标题： 拟 dressed 量子轨迹：一种在广泛时间尺度上研究开放量子系统非马尔可夫动力学的新方法 显示英文标题

标题： Dressed Quantum Trajectories: Novel Approach to the non-Markovian Dynamics of Open Quantum Systems on a Wide Time Scale

摘要： 一种新的方法用于开放量子系统的非马尔可夫动力学的理论和模拟。它基于识别一个在宽时间间隔上始终很小的参数：虚拟云的激发数。我们用“虚拟”来表示那些由系统发射但最终会在任何浴态测量之前被重新吸收的浴激发。虚拟云的一个有利特性是，其激发数在长时间内预计会趋于饱和，因为从物理上看，这个云是系统周围浴的（滞后）极化。因此，在广泛的时标上，开放系统和虚拟云的联合状态（即“穿衣态”）可以准确地用福克态截断基来表示。同时，可观测激发数可能很大，特别是当开放系统受到驱动时。然而，通过采用对浴测量结果的蒙特卡洛采样，我们可以模拟可观测量子场的动力学。在本工作中，我们考虑相对于相干态的测量，这给出了赫斯米函数作为结果的正（准）概率分布。对应于特定固定结果的穿衣态的演化称为穿衣量子轨迹。因此，这些轨迹的蒙特卡洛采样产生了一种在广泛时间尺度上具有良好收敛性质的随机模拟方法。 显示英文摘要

摘要： A new approach to the theory and simulation of the non-Markovian dynamics of open quantum systems is presented. It is based on identification of a parameter which is uniformly small on wide time intervals: the occupation of the virtual cloud of quanta. By "virtual" we denote those bath excitations which were emitted by the system, but eventually will be reabsorbed before any measurement of the bath state. A favourable property of the virtual cloud is that the number of its quanta is expected to saturate on long times, since physically this cloud is a (retarded) polarization of the bath around the system. Therefore, the joint state of open system and of virtual cloud (the dressed state) can be accurately represented in a truncated basis of Fock states, on a wide time scale. At the same time, there can be arbitrarily large number of observable quanta, especially if the open system is under driving. However, by employing a Monte Carlo sampling of the measurement outcomes of the bath, we can simulate the dynamics of the observable quantum field. In this work we consider the measurement with respect to the coherent states, which yields the Husimi function as the positive (quasi)probability distribution of the outcomes. The evolution of dressed state which corresponds to a particular fixed outcome is called the dressed qauntum trajectory. Therefore, the Monte Carlo sampling of these trajectories yields a stochastic simulation method with promising convergence properties on wide time scales.