Quantum gravitational decoherence of matter waves

TL;DR

This paper proposes a new approach to gravitational decoherence near the Planck scale, linking matter wave coherence loss to quantum spacetime fluctuations, and suggests that advanced interferometers could soon probe quantum gravity effects.

Contribution

It introduces a gravitational analogue of Brownian motion based on conformal structure of canonical gravity, connecting matter wave decoherence to quantum spacetime fluctuations.

Findings

Minimum scaling factor within expected quantum gravity range

Matter wave interferometers approaching sensitivity to Planck scale effects

Potential for near-future experimental investigation of quantum gravity

Abstract

One of the biggest unsolved problems in physics is the unification of quantum mechanics and general relativity. The lack of experimental guidance has made the issue extremely evasive, though various attempts have been made to relate the loss of matter wave coherence to quantum spacetime fluctuations. We present a new approach to the gravitational decoherence near the Planck scale, made possible by recently discovered conformal structure of canonical gravity. This leads to a gravitational analogue of the Brownian motion whose correlation length is given by the Planck length up to a scaling factor. With input from recent matter wave experiments, we show that the minimum value of this factor to be well within the expected range for quantum gravity theories. This suggests that the sensitivities of advanced matter wave interferometers may be approaching the fundamental level due to quantum spacetime fluctuations and that investigating Planck scale physics using matter wave interferometry may become a reality in the near future.