Multifractality without fine-tuning in a Floquet quasiperiodic chain.
Multifractality without fine-tuning in a Floquet quasiperiodic chain.
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DOI：
10.21468/scipostphys.4.5.025
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发表时间：
2017-06
期刊：
影响因子：
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通讯作者：
S. Roy;Ivan M Khaymovich;Arnab Das;R. Moessner
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文献类型：
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作者：
S. Roy;Ivan M Khaymovich;Arnab Das;R. Moessner
最近，周期性驱动的无序量子系统产生了许多意想不到的发现，例如反常的弗洛奎特·安德森绝缘体和离散时间晶体。在这里，我们报告了在周期性驱动的非相互作用粒子链中出现了一整条多重分形波函数带，这些粒子受到空间准周期无序的影响。值得注意的是，这种多重分形性是稳健的，因为它不需要对模型参数进行任何微调，这使它有别于已知的$Critical$波函数的多重分形性。当周期性驱动使非驱动频谱的局域和非局域区段混合时，多重分形性就出现了。我们用一个简单的随机矩阵理论解释了这一现象。最后，我们讨论了多重分形态的动力学特征，这些特征揭示了它们在冷原子实验中的存在。这种对多重分形性的简单而强大的认识可能会将这一迄今难以捉摸的现象推向应用，例如所提出的无序诱导的超流体相变增强。
Periodically driven, or Floquet, disordered quantum systems have generated many unexpected discoveries of late, such as the anomalous Floquet Anderson insulator and the discrete time crystal. Here, we report the emergence of an entire band of multifractal wavefunctions in a periodically driven chain of non-interacting particles subject to spatially quasiperiodic disorder. Remarkably, this multifractality is robust in that it does not require any fine-tuning of the model parameters, which sets it apart from the known multifractality of $critical$ wavefunctions. The multifractality arises as the periodic drive hybridises the localised and delocalised sectors of the undriven spectrum. We account for this phenomenon in a simple random matrix based theory. Finally, we discuss dynamical signatures of the multifractal states, which should betray their presence in cold atom experiments. Such a simple yet robust realisation of multifractality could advance this so far elusive phenomenon towards applications, such as the proposed disorder-induced enhancement of a superfluid transition.