Squeezing Enhancement in Lossy Multi-Path Atom Interferometers

TL;DR

This paper demonstrates that optimized spin-squeezed states can significantly enhance the sensitivity of lossy multi-path atom interferometers, advancing quantum metrology despite practical limitations.

Contribution

It introduces a generalized formalism for realistic, lossy atom interferometers and evaluates how spin squeezing can improve sensitivity under practical conditions.

Findings

Sensitivity improved by several dB over standard quantum limit

Finite temperature reduces the benefits of entanglement

Optimized parameters can mitigate effects of losses

Abstract

This paper explores the sensitivity gains afforded by spin-squeezed states in atom interferometry, in particular using Bragg diffraction. We introduce a generalised input-output formalism that accurately describes realistic, non-unitary interferometers, including losses due to velocity selectivity and scattering into undesired momentum states. This formalism is applied to evaluate the performance of one-axis twisted spin-squeezed states in improving phase sensitivity. Our results show that by carefully optimising the parameters of the Bragg beam splitters and controlling the degree of squeezing, it is possible to improve the sensitivity of the interferometer by several dB with respect to the standard quantum limit despite realistic levels of losses in light pulse operations. However, the analysis also highlights the challenges associated with achieving these improvements in practice, most notably the impact of finite temperature on the benefits of entanglement. The results suggest ways of optimising interferometric setups to exploit quantum entanglement under realistic conditions, thereby contributing to advances in precision metrology with atom interferometers.