标题： 次谐波自旋关联和弗洛凯时间晶体中的谱配对 显示英文标题

标题： Subharmonic spin correlations and spectral pairing in Floquet time crystals

摘要： 弗洛凯时间晶体的特点是时间关联函数的次谐波行为。 研究基于无序弗洛凯量子伊辛模型的典型时间晶体，我们表明其时间自旋关联直接与光谱特性相关，这种关系为有限链的关联函数提供了解析表达式，与数值模拟结果相比具有优势。 具体来说，我们表明平均无序的时间自旋关联与弗洛凯算符的本征值对的分裂分布的傅里叶变换成正比，这种分布与链长度呈指数精度的$\pi$差异。 我们发现分裂可以用对数正态分布很好地描述，这意味着时间自旋关联由两个参数表征。 我们讨论了这对弗洛凯时间晶体相图可能的影响。 显示英文摘要

摘要： Floquet time crystals are characterized by subharmonic behavior of temporal correlation functions. Studying the paradigmatic time crystal based on the disordered Floquet quantum Ising model, we show that its temporal spin correlations are directly related to spectral characteristics and that this relation provides analytical expressions for the correlation function of finite chains, which compare favorably with numerical simulations. Specifically, we show that the disorder-averaged temporal spin correlations are proportional to the Fourier transform of the splitting distribution of the pairs of eigenvalues of the Floquet operator, which differ by $\pi$ to exponential accuracy in the chain length. We find that the splittings are well described by a log-normal distribution, implying that the temporal spin correlations are characterized by two parameters. We discuss possible implications for the phase diagram of the Floquet time crystals.