题 目：Two Component Bose Gases with Rashba Spin-orbit Coupling

报告人：余増强 博士 (University of Trento, Italy)

时 间：2014年1月8日（星期三）上午10:00

地 点：中心教学楼610

ABSTRACT

The experimental progress of spin-orbit (SO) coupled quantum gases have generated great interest recently. Unlike the SO coupling extensively studied in solid matter, the synthetic SO coupling in dilute cold atomic gases can be realized in feasible configurations with a tunable coupling strength. Moreover, it provides a unique platform to study the rich physics of SO effects in a bosonic system, which have not been explored before. One particular interesting configuration is Rashba SO coupling. In free space, since the minima of the single-particle spectrum have infinite degeneracy, the ground state of a Rashba SO coupled Bose gas is in fact determined by the details of interactions. In this talk, I will present my recent study on the phase diagram of this Rashba system. In addition to the plane-wave condensate and spin-density-wave condensate predicted in previous works, a ferromagnetic condensate phase is identified. This ferromagnetic phase competes with the spin density wave phase when interspecies interaction is stronger than intraspecies interaction, and the former one is always the ground state for weak enough spin-orbit coupling. When the energies of these two phases are close, there is a phase separation between them. At finite temperature, the ferromagnetic order could emerge in the normal state without Bose condensation. The spontaneous spin polarization removes the degeneracy of quasiparticles' energy minima, and consequently the modified density-of-state accommodates a condensate to appear below a critical temperature. [ Reference: Phys. Rev. A 87, 051606(R) (2013) ]

CURRICULUM VITAE

Education and Empolyment:

Oct. 2012 – present Postdoc, Physics department, University of Trento, Italy

Jun. 2010 – Jun. 2012 Postdoc, Institute for Advanced Study, Tsinghua University

Ph. D. Jun. 2010 School of Physics, Peking University (condensed matter theory)

M. S. Jun. 2006 School of Physics, Peking University (experiment on superconductivity)

Research interests:

Currently, I focus on theoretical studies of various many-body problems in ultracold quantum gases, especially the following aspects: BEC-BCS crossover near a Feshbach resonance, polaron physics in strongly interacting fermion-fermion mixtures and boson-fermion mixtures, the effects of spin-orbit coupling in quantum gases, etc.

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