English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Fast scrambling of quantum correlations, reflected by the exponential growthof Out-of-Time-Order Correlators (OTOCs) on short pre-Ehrenfest time scales, iscommonly considered as a major quantum signature of unstable dynamics inquantum systems with a classical limit. In two recent works [Phys. Rev. Lett.123, 160401 (2019)] and [Phys. Rev. Lett. 124, 140602 (2020)], a significantdifference in the scrambling rate of integrable (many-body) systems wasobserved, depending on the initial state being semiclassically localized aroundunstable fixed points or fully delocalized (infinite temperature).Specifically, the quantum Lyapunov exponent $\lambda_{\rm q}$ quantifying theOTOC growth is given, respectively, by $\lambda_{\rm q}=2\lambda_{\rm s}$ or$\lambda_{\rm q}=\lambda_{\rm s}$ in terms of the stability exponent$\lambda_{\rm s}$ of the hyperbolic fixed point. Here we show that a wavepacket, initially localized around this fixed point, features a distinctdynamical transition between these two regions. We present an analyticalsemiclassical approach providing a physical picture of this phenomenon andsupport our findings by extensive numerical simulations in the whole parameterrange of locally unstable dynamics of a Bose-Hubbard dimer. Our results suggestthat the existence of this crossover is a hallmark of unstable separatrixdynamics in integrable systems, thus opening the possibility to distinguish thelatter, on the basis of this particular observable, from genuine chaoticdynamics generally featuring uniform exponential growth of the OTOC.

Dynamical transition from localized to uniform scrambling in locally hyperbolic systems