Quantum Enhanced Magnetometer with Low-Frequency Squeezing

TL;DR

This paper demonstrates a quantum-enhanced magnetometer that achieves noise reduction below the shot-noise level using squeezed vacuum states, with applications in sensitive magnetic field detection.

Contribution

The work introduces a magnetometer leveraging low-frequency squeezing to surpass shot-noise limits, highlighting two operational regimes and advancing quantum sensing technology.

Findings

Achieved 2 dB noise reduction with squeezed vacuum injection.

Identified two operational regimes: quantum noise limited and laser noise influenced.

Demonstrated broadband noise reduction from 100 Hz to several MHz.

Abstract

We report the demonstration of a magnetometer with noise-floor reduction below the shot-noise level. This magnetometer, based on a nonlinear magneto-optical rotation effect, is enhanced by the injection of a squeezed vacuum state into its input. The noise spectrum shows squeezed noise reduction of about 2 dB spanning from close to 100 Hz to several megahertz. We also report on the observation of two different regimes of operation of such a magnetometer: one in which the detection noise is limited by the quantum noise of the light probe only, and one in which we see additional noise originating from laser noise which is rotated into the vacuum polarization.