Simulating chiral phenomena with ultracold atomic gases: from s-band to p-band, from real-space to momentum-space(2019.10.24, 5:00 pm)

报告题目:Simulating chiral phenomena with ultracold atomic gases: from s-band to p-band, from real-space to momentum-space

报告人:李永强 副教授(国防科技大学)



摘要:The interplay of spin, orbital, and charge degrees of freedom is one of the cornerstones of correlated quantum materials. Many intriguing quantum phases of electronic matter can be attributed to higher order electronic orbitals and spin-orbital interactions, e.g., in exotic superconductivity in pnictides and strontium ruthenates, as well as in various topological insulators and Weyl semimetals. In this talk, we mainly focus on two issues:                  

First, we propose a mechanism of spontaneous generation of spin angular-momentum coupling with spinor atomic bosons loaded into p-orbital bands of a two-dimensional optical-lattice. This spin angular momentum coupling originates from many-body correlations and spontaneous symmetry breaking in a superfluid, with the key ingredients attributed to spin-channel quantum fluctuations and an approximate rotation symmetry. The resultant spin angular-momentum intertwined superfluid has Dirac excitations.                  

Second, we propose to study the many-body chiral edge current of ultracold gases in a momentum-space superradiance lattice by coupling with a Rydberg state. We explore stationary and dynamical properties of the momentum-space lattice in an artificial magnetic field. The many-body ground states support both chiral and anti-chiral edge currents in momentum space. Their stability against strong interactions is verified by a dynamical mean-field simulation. We show that the interplay of the interaction and chirality leads to correlated chiral dynamics, where an interaction-induced excitation blockade in momentum space suppresses the edge currents. When incorporating an effective decay to the lattice, we find that excitation transportation, whose dynamics is governed by a dissipative Bose-Hubard model, can be prohibited by a strong local dissipation, as a result of the quantum Zeno effect.