Quantum Optics Laboratory

Abstract:

Hysteresis is well known in magnetism, where the magnetization lags behind the driving magnetic field. Recently, hysteresis has been demonstrated in ultracold atoms by rotating a superfluid in a ring-shape potential. By exploiting a similar competition between external driving and dissipation, I will show that rate-dependent hysteresis of a normal Fermi gas can arise in a ring-shape trap. The area of hysteresis loop reveals the dissipated energy, and I will show a universal dependence of the area on the relaxation time in magnetic and ultracold-atom systems. By adding a periodic lattice potential to the ring-shape potential, the resulting superlattices for cold-atoms have brought opportunities for exploring topological properties. I will summarize how to characterize the topological invariant of a dimerized superlattice and its topological edge states. By generalizing the superlattice structure, I will show there are localized states protected by symmetry but not topology.