Cold atoms with laser-induced spin-orbit (SO) interactions provide intriguing new platforms to explore novel quantum physics beyond natural conditions of solids. Recent experiments demonstrated one-dimensional (1D) SO couplings for bosons and fermions. However, the realization of 2D SO interaction for quantum degenerate atom gases is much more interesting and challenging. Here we report the realization of 2D SO coupling and topological band for ultracold 87Rb gas through an optical Ramanlattice technique. A controllable crossover between 2D and 1D SO couplings is studied, and the SO effects and topological phase diagram are observed by measuring the atomic cloud distribution and spin texture in momentum space. Furthermore, the quantum quench dynamics of the Bose gas with 2D SO coupling is studied, lead to interesting non-equilibrium phenomenon. Our 2D SO coupled Bose gas opens a broad way in cold atoms to study exotic quantum phases, including the highly-sought-after topological superfluids.
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Bose-Einstein Condensate, Science 354, 83 (2016)
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arXiv:1706.08961