Thermal Light as a Mixture of Sets of Pulses: the Quasi-1D Example
  The relationship between thermal light and coherent pulses is of fundamental and practical interest. We now know that thermal light cannot be represented as a statistical mixture of single pulses. In this paper we ask whether or not thermal light can be represented as a statistical mixture of sets of pulses. We consider thermal light in a one-dimensional wave-guide, and find a convex decomposition into products of orthonormal coherent states of localized, nonmonochromatic modes. 
Agata M. Branczyk, Aurelia Chenu and J. E. Sipe
quant-ph physics.chem-ph physics.optics