主讲人: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, realization of 2D SO interaction for quantum degenerate atom gases, a much more important task, remains very challenging. Here we propose and experimentally realize, for the first time, 2D SO coupling and topological band for 87Rb degenerate gas through an optical Raman lattice, without phase locking or fine tuning of optical potentials. A controllable crossover between 2D and 1D SO couplings is studied, and the SO effects and nontrivial band topology are observed by measuring the atomic cloud distribution and spin texture in momentum space. Our realization of 2D SO coupling with advantages of small heating and topological stability opens a broad avenue in cold atoms to study exotic quantum phases, including the highly-sought-after topological superfluids.