Pumped-up SU(1,1) interferometry

TL;DR

The paper introduces a pumped-up SU(1,1) interferometry approach that involves all input particles in phase measurement, surpassing shot-noise limits and maintaining robustness against losses and noise, thus enhancing quantum sensing capabilities.

Contribution

It proposes a novel pumped-up scheme for SU(1,1) interferometry that improves absolute sensitivity and robustness over traditional methods, applicable to spinor BECs and hybrid atom-light systems.

Findings

Pumped-up schemes surpass shot-noise limit with total input particles.

They outperform conventional SU(1,1) interferometry in robustness.

The approach remains effective despite particle losses and detection noise.

Abstract

Although SU(1,1) interferometry achieves Heisenberg-limited sensitivities, it suffers from one major drawback: only those particles outcoupled from the pump mode contribute to the phase measurement. Since the number of particles outcoupled to these `side modes' is typically small, this limits the interferometer's absolute sensitivity. We propose an alternative `pumped-up' approach where all the input particles participate in the phase measurement, and show how this can be implemented in spinor Bose-Einstein condensates and hybrid atom-light systems - both of which have experimentally realized SU(1,1) interferometry. We demonstrate that pumped-up schemes are capable of surpassing the shot-noise limit with respect to the total number of input particles and are never worse than conventional SU(1,1) interferometry. Finally, we show that pumped-up schemes continue to excel - both absolutely and in comparison to conventional SU(1,1) interferometry - in the presence of particle losses, poor particle-resolution detection, and noise on the relative phase difference between the two side modes. Pumped-up SU(1,1) interferometry therefore pushes the advantages of conventional SU(1,1) interferometry into the regime of high absolute sensitivity, which is a necessary condition for useful quantum-enhanced devices.