Floquet prethermalization in dipolar spin chains
Floquet prethermalization in dipolar spin chains
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DOI：
10.1038/s41567-020-01120-z
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发表时间：
2021-01
期刊：
影响因子：
19.6
通讯作者：
Pai Peng;Chao Yin;Xiaoyang Huang;C. Ramanathan;P. Cappellaro
中科院分区：
文献类型：
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作者：
Pai Peng;Chao Yin;Xiaoyang Huang;C. Ramanathan;P. Cappellaro
周期性驱动的Floquet量子系统可以提供一个很有前途的平台来研究新的平衡物理，但驱动器通常会将系统加热到一个无特征的无限温度状态。幸运的是，对于高驱动频率，热吸收率在理论上被预测为指数小，从而产生长寿命的预热状态，其表现出Floquet系统的所有有趣的特性。在这里，我们实验观察Floquet预热化使用NMR技术和探测的加热速率。首先，我们展示了一个远离平衡的初始状态，以及描述了一个时间无关的“prethermal”哈密顿量的一个长寿的prethermal状态的松弛。通过测量这个预热哈密顿量的自相关性，我们可以进一步实验证实预测的指数缓慢加热速率。更引人注目的是，我们发现，在时间尺度上的预热哈密顿图像崩溃，Floquet系统仍然拥有其他的准一致性法律。我们的研究结果表明，它是可能实现强大的Floquet工程，从而使非平凡的Floquet相位的物质的实验观察。
Periodically driven Floquet quantum systems could provide a promising platform to investigate novel physics out of equilibrium, but the drive generically heats the system to a featureless infinite-temperature state, –. Fortunately, for high driving frequency, the heat absorption rate has been theoretically predicted to be exponentially small, giving rise to a long-lived prethermal regime that exhibits all the intriguing properties of Floquet systems, , –. Here we experimentally observe Floquet prethermalization using NMR techniques and probe the heating rate. We first show the relaxation of a far-from-equilibrium initial state to a long-lived prethermal state, well described by a time-independent ‘prethermal’ Hamiltonian. By measuring the autocorrelation of this prethermal Hamiltonian we can further experimentally confirm the predicted exponentially slow heating rate. More strikingly, we find that, on the timescale at which the prethermal Hamiltonian picture breaks down, the Floquet system still possesses other quasiconservation laws. Our results demonstrate that it is possible to realize robust Floquet engineering, thus enabling the experimental observation of non-trivial Floquet phases of matter.