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The spin-orbit (SO) interaction plays essential roles in many prominent quantum effects, with which the important topics including spintronics, topological insulators, and topological superconductors emerge in the past over decade. On the other hand, cold atoms with laser-induced SO interactions provide an intriguing new platform to explore quantum physics beyond natural conditions of solids. In the work presented here we propose in theory and realize in experiment 2D SO coupling and nontrivial topological band for 87Rb quantum degenerate gas through an optical Raman lattice, without phase locking or fine tuning of optical potentials. After introducing the background of the SO coupling for cold atoms, we present the optical Raman lattice scheme for the generation of SO coupling and topological phases for cold atoms, as being applied to latest theoretical and experimental work. A controllable crossover between 2D and 1D SO couplings is studied, and the SO effects and nontrivial band Chern numbers 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 may open a broad avenue in cold atoms to study exotic quantum phases. Future important issues in theory and experiment will also be introduced.
Reference:
Z. Wu, L. Zhang, W. Sun, X. Xu, B. Wang, Y. Deng, S. Chen, X. -J. Liu and J. -W. Pan, Science, 354, 83-88 (2016). |
