标题： 通过虚时间演化确定量子轨迹 显示英文标题

标题： Deterministic quantum trajectory via imaginary time evolution

摘要： 随机量子轨迹，例如在幺正动力学下的纯态演化和随机测量，为多体开放系统动力学提供了关键的系综描述。近期的研究表明，单个量子轨迹也编码了重要的物理信息。突出的例子包括测量诱导的相变，在这种相变中，对应于固定测量结果（轨迹）的纯量子态表现出不同的纠缠相位，这取决于测量速率。然而，由于指数级后选择障碍的存在，直接观测这一效应受到阻碍，因为实现特定轨迹的概率呈指数级下降。我们提出了一种确定性方法，利用虚时间演化在多项式时间内高效制备量子轨迹，从而克服这一根本性的挑战。我们证明了该方法适用于一类量子态，并且认为不存在适用于任意量子轨迹的通用方法。我们的研究为大规模实验探索单个量子轨迹的物理特性铺平了道路，并使某些后选择依赖现象的直接观测成为可能。 显示英文摘要

摘要： Stochastic quantum trajectories, such as pure state evolutions under unitary dynamics and random measurements, offer a crucial ensemble description of many-body open system dynamics. Recent studies have highlighted that individual quantum trajectories also encode essential physical information. Prominent examples include measurement induced phase transitions, where a pure quantum state corresponding to fixed measurement outcomes (trajectories) exhibits distinct entanglement phases, depending on the measurement rate. However, direct observation of this effect is hindered by an exponential post-selection barrier, whereby the probability of realizing a specific trajectory is exponentially small. We propose a deterministic method to efficiently prepare quantum trajectories in polynomial time using imaginary time evolution and, thus, overcome this fundamental challenge. We demonstrate that our method applies to a certain class of quantum states, and argue that there does not exist universal approaches for any quantum trajectories. Our result paves the way for experimentally exploring the physics of individual quantum trajectories at scale and enables direct observation of certain post-selection-dependent phenomena.