Polarization squeezing of light by single passage through an atomic   vapor
  We have studied relative-intensity fluctuations for a variable set of orthogonal elliptic polarization components of a linearly polarized laser beam traversing a resonant $^{87}$Rb vapor cell. Significant polarization squeezing at the threshold level (-3dB) required for the implementation of several continuous variables quantum protocols was observed. The extreme simplicity of the setup, based on standard polarization components, makes it particularly convenient for quantum information applications. 
S. Barreiro, P. Valente, H. Failache and A. Lezama
quant-ph physics.atom-ph