Transport of Entanglement
  We consider the propagation of two-photon light in a random medium. We show that the Wigner distribution of the two-photon wave function obeys an equation that is analogous to the radiative transport equation for classical light. Using this result, we predict that the entanglement of a photon pair is destroyed with propagation. 
Manabu Machida, Vadim A Markel and John C Schotland
physics.optics quant-ph