Frequency Range Boosted Magnetometry Beyond the Spin Coherence Limit via Compressive Sensing

TL;DR

This paper introduces a compressive sensing-based method that extends the frequency range of spin magnetometry beyond the traditional spin coherence limit, enabling high-sensitivity, broad-bandwidth magnetic field sensing without aliasing.

Contribution

It presents a novel technique using compressive sensing to surpass the spin coherence limit in frequency resolution for FID magnetometry.

Findings

Expanded frequency range from 251 Hz to 3000 Hz

Avoided frequency aliasing in measurements

Enhanced sensitivity and bandwidth in magnetic sensing

Abstract

Free induction decay (FID) of spin precession serves as an essential tool for quantum sensing across diverse platforms. While extending spin coherence time remains critical for sensitivity enhancement, the requisite long single-shot acquisitions narrow the resolvable frequency range, establishing a fundamental ``spin coherence limit (SCL)'', according to the Nyquist Sampling Theorem. Besides, conventional spectral analysis for FID measurement suffers from frequency alias, causing signal attenuation and positional errors that compromise the measurement validity. Here, we demonstrate a general frequency-range-extended technique that overcomes SCL by leveraging compressive sensing. By applying this method to the FID magnetometer, we expand the resolvable frequency range significantly from the Nyquist-limited range of 251\,Hz to 3000\,Hz, effectively avoiding frequency alias. Our work paves the way for implementing long-coherence-time spin systems in high-sensitivity, broad-bandwidth, and alias-free magnetic field sensing.