Synthetic Gauge Potentials in Spinor Quantum Gases

In recent years, extensive interest has been drawn to a specific direction in the study of ultracold atoms—creating synthetic gauge potentials and gauge fields in an ultracold atomic ensemble. On the one hand, the creation of synthetic gauge potentials enables us to realize spin-orbit coupling, the quantum Hall effect, and the spin-Hall effect, which enable us to explore novel physics in a well-controlled, many-body system with tunable interactions that are hard to realize in other systems.

In our group, we explore creating synthetic gauge potentials in spinor quantum gases via a stimulated Raman process. Combining Floquet engineering with the Raman process, we can create artificial gauge potentials in both real space and parameter space. In one of our works, we have shown that the synthetic gauge potential in real space induces an optical lattice, where the lattice potential along the longitudinal direction is determined by the transverse momentum of the atoms. With this feature, one can tune the many-body phase in the lattice by changing the momentum state of the quantum gas in the transverse direction. 

In another work, we proposed using an artificial gauge potential in parameter space to generate a non-Abelian geometric phase in a dilute pseudo-spin-1/2 Bose gas. Using numerical simulations, we showed that the non-Abelian geometric phase is robust against parameter fluctuations, and thus has the potential to be used as another method of quantum control in a quantum gaseous system.

One interesting future direction would be to combine the synthetic gauge potential in real space with topologically structured Raman beams, and study both the single particle and many-body effects such a topologically non-trivial system. Another direction would be to explore the non-Abelian geometric phase in a higher spin system. Also, we plan to implement the experimental protocol we proposed on our new experimental platform in the near future.