The time crystal was proposed in 2012, and got a lot of attentions and disscussions. In 2017, discrete time crystal, which appeared in Floquet driving systems, was realized in time crystal. In this talk, I discuss the concept of time crystal and discrete time crystal, and briefly summarized our proposal of space-time crystal and time quasi-crystal in trapped ions systems. Inspired by this proposal, we find that the nearly spontaneous dynamics appears near the ground state of Lipkin-Meshkov-Glick (LMG) model with a finite number of spins. We link this phenomena to quantum time crystal and time quasicrystal. Finally, we propose a scheme to realize an effective classical time crystal in an optically levitated charged nanoparticle under a modest magnetic field. The Hamiltonian of the system is solved, and we find that the time crystal phenomena can appear near the ground state. The experimental feasibility is briefly discussed.
2019-10-08 (周二) 10:00