Surpassing the Standard Quantum Limit in an Atom Interferometer with Four-mode Entanglement Produced from Four-Wave Mixing

TL;DR

This paper proposes a theoretical scheme using four-wave mixing to generate four-mode entanglement in atom interferometry, enabling measurements that surpass the standard quantum limit by exploiting correlations between two interferometers.

Contribution

It introduces a novel four-mode entanglement scheme for atom interferometry that surpasses the standard quantum limit by utilizing correlations between two interferometers.

Findings

Scheme can surpass the standard quantum limit using four-mode entanglement.

Utilizes all available atoms in the interferometry process.

Correlations between two interferometers enable enhanced measurement precision.

Abstract

We theoretically investigate a scheme for atom interferometry that surpasses the standard quantum limit. A four-wave mixing scheme similar to the recent experiment performed by Pertot et al. \cite{pertot} is used to generate sub-shot noise correlations between two modes. These two modes are then interfered with the remaining two modes in such a way as to surpass the standard quantum limit, whilst utilising all of the available atoms. Our scheme can be viewed as using two correlated interferometers. That is, the signal from each interferometer when looked at individually is classical, but there are correlations between the two interferometers that allow for the standard quantum limit to be surpassed.