有限温度下量子保真度中体现的量子相变特征
Signature of quantum phase transition manifested in quantum fidelity at finite temperature
AI总结：
本文基于量子保真度构造速率函数，研究其在有限温度乃至高温下通过非解析行为表征量子相变的能力，并证明其长时极限可探测平衡态量子相变。
摘要：
量子相变的特征通常在有限温度下会被抹去。少数已被观测到通过非解析行为保留这一特征的物理量也仅限于低温区域。为了在高温下识别一个合适的动力学量，我们最近从量子保真度构造了一个函数，该函数有可能在超越低温区域的量子临界点处带有非解析特征。在本文中，我们详细阐述了我们早期的工作，并针对不同维度中的若干多体哈密顿量展示了相应速率函数的行为以及非解析性的鲁棒性。我们还证明了我们的速率函数可以约化为在零温下演示动力学量子相变（DQPT）时所使用的速率函数。进一步观察到，与DQPT不同，该速率函数的长时极限也能忠实地探测平衡态量子相变。
英文摘要：
The signature of quantum phase transition is generally wiped out at finite temperature. A few quantities that have been observed to carry this signature through a nonanalytic behavior are also limited to low temperatures only. With an aim to identify a suitable dynamical quantity at a high temperature, we have recently constructed a function from quantum fidelity, which has the potential to bear a nonanalytic signature at the quantum critical point beyond low temperature regime. In this paper, we elaborate our earlier work and demonstrate the behavior of the corresponding rate function and the robustness of the nonanalyticity for a number of many-body Hamiltonians in different dimensions. We have also shown that our rate function reduces to that used in the demonstration of the dynamical quantum phase transition (DQPT) at zero temperature. It has been further observed that, unlike DQPT, the long time limit of the rate function can faithfully detect the equilibrium quantum phase transition as well.
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