标题： 耗散量子相变的电流涨落监测 显示英文标题

标题： Dissipative quantum phase transitions monitored by current fluctuations

摘要： 耗散相变（DPT）由非平衡开放量子系统的物理性质的突然变化定义，并表现出封闭和热系统中没有类比的特点。 文献中提出了几种检测和表征DPT的方法，其中最著名的方法之一——$\textit{Liouvillian gap}$——可以从控制相干动力学与耗散动力学复杂相互作用的Liouvillian超算符的谱分析中推导出来。 在这里，我们考虑$\textit{output current}$，即开放量子系统与环境之间单位时间内平均总量子跃迁数。 我们提出，输出电流涨落，特别是它们的动力学关联性、功率谱及其特征时间尺度，可以为DPT提供有价值的信息，在临界点处确认行为的显著变化。 我们通过耗散XYZ模型和非线性驱动耗散Kerr模型验证了我们的提议，结果显示与之前关于临界点位置估计的良好一致性。 与先前的方法相比，我们的提议已经在光学系统中可以进行实验测试，提供了一种检测量子开放系统临界性的实用方法。 显示英文摘要

摘要： Dissipative phase transitions (DPT) are defined by sudden changes in the physical properties of nonequilibrium open quantum systems and they present characteristics that have no analogue in closed and thermal systems. Several methods to detect and characterize DPT have been suggested in the literature, the most famous of which -- the $\textit{Liouvillian gap}$ -- can be derived from a spectral analysis of the Liouvillian super-operator that governs the complex interplay between coherent and dissipative dynamics. Here, we consider the $\textit{output current}$, defined as the average total quantum jumps per unit time between the open quantum system and the environment. We propose that output current fluctuations, and in particular their dynamical correlations, their power spectrum, and their characteristic timescale can provide valuable information about DPT, confirming a dramatic change of behavior at the critical point. We validate our proposal using the dissipative XYZ model and the nonlinear driven-dissipative Kerr model, showing good agreement with previous estimates of the location of the critical point. Compared to previous approaches, our proposal could be already experimentally tested in optical systems, providing a practical method to detect criticality in quantum open systems.