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arXiv 1910.04769cond-mat.stat-mechcond-mat.dis-nnhep-thquant-ph
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Sherrington-Kirkpatrick模型中的量子回波动力学

Quantum echo dynamics in the Sherrington-Kirkpatrick model

Silvia Pappalardi, Anatoli Polkovnikov, Alessandro Silva

摘要:

理解量子多体系统中混沌的足迹已经争论了很长时间。本文研究了具有横向场的Sherrington-Kirkpatrick(SK)模型在有效时间反演下的回波动力学。我们数值研究了它的量子和半经典动力学。我们探讨了如何混沌多体量子物理可以导致指数发散的回声的观察,我们表明,这是一个结果的三个要求:i)集体性质的观察,ii)一个适当选择的初始状态和iii)存在一个定义良好的混沌半经典(大- $N$)限制。在这些条件下,回波以指数方式增长到Efeste时间,Efeste时间与自旋数$N$成比例。在这种情况下,回波很好地描述了半经典(截断维格纳)近似。我们还讨论了SK模型的一个短程版本,其中的Escherichfest时间不依赖于$N$和量子回波只显示多项式增长。我们的研究结果提供了新的见解扰乱和回声动力学,以及如何观察它的实验。

英文摘要:

Understanding the footprints of chaos in quantum-many-body systems has been under debate for a long time. In this work, we study the echo dynamics of the Sherrington-Kirkpatrick (SK) model with transverse field under effective time reversal. We investigate numerically its quantum and semiclassical dynamics. We explore how chaotic many-body quantum physics can lead to exponential divergence of the echo of observables and we show that it is a result of three requirements: i) the collective nature of the observable, ii) a properly chosen initial state and iii) the existence of a well-defined chaotic semi-classical (large-$N$) limit. Under these conditions, the echo grows exponentially up to the Ehrenfest time, which scales logarithmically with the number of spins $N$. In this regime, the echo is well described by the semiclassical (truncated Wigner) approximation. We also discuss a short-range version of the SK model, where the Ehrenfest time does not depend on $N$ and the quantum echo shows only polynomial growth. Our findings provide new insights on scrambling and echo dynamics and how to observe it experimentally.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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