Decoherence due to gravitational time dilation: analysis of competing   decoherence effects
  Recently, a static gravitational field, such as that of the Earth, was proposed as a new source of decoherence [1]. We study the conditions under which it becomes the dominant decoherence effect in typical interferometric experiments. The following competing sources are considered: spontaneous emission of light, absorption, scattering with the thermal photons and collisions with the residual gas. We quantify all these effects. As we will see, current experiments are off by several orders of magnitude. New ideas are needed in order to achieve the necessary requirements: having as large as system as possible, to increase gravitational decoherence, cool it and isolated well enough to reduce thermal and collisional decoherence, and resolve very small distances. 
Matteo Carlesso and Angelo Bassi
quant-ph