Nuclear-spin comagnetometer based on a liquid of identical molecules

TL;DR

This paper introduces a liquid-based nuclear-spin comagnetometer using identical molecules, significantly reducing magnetic gradient errors and enabling highly sensitive tests of spin-dependent gravitational interactions.

Contribution

The novel single-species comagnetometer suppresses magnetic gradient effects and enhances measurement sensitivity compared to traditional multi-species systems.

Findings

Suppresses magnetic field gradient dependence by over an order of magnitude.

Capable of measuring spin-dependent gravitational energy at the 10^{-17} eV level.

Potential to improve constraints on spin-gravity coupling by several orders of magnitude.

Abstract

Atomic comagnetometers are used in searches for anomalous spin-dependent interactions. Magnetic field gradients are one of the major sources of systematic errors in such experiments. Here we describe a comagnetometer based on the nuclear spins within an ensemble of identical molecules. The dependence of the measured spin-precession frequency ratio on the first-order magnetic field gradient is suppressed by over an order of magnitude compared to a comagnetometer based on overlapping ensembles of different molecules. Our single-species comagnetometer is shown to be capable of measuring the hypothetical spin-dependent gravitational energy of nuclei at the $10^{-17}$ eV level, comparable to the most stringent existing constraints. Combined with techniques for enhancing the signal such as parahydrogen-induced polarization, this method of comagnetometry offers the potential to improve constraints on spin-gravity coupling of nucleons by several orders of magnitude.