Exact multistability and dissipative time crystals in interacting fermionic lattices
Exact multistability and dissipative time crystals in interacting fermionic lattices
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DOI：
10.1038/s42005-022-01090-z
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发表时间：
2022-12
影响因子：
5.5
通讯作者：
H. Alaeian;B. Buča
中科院分区：
文献类型：
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作者：
H. Alaeian;B. Buča
超越平均场近似的量子系统中是否存在多稳态仍然是一个有激烈争论的公开问题。量子涨落是对平均场的有限尺寸修正，因为完全精确解是不可获得的，并且它们通常破坏平均场水平上存在的多稳态。在这里，通过识别和使用确切的调制动力学对称性的驱动耗散费米子链，我们确切地证明了多稳定性的量子涨落的存在。此外，与我们模型中的常见情况不同，量子涨落本身并没有破坏多稳性，而是表现出多稳性，这在我们系统的平均场水平上是不存在的。此外，所研究的模型获得额外的热力学动力学对称性，这意味着持续的周期性振荡，构成边界时间晶体的第一种情况下，据我们所知，一个真正的扩展多体量子系统与以前的情况下，只有在紧急单或少体模型。在大耗散的极限下，该模型可以被制成耗散时间晶体（即持续振荡被耗散稳定），使其既是边界时间晶体又是耗散时间晶体。
The existence of multistability in quantum systems beyond the mean-field approximation remains an intensely debated open question. Quantum fluctuations are finite-size corrections to the mean-field as the full exact solution is unobtainable and they usually destroy the multistability present on the mean-field level. Here, by identifying and using exact modulated dynamical symmetries in a driven-dissipative fermionic chain we exactly prove multistability in the presence of quantum fluctuations. Further, unlike common cases in our model, rather than destroying multistability, the quantum fluctuations themselves exhibit multistability, which is absent on the mean-field level for our systems. Moreover, the studied model acquires additional thermodynamic dynamical symmetries that imply persistent periodic oscillations, constituting the first case of a boundary time crystal,to the best of our knowledge, a genuine extended many-body quantum system with the previous cases being only in emergent single- or few-body models. The model can be made into a dissipative time crystal in the limit of large dissipation (i.e. the persistent oscillations are stabilized by the dissipation) making it both a boundary and dissipative time crystal.