Dynamical response of Bose-Einstein condensates to oscillating gravitational fields

TL;DR

This paper explores how Bose-Einstein condensates respond dynamically to oscillating gravitational fields, identifying mechanisms for phonon creation and coupling, and suggests BECs could serve as sensitive detectors for tiny oscillating masses.

Contribution

It develops a model for BEC response to oscillating gravity, including damping, and proposes using BECs as sensors for small oscillating masses down to milligram scale.

Findings

Measurement of effects possible for milligram-scale masses

Coupling of phonon modes by oscillating gravitational fields

Potential for BECs to enable quantum gravity experiments

Abstract

A description of the dynamical response of uniformly trapped Bose-Einstein condensates (BECs) to oscillating external gravitational fields is developed, with the inclusion of damping. Two different effects that can lead to the creation of phonons in the BEC are identified; direct driving and parametric driving. Additionally, the oscillating gravitational field couples phonon modes, which can lead to the transition of excitations between modes. The special case of the gravitational field of a small, oscillating sphere located closely to the BEC is considered. It is shown that measurement of the effects may be possible for oscillating source masses down to the milligram scale, with a signal to noise ratio of the order of 10. To this end, noise terms and variations of experimental parameters are discussed and generic experimental parameters are given for specific atom species. The results of this article suggest the utility of BECs as sensors for the gravitational field of very small oscillating objects which may help to pave the way towards gravity experiments with masses in the quantum regime.