Quantum-enhanced differential atom interferometers and clocks with spin-squeezing swapping

TL;DR

This paper introduces a quantum-enhanced differential atom interferometry protocol using spin-squeezing swapping, achieving sub-SQL sensitivity by leveraging mode and particle entanglement, with potential applications in atomic clocks and interferometers.

Contribution

It presents a novel protocol employing mode-swapped spin-squeezed states for differential interferometry, surpassing standard quantum limit bounds.

Findings

Achieves sub-SQL sensitivity in differential phase estimation.

Utilizes mode and particle entanglement for enhanced measurement precision.

Demonstrates robustness through noise simulations in atomic clocks and interferometers.

Abstract

Thanks to common-mode noise rejection, differential configurations are crucial for realistic applications of phase and frequency estimation with atom interferometers. Currently, differential protocols with uncorrelated particles and mode-separable settings reach a sensitivity bounded by the standard quantum limit (SQL). Here we show that differential interferometry can be understood as a distributed multiparameter estimation problem and can benefit from both mode and particle entanglement. Our protocol uses a single spin-squeezed state that is mode-swapped among common interferometric modes. The mode swapping is optimized to estimate the differential phase shift with sub-SQL sensitivity. Numerical calculations are supported by analytical approximations that guide the optimization of the protocol. The scheme is also tested with simulation of noise in atomic clocks and interferometers.