Stability of the Discrete Time-Crystalline Order in Spin-Optomechanical and Open Cavity QED Systems
Stability of the Discrete Time-Crystalline Order in Spin-Optomechanical and Open Cavity QED Systems
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DOI：
10.3390/photonics9020061
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发表时间：
2022-01
期刊：
影响因子：
2.4
通讯作者：
Zhengda Hu;Xingyu Gao;Tongcang Li
中科院分区：
文献类型：
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作者：
Zhengda Hu;Xingyu Gao;Tongcang Li
在过去的几年中，离散时间晶体（DTC）已经在几个不同的量子系统中得到了实验证明。自旋耦合和腔损失在非平衡开放多体系统中实现DTC有序中起着至关重要的作用。近年来，人们提出了在热力学极限和少量量子位元的深度量子状态下，永恒和瞬态DTC可以分别以开放的Floquet设置存在。在这项工作中，我们考虑了自旋阻尼和自旋减相对自旋光力学和开放腔系统中自旋可以全对全耦合的DTC顺序的影响。在热力学极限下，证明了消相的存在会破坏系统的相干性，最终导致系统达到平凡的稳态。在没有消相的情况下，永久DTC表现为弱阻尼状态，可以通过增加全对全自旋耦合或自旋阻尼来破坏。相反，在中等阻尼状态下，全对全耦合对DTC是建设性的。我们还重点研究了在微波驱动和Floquet磁场作用下，用带有几个自旋色中心的悬浮六方氮化硼（hBN）膜实验实现的模型。在无自旋消相的弱耗散和中等耗散状态下，证明了瞬态DTC行为的特征。讨论了在这种hBN光机械系统中实现瞬态DTC有序的相关实验参数。
Discrete time crystals (DTC) have been demonstrated experimentally in several different quantum systems in the past few years. Spin couplings and cavity losses have been shown to play crucial roles for realizing DTC order in open many-body systems out of equilibrium. Recently, it has been proposed that eternal and transient DTC can be present with an open Floquet setup in the thermodynamic limit and in the deep quantum regime with few qubits, respectively. In this work, we consider the effects of spin damping and spin dephasing on the DTC order in spin-optomechanical and open cavity systems in which the spins can be all-to-all coupled. In the thermodynamic limit, it is shown that the existence of dephasing can destroy the coherence of the system and finally lead the system to its trivial steady state. Without dephasing, eternal DTC is displayed in the weak damping regime, which may be destroyed by increasing the all-to-all spin coupling or the spin damping. By contrast, the all-to-all coupling is constructive to the DTC in the moderate damping regime. We also focus on a model which can be experimentally realized by a suspended hexagonal boron nitride (hBN) membrane with a few spin color centers under microwave drive and Floquet magnetic field. Signatures of transient DTC behavior are demonstrated in both weak and moderate dissipation regimes without spin dephasing. Relevant experimental parameters are also discussed for realizing transient DTC order in such an hBN optomechanical system.