A Remotely Interrogated All-Optical $^{87}$Rb Magnetometer

TL;DR

This paper demonstrates a remote all-optical atomic magnetometer capable of measuring Earth's magnetic field over ten meters with high precision, using laser beams to excite and detect $^{87}$Rb resonance without direct contact.

Contribution

It introduces a novel remote interrogation technique for atomic magnetometry using laser beams over free space, enabling non-contact magnetic field measurements at a distance.

Findings

Achieved geomagnetic field measurement with ~3.5 pT precision in 2 seconds.

Operated in self-oscillating mode with 5.3 pT/√Hz noise floor.

Remote interrogation over ten meters demonstrated feasibility for practical applications.

Abstract

Atomic magnetometry was performed at Earth's magnetic field over a free-space distance of ten meters. Two laser beams aimed at a distant alkali-vapor cell excited and detected the $^{87}$Rb magnetic resonance, allowing the magnetic field within the cell to be interrogated remotely. Operated as a driven oscillator, the magnetometer measured the geomagnetic field with \lessgtrsim{\lesssim}3.5\,pT precision in a $\sim$2\,s data acquisition; this precision was likely limited by ambient field fluctuations. The sensor was also operated in self-oscillating mode with a 5.3\,pT/$\sqrt{\textrm{Hz}}$ noise floor. Further optimization will yield a high-bandwidth, fully remote magnetometer with sub-pT sensitivity.