Publishing
 Research Org:
 SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; scrambling of quantum information; outoftime ordered correlation functions; incoherent transport; manybody interferometry
 OSTI Identifier:
 1369417
Bohrdt, A., Mendl, C. B., Endres, M., and Knap, M.. Scrambling and thermalization in a diffusive quantum manybody system. United States: N. p.,
Web. doi:10.1088/13672630/aa719b.
Bohrdt, A., Mendl, C. B., Endres, M., & Knap, M.. Scrambling and thermalization in a diffusive quantum manybody system. United States. doi:10.1088/13672630/aa719b.
Bohrdt, A., Mendl, C. B., Endres, M., and Knap, M.. 2017.
"Scrambling and thermalization in a diffusive quantum manybody system". United States.
doi:10.1088/13672630/aa719b. https://www.osti.gov/servlets/purl/1369417.
@article{osti_1369417,
title = {Scrambling and thermalization in a diffusive quantum manybody system},
author = {Bohrdt, A. and Mendl, C. B. and Endres, M. and Knap, M.},
abstractNote = {Outoftime ordered (OTO) correlation functions describe scrambling of information in correlated quantum matter. They are of particular interest in incoherent quantum systems lacking well defined quasiparticles. Thus far, it is largely elusive how OTO correlators spread in incoherent systems with diffusive transport governed by a few globally conserved quantities. Here, we study the dynamical response of such a system using highperformance matrixproductoperator techniques. Specifically, we consider the nonintegrable, onedimensional Bose–Hubbard model in the incoherent hightemperature regime. Our system exhibits diffusive dynamics in timeordered correlators of globally conserved quantities, whereas OTO correlators display a ballistic, lightcone spreading of quantum information. The slowest process in the global thermalization of the system is thus diffusive, yet information spreading is not inhibited by such slow dynamics. We furthermore develop an experimentally feasible protocol to overcome some challenges faced by existing proposals and to probe timeordered and OTO correlation functions. As a result, our study opens new avenues for both the theoretical and experimental exploration of thermalization and information scrambling dynamics.},
doi = {10.1088/13672630/aa719b},
journal = {New Journal of Physics},
number = 6,
volume = 19,
place = {United States},
year = {2017},
month = {6}
}