Decoherence in quantum systems in a static gravitational field
  A small quantum system is studied which is a superposition of states localized in different positions in a static gravitational field. The time evolution of the correlation between different positions is investigated, and it is seen that there are two time scales for such an evolution (decoherence). Both time scales are inversely proportional to the red shift difference between the two points. These time scales correspond to decoherences which are linear and quadratic, respectively, in time. 
Ahmad Shariati, Mohammad Khorrami, Farhang Loran
quant-ph gr-qc