Beijing Computational Science Research Center, Beijing 100084, China.
Department of Physics, Southeast University, Nanjing 211189, China.
Phys Rev Lett. 2019 Jan 18;122(2):020501. doi: 10.1103/PhysRevLett.122.020501.
Signaled by nonanalyticities in the time evolution of physical observables, dynamic quantum phase transitions (DQPTs) emerge in quench dynamics of topological systems and possess an interesting geometric origin captured by dynamic topological order parameters (DTOPs). In this Letter, we report the experimental study of DQPTs using discrete-time quantum walks of single photons. We simulate quench dynamics between distinct Floquet topological phases using quantum-walk dynamics and experimentally characterize DQPTs and the underlying DTOPs through interference-based measurements. The versatile photonic quantum-walk platform further allows us to experimentally investigate DQPTs for mixed states and in parity-time-symmetric nonunitary dynamics for the first time. Our experiment directly confirms the relation between DQPTs and DTOPs in quench dynamics of topological systems and opens up the avenue of simulating emergent topological phenomena using discrete-time quantum-walk dynamics.
受物理可观测量的时间演化中非解析性的驱动，动态量子相变 (DQPT) 出现在拓扑系统的淬火动力学中，并且具有由动态拓扑序参量 (DTOP) 捕获的有趣的几何起源。在这篇快报中，我们使用单光子的离散时间量子行走来报告 DQPT 的实验研究。我们使用量子行走动力学模拟不同弗洛奎拓扑相之间的淬火动力学，并通过基于干涉的测量实验表征 DQPT 和潜在的 DTOP。多功能光子量子行走平台还使我们能够首次在混合态和宇称时间对称非幺正动力学中实验研究 DQPT。我们的实验直接证实了拓扑系统淬火动力学中 DQPT 和 DTOP 之间的关系，并为使用离散时间量子行走动力学模拟新兴拓扑现象开辟了道路。
