Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
Department of Physics, Technische Universität München, 85747 Garching, Germany.
Phys Rev Lett. 2019 Oct 11;123(15):150601. doi: 10.1103/PhysRevLett.123.150601.
We investigate the out-of-equilibrium properties of a system of interacting bosons in a ring lattice. We present a Floquet driving that induces clockwise (counterclockwise) circulation of the particles among the odd (even) sites of the ring which can be mapped to a fully connected model of clocks of two counterrotating species. The clocklike motion of the particles is at the core of a period-n discrete time crystal where L=2n is the number of lattice sites. In the presence of a "staircaselike" on-site potential, we report the emergence of a second characteristic timescale in addition to the period n-tupling. This new timescale depends on the microscopic parameters of the Hamiltonian and is incommensurate with the Floquet period, underpinning a dynamical phase we call "time quasicrystal." The rich dynamical phase diagram also features a thermal phase and an oscillatory phase, all of which we investigate and characterize. Our simple, yet rich model can be realized with state-of-the-art ultracold atoms experiments.
我们研究了在环形晶格中相互作用玻色子系统的非平衡性质。我们提出了一种 Floquet 驱动,它诱导粒子在环的奇数(偶数)站点之间顺时针(逆时针)循环,这可以映射到两个反向旋转物种的时钟的全连接模型。粒子的时钟样运动是周期为 n 的离散时间晶体的核心,其中 L=2n 是晶格站点的数量。在存在“阶梯状”局域势的情况下,除了 n 倍周期外,我们还报告了第二个特征时间尺度的出现。这个新的时间尺度取决于哈密顿量的微观参数,并且与 Floquet 周期不同步,这支持了我们称之为“时间准晶体”的动力学相。丰富的动力学相图还具有热相和振荡相,我们都对它们进行了研究和表征。我们的简单但丰富的模型可以用最先进的超冷原子实验来实现。