标题： 评论“单模非线性腔中的时间晶体” 显示英文标题

标题： Comment on "Time Crystal in a Single-mode Nonlinear Cavity"

摘要： 我主张，单个受驱动的量子范德波尔振子不应被视作耗散时间晶体，这与之前的主张相反。 特别是，我表明当考虑去相或额外的非线性时，其相位容易随机漂移，因此在这一点上其振荡并不稳健。 我提供的论点适用于文献中许多其他模型，这些模型的持续振荡极限与经典极限一致。 我希望这一评论能引发关于什么应或不应被视为时间晶体（至少在开放量子系统的背景下）的讨论，并将其澄清到一个明确的程度。 显示英文摘要

摘要： I argue that a single driven quantum Van der Pol oscillator should not be considered a dissipative time crystal, contrary to previous claims. In particular, I show that its phase is prone to randomly drift when considering dephasing or additional nonlinearities, and hence its oscillations are not robust in that sense. The arguments I provide are applicable to many other models studied in the literature for which the limit of persistent oscillations coincides with the classical limit. I hope that this comment will spark a discussion about what should or should not be considered a time crystal (at least in the context of open quantum systems) and clarify it to a point.