近日，印度科学教育与研究所的Victor Mukherjee及其研究团队取得一项新进展。经过不懈努力，他们对存在非马尔可夫动力学的离散时间晶体进行研究。相关研究成果已于2024年7月10日在国际知名学术期刊《物理评论A》上发表。

该研究团队研究了周期驱动量子系统中存在非马尔可夫耗散的离散时间晶体（DTCs）。与早期工作中观察到的存在马尔可夫动力学的DTCs相反，研究人员使用存在类Jaynes-Cummings耗散的开放迪克模型，表明非马尔可夫状态对于在大范围参数值上稳定DTCs非常有益。这可能是由于在非马尔可夫动力学的情况下，即使在很长时间内耗散率也会周期性变化。

此外，马尔可夫和非马尔可夫状态在耗散系数的中间强度方面表现出明显的区别，在马尔可夫状态中，与时间无关的稳态被非马尔可夫状态中的各种动态相位(包括DTC序)所取代。研究人员还通过引入哈密顿量和耗散的误差，来验证DTC相位在非马尔可夫状态下的鲁棒性。这项研究表明，在长时间内，使用DTC作为周期调制开放量子系统中非马尔可夫动力学的探针是可能的。

附：英文原文

Title: Discrete time crystals in the presence of non-Markovian dynamics

Author: Bandita Das, Noufal Jaseem, Victor Mukherjee

Issue&Volume: 2024/07/10

Abstract: We study discrete time crystals (DTCs) in periodically driven quantum systems, in the presence of non-Markovian dissipation. In contrast to DTCs observed in earlier works in the presence of Markovian dynamics, using the open Dicke model in presence of Jaynes-Cummings-like dissipation, we show that non-Markovian regime can be highly beneficial for stabilizing DTCs over a wide range of parameter values. This may be attributed to periodically varying dissipation rates even at long times in the case of non-Markovian dynamics. Further the Markovian and non-Markovian regimes show sharp distinctions for intermediate strengths of the dissipator coefficient, with a time-independent steady state in the Markovian regime being replaced by varied dynamical phases, including DTC order, in the non-Markovian regime. We also verify the robustness of the DTC phase in the non-Markovian regime by introducing errors both in the Hamiltonian as well as in the dissipation. Our study shows the possibility of using DTC as a probe for non-Markovian dynamics in periodically modulated open quantum systems, at long times.

DOI: 10.1103/PhysRevA.110.012208

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.012208