论文标题
在耗散性中心自旋系统中的可稳定离散时晶共振
Metastable discrete time-crystal resonances in a dissipative central spin system
论文作者
论文摘要
我们考虑了中央自旋系统的非平衡行为，其中中心自旋定期重置为基态。在这种有效耗散动力学下的量子机械演化由离散时间量子图描述。尽管它很简单，但这个问题显示出令人惊讶的复杂动力学特征。特别是，我们确定了几种亚稳定的时晶共鸣。在这里，该系统不会迅速放松到固定状态，而是经历了长期的振荡，这是重置时期的整数倍数。在这些共振下，进化仅限于系统进行周期性运动的低维状态空间。在开放量子系统中概括了亚稳定性的理论，我们为这个长期寿命的亚稳态子空间中的演变开发了一个有效的描述，并表明在长期限制中，接近了非平衡固定状态。我们的研究与及时的问题联系在一起，即在耗散量子多体演化的“ prethermal”阶段中出现的集体行为，并可能建立与量子同步现象的有趣联系。
We consider the non-equilibrium behavior of a central spin system where the central spin is periodically reset to its ground state. The quantum mechanical evolution under this effectively dissipative dynamics is described by a discrete-time quantum map. Despite its simplicity this problem shows surprisingly complex dynamical features. In particular, we identify several metastable time-crystal resonances. Here the system does not relax rapidly to a stationary state but undergoes long-lived oscillations with a period that is an integer multiple of the reset period. At these resonances the evolution becomes restricted to a low-dimensional state space within which the system undergoes a periodic motion. Generalizing the theory of metastability in open quantum systems, we develop an effective description for the evolution within this long-lived metastable subspace and show that in the long-time limit a non-equilibrium stationary state is approached. Our study links to timely questions concerning emergent collective behavior in the 'prethermal' stage of a dissipative quantum many-body evolution and may establish an intriguing link to the phenomenon of quantum synchronization.
