Estimation of gravitational acceleration with quantum optical interferometers

TL;DR

This paper explores using quantum optical interferometers, including Mach-Zehnder and SU(1,1) types, to improve the precision of gravitational acceleration measurements, highlighting advantages of active interferometers with squeezing under realistic losses.

Contribution

It introduces a quantum optical setup for gravitational acceleration estimation, comparing standard and active interferometers, and demonstrates potential advantages with current technology.

Findings

SU(1,1) interferometers outperform Mach-Zehnder with single-mode squeezing at >8% loss.

The proposed system can test quantum theory and general relativity intersection.

Current technology enables practical implementation of the proposed measurement scheme.

Abstract

The precise estimation of the gravitational acceleration is important for various disciplines. We consider making such an estimation using quantum optics. A Mach-Zehnder interferometer in an "optical fountain" type arrangement is considered and used to define a standard quantum limit for estimating the gravitational acceleration. We use an approach based on quantum field theory on a curved, Schwarzschild metric background to calculate the coupling between the gravitational field and the optical signal. The analysis is extended to include the injection of a squeezed vacuum to the Mach-Zehnder arrangement and also to consider an active, two-mode SU(1,1) interferometer in a similar arrangement. When detection loss is larger than $8\%$, the SU(1,1) interferometer shows an advantage over the MZ interferometer with single-mode squeezing input. The proposed system is based on current technology and could be used to examine the intersection of quantum theory and general relativity as well as for possible applications.