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arXiv 2207.04489quant-ph
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非谐 Lipkin-Meshkov-Glick 模型中的激发态量子相变:动力学方面

Excited-State Quantum Phase Transitions in the Anharmonic Lipkin-Meshkov-Glick Model: Dynamical Aspects

Jamil Khalouf-Rivera, Juan Gamito, Francisco Pérez-Bernal, José Miguel Arias, Pedro Pérez-Fernández

AI总结:

本文研究了非谐 LMG 模型中新产生的激发态量子相变(ESQPT)的动力学影响,通过量子淬火协议分析存活概率、局部态密度、Loschmidt 回波和 OTOC 的演化,发现其动力学后果与标准模型中的 ESQPT 相似。

摘要:

标准 Lipkin-Meshkov-Glick (LMG) 模型经历二阶基态量子相变 (QPT) 和激发态量子相变 (ESQPT)。在 LMG 哈密顿量中加入非谐项会产生第二个 ESQPT,从而改变模型的静态特性 [Phys. Rev. E 106, 044125 (2022)]。在本文中,分析了与这一新 ESQPT 相关的动力学影响。为此,在系统哈密顿量上定义了一个量子淬火协议,将初始状态(通常是基态)转变为随时间演化的复杂激发态。讨论了新 ESQPT 对量子淬火后存活概率和局部态密度的时间演化的影响,以及对 Loschmidt 回波和微正则乱序关联子 (OTOC) 的影响。非谐性诱导的 ESQPT 尽管物理起源不同,但其动力学后果与标准 LMG 模型中已有的 ESQPT 所观察到的相似。

英文摘要:

The standard Lipkin-Meshkov-Glick (LMG) model undergoes a second-order ground-state quantum phase transition (QPT) and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the LMG Hamiltonian gives rise to a second ESQPT that alters the static properties of the model [Phys. Rev. E 106, 044125 (2022)]. In the present work, the dynamical implications associated to this new ESQPT are analyzed. For that purpose, a quantum quench protocol is defined on the system Hamiltonian that takes an initial state, usually the ground state, into a complex excited state that evolves on time. The impact of the new ESQPT on the time evolution of the survival probability and the local density of states after the quantum quench, as well as on the Loschmidt echoes and the microcanonical out-of-time-order correlator (OTOC) are discussed. The anharmonity-induced ESQPT, despite having a different physical origin, has dynamical consequences similar to those observed in the ESQPT already present in the standard LMG model.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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