Magdalena Zych, Fabio Costa, Igor Pikovski, Timothy C. Ralph, Caslav Brukner
Predictions of general relativity have been extensively confirmed in many experiments. However, the influence of gravity on quantum systems has only been tested in the Newtonian limit of the theory. Here we discuss a quantum interference experiment with single photons that can probe the interplay between quantum mechanics and general relativity. Because of the general relativistic time dilation, a light signal takes longer when it passes close to a massive body - an effect known as the Shapiro delay. We consider a single photon travelling in superposition along two paths in an interferometer with each arm at a different height in a homogeneous gravitational field. If the time dilation is comparable with the photon's coherence time the visibility of the quantum interference is predicted to drop, while for shorter time dilations the effect of gravity will result in a relative phase shift between the two arms. We discuss under which conditions such experiments can only be explained if both general relativity and quantum mechanics apply. Their experimental feasibility is analyzed and we conclude that for photons the observation of the gravitationally induced phase shift is within reach of current technology.
View original:
http://arxiv.org/abs/1206.0965
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