论文标题
在连续测量下，自由铁气体的Keldysh非线性Sigma模型
Keldysh Nonlinear Sigma Model for a Free-Fermion Gas under Continuous Measurements
论文作者
论文摘要
量子纠缠相变为量子多体动力学提供了新的见解。发现疾病和测量值都引起了类似的纠缠转变。在这里，我们提供了一个理论框架，该框架统一了这两个看似不同的概念并披露了它们的内部联系。具体而言，我们通过分析分析了$ d $ dimension的自由阵容气体，但要经过持续的投影测量。通过将lindblad主方程映射到功能性的Keldysh场理论，我们开发了一种有效的理论，该理论称为时间本地Keldysh非线性Sigma模型，使我们能够分析监测系统的物理学。我们的有效理论类似于用来描述无序的费米子体系的理论。作为有效理论的应用，我们研究了运输特性，并获得了弹性散射时间被反向测量强度取代的腐蚀形式的电导率。根据这些相似之处，在相同的理论框架中统一了两个不同的概念，测量和疾病。还提供了我们理论和预测的数值验证。
Quantum entanglement phase transitions have provided new insights to quantum many-body dynamics. Both disorders and measurements are found to induce similar entanglement transitions. Here, we provide a theoretical framework that unifies these two seemingly disparate concepts and discloses their internal connections. Specifically, we analytically analyze a $d$-dimension free-fermion gas subject to continuous projective measurements. By mapping the Lindblad master equation to the functional Keldysh field theory, we develop an effective theory termed as the time-local Keldysh nonlinear sigma model, which enables us to analytically describe the physics of the monitored system. Our effective theory resembles to that used to describe the disordered fermionic systems. As an application of the effective theory, we study the transport property and obtain a Drude-form conductivity where the elastic scattering time is replaced by the inverse measurement strength. According to these similarities, two different concepts, measurements and disorders, are unified in the same theoretical framework. A numerical verification of our theory and predictions is also provided.
