Michel, Thomas R. and Urbina, Juan Diego and Schlagheck, Peter (2025) Quasiclassical theory of out-of-time-ordered correlators. JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL, 58 (27): 275303. ISSN 1751-8113, 1751-8121
Full text not available from this repository. (Request a copy)Abstract
Out-of-time-ordered correlators (OTOCs), defined via the squared commutator of a time-evolving and a stationary operator, represent observables that provide useful indicators for chaos and the scrambling of information in complex quantum systems. Here we present a quasiclassical formalism of OTOCs, which is obtained from the semiclassical van Vleck-Gutzwiller propagator through the application of the diagonal approximation. For short evolution times, this quasiclassical approach yields the same result as the Wigner-Moyal formalism, i.e. OTOCs are classically described via the square of the Poisson bracket between the two involved observables, thus giving rise to an exponential growth in a chaotic regime. For long times, for which the semiclassical framework is, in principle, still valid, the diagonal approximation yields an asymptotic saturation value for the quasiclassical OTOC under the assumption of fully developed classical chaos. However, numerical simulations, carried out within chaotic few-site Bose-Hubbard systems in the absence and presence of periodic driving, demonstrate that this saturation value strongly underestimates the actual threshold value of the quantum OTOC, which is normally attained after the Ehrenfest time. This indicates that nondiagonal and hence genuinely quantum contributions, thus exceeding the framework of the quasiclassical description, are primarily responsible for describing OTOCs beyond the short-time regime.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | SEMICLASSICAL THEORY; QUANTUM; APPROXIMATION; PHYSICS; CHAOS; SPACE; quantum chaos; out-of-time-order correlators; Bose-Hubbard; semiclassical; diagonal approximation; quasiclassical |
| Subjects: | 500 Science > 530 Physics |
| Divisions: | Physics > Institute of Theroretical Physics > Chair Professor Richter > Group Klaus Richter |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 18 Jun 2026 08:11 |
| Last Modified: | 18 Jun 2026 08:11 |
| URI: | https://pred.uni-regensburg.de/id/eprint/66729 |
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