Inducing electron spin coherence in GaAs quantum well waveguides: Spin   coherence without spin precession
  Electron spin coherence is induced via light-hole transitions in a quantum well waveguide without either an external or internal DC magnetic field. In the absence of spin precession, the induced spin coherence is detected through effects of quantum interference in the spectral domain coherent nonlinear optical response. We interpret the experimental results qualitatively using a simple few-level model with only the optical transition selection rule as its basic ingredients. 
Susanta Sarkar, Phedon Palinginis, Hailin Wang, Pei-Cheng Ku, Connie   J. Chang-Hasnain, N.H. Kwong, and R. Binder