Entanglement-enhanced Synchronous differential comparison

TL;DR

This paper proposes using entangled atoms in synchronous differential measurements to significantly improve the sensitivity of spatial-shift detection, with potential applications in gravitational redshift detection.

Contribution

It introduces novel methods of engineering entangled atoms for enhanced measurement sensitivity, surpassing the standard quantum limit in spatial-shift detection.

Findings

Sensitivity enhancement factor of 1.4 within an entangled atomic cloud.

Strong sensitivity boost of approximately 9.7 with 1000 entangled atoms per pixel.

Potential for further sensitivity improvements with larger atom numbers.

Abstract

The quantum entanglement enables the precision measurement and frequency metrology beyond the standard quantum limit that is imposed by the quantum projection noise and photon shot noise. Here we propose employing the entangled atoms in the synchronous differential measurement to enhance the sensitivity of the spatial-shift detection. Two ways of engineering the entangled atoms are studied. The synchronous comparison between two pixels within an entangled atomic cloud leads to a sensitivity enhancement factor of 1.4 over the standard quantum limit. Increasing the atom number hardly further improves the sensitivity. In contrast, the synchronous comparison between two independent pixels that are individually composed of entangled atoms allows for a strong sensitivity enhancement by a factor of, for example, 9.7 with $10^{3}$ entangled atoms in each pixel, corresponding to a reduction of the averaging time by a factor of about $10^{2}$. A large atom number may further elevate the sensitivity. Our work paves the way towards the entanglement-enhanced detection of the gravitational redshift by means of the \emph{in situ} imaging spectroscopy.