Ultrasensitive atomic comagnetometer with enhanced nuclear spin coherence

TL;DR

This paper introduces an ultrasensitive atomic comagnetometer with enhanced nuclear spin coherence, achieving unprecedented energy resolution and rotation sensitivity, enabling new physics searches beyond current limits.

Contribution

The study reveals a new relaxation mechanism and demonstrates a tenfold increase in nuclear spin hyperpolarization and coherence time, leading to ultrahigh sensitivity in a self-compensating comagnetometer.

Findings

Achieved a rotation sensitivity of 3×10⁻⁸ rad/s/Hz¹/².

Enhanced nuclear spin coherence time tenfold.

Projected sensitivity surpasses previous limits by over four orders of magnitude.

Abstract

Achieving high energy resolution in spin systems is important for fundamental physics research and precision measurements, with alkali-noble-gas comagnetometers being among the best available sensors. We found a new relaxation mechanism in such devices, the gradient of the Fermi-contact-interaction field that dominates the relaxation of hyperpolarized nuclear spins. We report on precise control over spin distribution, demonstrating a tenfold increase of nuclear spin hyperpolarization and transverse coherence time with optimal hybrid optical pumping. Operating in the self-compensation regime, our $^{21}$Ne-Rb-K comagnetometer achieves an ultrahigh inertial rotation sensitivity of $3\times10^{-8}$\,rad/s/Hz$^{1/2}$ in the frequency range from 0.2 to 1.0 Hz, which is equivalent to the energy resolution of $3.1\times 10^{-23}$\,eV/Hz$^{1/2}$. We propose to use this comagnetometer to search for exotic spin-dependent interactions involving proton and neutron spins. The projected sensitivity surpasses the previous experimental and astrophysical limits by more than four orders of magnitude.