利用静态量子多体疤痕产生倍周期响应
Leveraging static quantum many-body scars into period-doubled responses
AI总结：
本文提出利用静态量子多体疤痕哈密顿量中的 su(2) 谱生成代数，通过周期性驱动在疤痕子空间内实现 π 旋转，从而产生倍周期响应，并在多种自旋模型及近似对称 PXP 模型中验证了该方案，扩展了可产生时间晶体行为的量子疤痕模型类别。
摘要：
我们提出了一种方案，通过周期性驱动某些承载量子多体疤痕的哈密顿量来产生倍周期响应，类似于近期在驱动里德伯原子阵列中的实验观测。我们的构造利用了一个与静态量子疤痕哈密顿量相关的 su(2) 谱生成代数，在适当选择驱动参数的情况下，经过一个周期的时间演化后，该代数在疤痕子空间内实现一个 $π$ 旋转。这使得对于任何位于疤痕子空间中的初始态，局域观测量都会产生倍周期（次谐波）响应。准能谱具有嵌入在原本完全热化谱中的非典型 $π$ 配对本征态。该协议既不需要大的驱动频率，也不需要大的驱动幅度，因此不同于以往对驱动 PXP 模型的预热化物理研究。我们使用几个具有精确 su(2) 谱生成代数的自旋-1/2 和自旋-1 量子疤痕模型，以及一个 su(2) 代数仅为近似的对称性变形 PXP 模型来演示我们的方案。我们的结果扩展了承载量子多体疤痕的模型类别，这些模型可以被利用来在周期性驱动下产生时间晶体行为。
英文摘要：
We propose a scheme that generates period-doubled responses via periodically driving certain Hamiltonians hosting quantum many-body scars, akin to recent experimental observations in driven Rydberg atom arrays. Our construction takes advantage of an su(2) spectrum generating algebra associated with the static quantum-scarred Hamiltonian, which enacts a $π$-rotation within the scar subspace after one period of time evolution with appropriately chosen driving parameters. This yields period-doubled (subharmonic) responses in local observables for any choice of initial state residing in the scar subspace. The quasienergy spectrum features atypical $π$-paired eigenstates embedded in an otherwise fully thermal spectrum.The protocol requires neither a large driving frequency nor a large driving amplitude, and is thus distinct from the prethermalization physics in previous investigations of the driven PXP model. We demonstrate our scheme using several spin-1/2 and spin-1 quantum scarred models possessing an exact su(2) spectrum generating algebra, as well as a symmetry-deformed PXP model, where the su(2) algebra is only approximate. Our results extend the class of models hosting quantum many-body scars that can be leveraged to yield time-crystalline behaviors under periodic driving.
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