Experimental Determination of Dynamical Lee-Yang Zeros
Experimental Determination of Dynamical Lee-Yang Zeros
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DOI：
10.1103/physrevlett.118.180601
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发表时间：
2017-05-04
影响因子：
8.6
通讯作者：
Flindt, Christian
中科院分区：
文献类型：
--
作者：
Brandner, Kay;Maisi, Ville F.;Flindt, Christian
统计物理学提供了解释相互作用多体系统相行为的概念和方法。对Lee-Yang零点--有限大小系统中自由能的复奇点--的研究导致了对平衡相变的统一理解。然而，李和杨的观点并不局限于均衡现象。最近，Lee-Yang零点被用来描述非平衡过程，如量子系统失超后的动态相变或玻璃中的动态有序-无序相变。在这里，我们在实验上实现了一种在这种非平衡设置下确定Lee-Yang零点的方案。通过对轨道上的动力学活动的测量，我们提取了一个包含安德列夫隧道的随机过程的动力学Lee-Yang零点。根据李-杨零点的短期行为，我们预测了通常难以测量的活动的大偏差统计。我们的方法为进一步实验失去平衡的多体系统的统计力学铺平了道路。
Statistical physics provides the concepts and methods to explain the phase behavior of interacting many-body systems. Investigations of Lee-Yang zeros-complex singularities of the free energy in systems of finite size-have led to a unified understanding of equilibrium phase transitions. The ideas of Lee and Yang, however, are not restricted to equilibrium phenomena. Recently, Lee-Yang zeros have been used to characterize nonequilibrium processes such as dynamical phase transitions in quantum systems after a quench or dynamic order-disorder transitions in glasses. Here, we experimentally realize a scheme for determining Lee-Yang zeros in such nonequilibrium settings. We extract the dynamical Lee-Yang zeros of a stochastic process involving Andreev tunneling between a normal-state island and two superconducting leads from measurements of the dynamical activity along a trajectory. From the short-time behavior of the Lee-Yang zeros, we predict the large-deviation statistics of the activity which is typically difficult to measure. Our method paves the way for further experiments on the statistical mechanics of many-body systems out of equilibrium.