论文标题
评论“与长期相互作用的汉密尔顿人的量子时间晶体”
Comment on "Quantum Time Crystals from Hamiltonians with Long-Range Interactions"
论文作者
论文摘要
在最近的一篇论文（物理学修订版123，210602）中，Kozin和Kyriienko声称通过研究具有长期和无限体相互作用的模型来实现“真正的”基础状态晶体。在这里，我们指出他们的模型是双重问题的：他们是无法实现的$ {\ it and} $，他们违反了确定物质阶段的良好原则。确实，允许无限的身体操作员，几乎所有量子系统都是时间晶体。此外，他们的一个模型之一是高度不稳定的，另一种是通过微调在许多身体系统中隔离单个自由度 - 因此，这会提高伽利略和Huygens的摆升至真实的时代晶体。
In a recent paper (Phys. Rev. Lett. 123, 210602), Kozin and Kyriienko claim to realize "genuine" ground state time crystals by studying models with long-ranged and infinite-body interactions. Here we point out that their models are doubly problematic: they are unrealizable ${\it and}$ they violate well established principles for defining phases of matter. Indeed with infinite body operators allowed, almost all quantum systems are time crystals. In addition, one of their models is highly unstable and another amounts to isolating, via fine tuning, a single degree of freedom in a many body system--allowing for this elevates the pendulum of Galileo and Huygens to a genuine time crystal.
