报告时间：6月7日 周三 下午3:00
报告题目：Non-Equilibrium Topological Insulators with Ultracold Atoms
There are presently ongoing experiments aimed at observing quantum Hall physics with ultracold gases. At zero temperature, the direct correspondence between the Chern number of the ground state, the Hall conductance, and the chiral edge states is well established. Yet, non-equilibrium scenarios generically occur in cold-atom experiments, where starting from a topologically trivial initial state, the Hamiltonian is parametrically driven into a topological regime. However, the system can never enter a Chern insulator state under such coherent evolution, thus raising the challenge as to which manifestations of topology can be actually observed in cold atom setups. Addressing this experiment relevant issue, we show that the non-equilibrium Hall response can be quantized despite the non-topological nature of the state at all times . I will proceed to discuss how Floquet driving can be harnessed to transcend fundamental constraints in equilibrium systems. Specifically, I show that the perfect spin momentum locking, which in equilibrium only occurs in 2D topological insulators, can emerge in 1D Floquet lattice systems non-adiabatically .
. Ying Hu, Peter Zoller, Jan Carl Budich, Dynamical Buildup of a Quantized Hall Response from Non-Topological States, Phys. Rev. Lett. 117, 126803 (2016)
. Jan Carl Budich, Ying Hu, Peter Zoller, Helical Floquet Channels in 1D Lattices, Phys. Rev. Lett. 118.105302 (2017)