He Guanghui, Ye Bingtian, Gong Ruotian, Liu Zhongyuan, Murch Kater W, Yao Norman Y, Zu Chong
Department of Physics, Washington University, St. Louis, Missouri 63130, USA.
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2023 Sep 29;131(13):130401. doi: 10.1103/PhysRevLett.131.130401.
Floquet (periodic) driving has recently emerged as a powerful technique for engineering quantum systems and realizing nonequilibrium phases of matter. A central challenge to stabilizing quantum phenomena in such systems is the need to prevent energy absorption from the driving field. Fortunately, when the frequency of the drive is significantly larger than the local energy scales of the many-body system, energy absorption is suppressed. The existence of this so-called prethermal regime depends sensitively on the range of interactions and the presence of multiple driving frequencies. Here, we report the observation of Floquet prethermalization in a strongly interacting dipolar spin ensemble in diamond, where the angular dependence of the dipolar coupling helps to mitigate the long-ranged nature of the interaction. Moreover, we extend our experimental observation to quasi-Floquet drives with multiple incommensurate frequencies. In contrast to a single-frequency drive, we find that the existence of prethermalization is extremely sensitive to the smoothness of the applied field. Our results open the door to stabilizing and characterizing nonequilibrium phenomena in quasiperiodically driven systems.
弗洛凯（周期性）驱动最近已成为一种用于工程量子系统和实现物质非平衡相的强大技术。在这类系统中稳定量子现象的一个核心挑战是需要防止从驱动场吸收能量。幸运的是，当驱动频率显著大于多体系统的局部能量尺度时，能量吸收会受到抑制。这种所谓的预热 regime 的存在敏感地取决于相互作用范围和多个驱动频率的存在。在这里，我们报告了在金刚石中强相互作用偶极自旋系综中弗洛凯预热化的观测结果，其中偶极耦合的角度依赖性有助于减轻相互作用的长程性质。此外，我们将实验观测扩展到具有多个不相称频率的准弗洛凯驱动。与单频驱动相比，我们发现预热化的存在对所施加场的平滑度极其敏感。我们的结果为在准周期驱动系统中稳定和表征非平衡现象打开了大门。
