动力学淬火过程中的不动点及衍生拓扑现象

本文对近两年来有关淬火动力学过程中拓扑现象的研究做简要综述.这些动力学拓扑现象被动力学过程中的衍生拓扑不变量保护,与淬火前后体系的拓扑性质有密切关系.基于人工量子模拟平台的高度可控性,已在诸如超冷原子、超导量子比特、核磁共振、线性光学等众多物理体系中,通过对人工拓扑体系动力学过程的调控,观测到如动力学涡旋、动量-时间域的Hopf映射及环绕数、拓扑保护的自旋环结构、动力学量子相变、动量-时间斯格明子等诸多动力学拓扑现象.其中某些拓扑结构还可以在非幺正动力学淬火过程中稳定存在.这些研究将人们对拓扑物相的认识和研究从平衡态推广到非平衡动力学领域,具有重要的科学价值.

Fixed points and dynamic topological phenomena in quench dynamics

In this review, we discuss the recent progress on the study of dynamic topological phenomena in quench dynamics. In particular, we focus on dynamic quantum phase transition and dynamic topological invariant, both of which are hinged upon the existence of fixed points in the dynamics. Further, the existence of these fixed points are topologically protected, in the sense that their existence are closely related to static topological invariants of pre- and post-quench Hamiltonians. We also discuss under what condition these dynamic topological phenomena are robust in non-unitary quench dynamics governed by non-Hermitian Hamiltonians. So far, dynamic topological phenomena have been experimentally observed in synthetic systems such as cold atomic gases, superconducting qubits, and linear optics. These studies extend our understanding of topological matter to the non-equilibrium regime.