Effect of Induced Spin-Orbit Coupling for Atoms via Laser Fields
  We propose an experimental scheme to study spin-orbit coupling effects in a of two-dimensional (2D) Fermi atomic gas cloud by coupling its internal electronic states (pseudospins) to radiation in a delta configuration. The induced spin-orbit coupling can be of the Dresselhaus and Rashba type with and without a Zeeman term. We show that the optically induced spin-orbit coupling can lead to a spin-dependent effective mass under appropriate condition, with one of them able to be tuned between positive and negative effective mass. As a direct observable we show that in the expansion dynamics of the atomic cloud the initial atomic cloud splits into two clouds for the positive effective mass case regime, and into four clouds for the negative effective mass regime. 
Xiong-Jun Liu, Mario F. Borunda, Xin Liu and Jairo Sinova