论文标题
定期驱动的系统中出色的动态量子相变
Exceptional Dynamical Quantum Phase Transitions in Periodically Driven Systems
论文作者
论文摘要
扩展到非平衡领域的相变概念是统计力学的基本问题。虽然发现即使是在放松之前作为瞬态状态作为动态自由能的奇异性发生的临界过渡，但它们的性质尚未难以捉摸。在这里，我们表明自发对称性破裂可能会在短时间内发生，并在定期驱动的统一动力学中引起通用动力学量子相变。与常规的相变不同，相关的对称性是反对的：它的破裂伴随着由时空二元性获得的单身非独特算子的多体特殊点。使用频镜统一模型，我们证明了动态自由能的不同阶段和非常规奇异性的存在，它们的签名可以通过准局部运算符访问。我们的结果在短期制度中为迄今未知阶段开辟了研究，在短时间内，时间是另一个关键参数，并与他们与非整体物理学的隐藏联系。
Extending notions of phase transitions to nonequilibrium realm is a fundamental problem for statistical mechanics. While it was discovered that critical transitions occur even for transient states before relaxation as the singularity of a dynamical version of free energy, their nature is yet to be elusive. Here, we show that spontaneous symmetry breaking can occur at a short-time regime and causes universal dynamical quantum phase transitions in periodically driven unitary dynamics. Unlike conventional phase transitions, the relevant symmetry is antiunitary: its breaking is accompanied by a many-body exceptional point of a nonunitary operator obtained by space-time duality. Using a stroboscopic Ising model, we demonstrate the existence of distinct phases and unconventional singularity of dynamical free energy, whose signature can be accessed through quasilocal operators. Our results open up research for hitherto unknown phases in short-time regimes, where time serves as another pivotal parameter, with their hidden connection to nonunitary physics.
