Ikeda Tatsuhiko N, Mori Takashi, Kaminishi Eriko, Ueda Masahito
Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev E. 2017 Feb;95(2-1):022129. doi: 10.1103/PhysRevE.95.022129. Epub 2017 Feb 22.
Entanglement prethermalization (EP) refers to a quasi-stationary nonequilibrium state of a composite system in which each individual subsystem looks thermal but the entire system remains nonthermal due to quantum entanglement between subsystems. We theoretically study the dynamics of EP following a coherent split of a one-dimensional harmonic potential in which two interacting bosons are confined. This problem is equivalent to that of an interaction quench between two harmonic oscillators. We show that this simple model captures the bare essentials of EP; that is, each subsystem relaxes to an approximate thermal equilibrium, whereas the total system remains entangled. We find that a generalized Gibbs ensemble exactly describes the total system if we take into account nonlocal conserved quantities that act nontrivially on both subsystems. In the presence of a symmetry-breaking perturbation, the relaxation dynamics of the system exhibits a quasi-stationary EP plateau and eventually reaches thermal equilibrium. We analytically show that the lifetime of EP is inversely proportional to the magnitude of the perturbation.
纠缠预热（EP）指的是复合系统的一种准稳态非平衡态，其中每个子系统看起来处于热态，但由于子系统之间的量子纠缠，整个系统仍处于非热态。我们从理论上研究了一维谐振势相干分裂后EP的动力学，其中两个相互作用的玻色子被限制在该势中。这个问题等同于两个谐振子之间的相互作用猝灭问题。我们表明，这个简单模型抓住了EP的基本要点；也就是说，每个子系统弛豫到近似热平衡，而整个系统仍保持纠缠。我们发现，如果考虑到对两个子系统都有非平凡作用的非局域守恒量，广义吉布斯系综能精确描述整个系统。在存在对称性破缺微扰的情况下，系统的弛豫动力学呈现出一个准稳态的EP平台，并最终达到热平衡。我们通过分析表明，EP的寿命与微扰幅度成反比。
