Kiendl Thomas, Marquardt Florian
Dahlem Center for Complex Quantum Systems and Institut für Theoretische Physik, Freie Universität Berlin, 14195, Berlin, Germany.
Institute for Theoretical Physics, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany.
Phys Rev Lett. 2017 Mar 31;118(13):130601. doi: 10.1103/PhysRevLett.118.130601. Epub 2017 Mar 30.
After a quench in a quantum many-body system, expectation values tend to relax towards long-time averages. However, temporal fluctuations remain in the long-time limit, and it is crucial to study the suppression of these fluctuations with increasing system size. The particularly important case of nonintegrable models has been addressed so far only by numerics and conjectures based on analytical bounds. In this work, we are able to derive analytical predictions for the temporal fluctuations in a nonintegrable model (the transverse Ising chain with extra terms). Our results are based on identifying a dynamical regime of "many-particle dephasing," where quasiparticles do not yet relax but fluctuations are nonetheless suppressed exponentially by weak integrability breaking.
在量子多体系统中猝灭后，期望值倾向于朝着长时间平均值弛豫。然而，长时间极限下仍存在时间涨落，研究随着系统尺寸增加这些涨落的抑制情况至关重要。到目前为止，非可积模型这个特别重要的情况仅通过基于解析界的数值计算和推测来处理。在这项工作中，我们能够推导非可积模型（带有额外项的横向伊辛链）中时间涨落的解析预测。我们的结果基于识别一种“多粒子退相”的动力学区域，其中准粒子尚未弛豫，但涨落仍因弱可积性破坏而被指数抑制。
