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

Integrable quantum systems of finite size are generically robust against weakenough integrability-breaking perturbations, but become quantum chaotic andthermalizing if the integrability-breaking is strong enough. We argue that theonset of quantum chaos can be described as a Fock-space delocalization process,with the eigenstates of the integrable system being taken as the "Fock states".The integrability-breaking perturbation introduces hopping in this Fock space,and chaos sets in when this hopping delocalizes the many-body eigenstates inthis space. Depending on the range of the dominant Fock-space hopping,delocalization can occur either through a crossover, or via a transition thatbecomes sharp in the appropriate large-system dynamic limit. In either case,the perturbation strength at the onset of chaos scales to zero in the usualthermodynamic limit, with a size-dependence that we estimate analytically andcompute numerically for a few specific models. We also identify twointermediate finite-size-dependent regimes: There is generally an intermediatenonchaotic regime in which integrability is broken strongly enough to producesome system-wide many-body resonances but not enough to thermalize the system.In spatially extended systems (but not in quantum dots) there is also acrossover or transition between chaotic regimes where the ratio of the systemsize to the mean free path of the quasiparticles of the integrable system issmall versus large compared to unity.

Onset of many-body quantum chaos due to breaking integrability