Self-Organization Threshold Scaling for Thermal Atoms Coupled to a   Cavity
  We make a detailed experimental study of the threshold for the self-organization of thermal 87Rb atoms coupled to a high-finesse cavity over a range of atom numbers and cavity detunings. We investigate the difference between probing with a traveling wave and a retroreflected lattice. These two scenarios lead to qualitatively different behavior in terms of the response of the system as a function of cavity detuning with respect to the probe. In both cases, we confirm a N-1 scaling of the threshold with atom number. 
K. J. Arnold, M. P. Baden, M. D. Barrett
physics.atom-ph quant-ph