Matter-wave coherence limit owing to cosmic gravitational wave background

TL;DR

This paper investigates how a stochastic gravitational wave background imposes fundamental limits on matter-wave interferometry, especially for macroscopic objects, due to decoherence effects predicted by inflationary cosmology models.

Contribution

It demonstrates that a scale-invariant gravitational wave background sets a size limit on observable matter-wave interference, highlighting the need for advanced control methods to observe macroscopic quantum effects.

Findings

Interference cannot be observed for objects larger than 1-10 mm without control measures.

A stochastic gravitational wave background causes decoherence in matter-wave interferometry.

Limits are estimated for ordinary matter moving at speeds much less than c.

Abstract

We study matter-wave interferometry in the presence of a stochastic background of gravitational waves. It is shown that if the background has a scale-invariant spectrum over a wide bandwidth (which is expected in a class of inflationary models of Big Bang cosmology), then separated-path interference cannot be observed for a lump of matter of size above a limit which is very insensitive to the strength and bandwidth of the fluctuations, unless the interferometer is servo-controlled or otherwise protected. For ordinary solid matter this limit is of order 1--10 mm. A servo-controlled or cross-correlated device would also exhibit limits to the observation of macroscopic interference, which we estimate for ordinary matter moving at speeds small compared to c.