论文标题
动力学量子相变的loschmidt振幅光谱
Loschmidt amplitude spectrum in dynamical quantum phase transitions
论文作者
论文摘要
动力学量子相变（DQPTS）是量子系统时间演变的关键，其存在是从理论上预测和实验观察到的。但是，系统在DQPT附近的行为及其与物理可观察物的联系仍然是一个悬而未决的问题。在这项工作中，我们介绍了Loschmidt振幅光谱（LAS）的概念，该振幅（LAS）扩展了Loscmidt振幅 - 过渡的探测器 - 通过考虑最初状态的重叠与前对汉密尔顿先前汉密尔顿的所有特征状态的重叠。通过分析可集成的横向场模型中的LA，我们发现该系统在跨DQPT的动量空间中经历了种群重新分布。在准粒子图片中，当系统处于DQPT时，所有下半部的K模式都会激发。 LAS还适用于研究不可融合模型的动力学，在该模型中，我们研究了以下新的邻居相互作用的Ising模型。发现系统磁化的时间演变已连接到LAS的产物，并且存在时间演化状态的同时重叠，与具有负磁化的旋转构型的prequnech hamiltonian的成对征收征。我们的发现可以更好地理解DQPT周围不平衡系统的特征。
Dynamical quantum phase transitions (DQPTs) are criticalities in the time evolution of quantum systems and their existence has been theoretically predicted and experimentally observed. However, how the system behaves in the vicinity of DQPT and its connection to physical observables remains an open question. In this work, we introduce the concept of the Loschmidt amplitude spectrum (LAS), which extends the Loscmidt amplitude - the detector of the transition - by considering the overlap of the initial state to all the eigenstates of the prequench Hamiltonian. By analysing the LAS in the integrable transverse-field Ising model, we find that the system undergoes a population redistribution in the momentum space across DQPT. In the quasiparticle picture, all the lower-half k modes are excited when the system is at DQPT. The LAS is also applicable to study the dynamics of non-integrable models where we have investigated the Ising model with next-nearest-neighbour interactions as an example. The time evolution of the system's magnetization is found to be connected to the products of the LAS and there exists a simultaneous overlap of the time-evolved state to pairs of eigenstates of the prequnech Hamiltonian that possess spin configurations of negative magnetization. Our findings provide a better understanding of the characteristics of the out-of-equilibrium system around DQPT.
