Fluctuations of spacetime and holographic noise in atomic interferometry

On small scales spacetime can be understood as some kind of spacetime foam of fluctuating bubbles or loops which are expected to be an outcome of a theory of quantum gravity. One recently discussed model for this kind of spacetime fluctuations is the holographic principle which allows to deduce the structure of these fluctuations. We review and discuss two scenarios which rely on the holographic principle leading to holographic noise. One scenario leads to fluctuations of the spacetime metric affecting the dynamics of quantum systems: (i) an apparent violation of the equivalence principle, (ii) a modification of the spreading of wave packets, and (iii) a loss of quantum coherence. All these effects can be tested with cold atoms.