论文标题
非平衡BCS模型中的动态量子相变和复发
Dynamical Quantum Phase transitions and Recurrences in the Non-Equilibrium BCS model
论文作者
论文摘要
BCS模型的非平衡方面几十年来一直着迷于物理学家，从Eliashberg的开创性作品到冷原子实验中的现代实现。后一种情况引起了人们对fermions和配对互动的淬火动态的极大兴趣。最近引入的动态量子相变的概念是试图对无数现象进行分类，这可能导致远离平衡系统。这些被定义为Loschmidt Echo对数的非分析点，并与动力学A系统顺序参数中的振荡相关。在这项工作中，我们分析研究了BCS模型淬火中DQPTS与超导顺序参数的振荡之间的关系。我们发现，订单参数的每个振荡都伴随着DQPT，该DQPT本质上是第一阶。我们向多种初始状态显示了这一点，此外发现，当顺序参数达到恒定稳态时，就不会发生DQPT。
Non-equilibrium aspects of the BCS model have fascinated physicists for decades, from the seminal works of Eliashberg to modern realizations in cold atom experiments. The latter scenarios have lead to a great deal of interest in the quench dynamics of fermions with pairing interactions. The recently introduced notion of a dynamical quantum phase transition is an attempt to classify the myriad of possible phenomena which can result in such far from equilibrium systems. These are defined as non-analytic points of the logarithm of the Loschmidt echo and are linked to oscillations in the dynamics a systems order parameter. In this work we analytically investigate the relation between DQPTs and oscillation of the superconducting order parameter in quenches of the BCS model. We find that each oscillation of the order parameter is accompanied by a DQPT which is first order in nature. We show this for a variety of initial states and furthermore find that when the order parameter attains a constant steady state then no DQPTS occur.
