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National Science Review

Sensitivity of quantum magnetic sensing

Liwei Lei, Teng Wu, Hong Mei Guo

Published Apr 3, 2025• 9 citations
Publisher

Abstract

Magnetometer, quantum or classical? Unveil the fundamental limit of magnetic field sensing.
DOI
10.1093/nsr/nwaf129

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We study experimentally the fundamental limits of sensitivity of an atomic radio-frequency magnetometer. First, we apply an optimal sequence of state preparation, evolution, and the backaction evading measurement to achieve a nearly projection noise limited sensitivity. We furthermore experimentally demonstrate that Einstein-Podolsky-Rosen entanglement of atoms generated by a measurement enhances the sensitivity to pulsed magnetic fields. We demonstrate this quantum limited sensing in a magnetometer utilizing a truly macroscopic ensemble of 1.5x10(12) atoms which allows us to achieve subfemtotesla/square root(Hz) sensitivity.
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