Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong, China.
Phys Rev Lett. 2018 Sep 21;121(12):120403. doi: 10.1103/PhysRevLett.121.120403.
In this Letter, we investigate spin dynamics of a two-component Bose gas with spin-orbit coupling realized in cold atom experiments. We derive coupled hydrodynamic equations for number and spin densities as well as their associated currents. Specializing to the quasi-one-dimensional situation, we obtain analytic solutions of the spin helix structure and its dynamics in both adiabatic and diabatic regimes. In the adiabatic regime, the transverse spin decays parabolically in the short-time limit and exponentially in the long-time limit, depending on initial polarization. In contrast, in the diabatic regime, transverse spin density and current oscillate in a way similar to the charge-current oscillation in an undamped LC circuit. The effects of Rabi coupling on the short-time spin dynamics is also discussed. Finally, using realistic experimental parameters for ^{87}Rb, we show that the timescales for spin dynamics is of the order of milliseconds to a few seconds and can be observed experimentally.
在这篇快报中，我们研究了冷原子实验中实现的具有自旋轨道耦合的双分量玻色气体的自旋动力学。我们推导出了数密度和自旋密度以及它们相关电流的耦合流体力学方程。特别地，针对准一维情况，我们获得了自旋螺旋结构及其在绝热和非绝热两种情况下的动力学的解析解。在绝热情况下，横向自旋在短时间极限下呈抛物线衰减，在长时间极限下呈指数衰减，这取决于初始极化。相比之下，在非绝热情况下，横向自旋密度和电流的振荡方式类似于无阻尼 LC 电路中的电荷电流振荡。我们还讨论了拉比耦合对短时间自旋动力学的影响。最后，使用^{87}Rb 的实际实验参数，我们表明自旋动力学的时间尺度为毫秒到几秒钟量级，可以在实验中观察到。
