Comagnetometer probes of dark matter and new physics

TL;DR

Comagnetometry is a highly sensitive technique for detecting new physics beyond the Standard Model, capable of probing phenomena like dark matter, Lorentz violation, and EDMs with potential for significant sensitivity improvements.

Contribution

This paper reviews the use of comagnetometry for exploring new physics, discusses its current sensitivity, and evaluates prospects for substantial future enhancements.

Findings

Current sensitivities reach 10^{-26} eV energy differences.

Potential for several orders of magnitude improvement based on existing technology.

Systematic errors and instabilities are identified as key limiting factors.

Abstract

We discuss the use of comagnetometry in studying new physics that couples to fermionic spin. Modern comagnetometry is -- in absolute energy units -- the most sensitive experimental technique for measuring the energy difference between quantum states, reaching sensitivities in the $10^{-26}\,$eV range. The technique suppresses the magnetic interactions of the spins, making searches for non-standard-model interactions possible. Many implementations have been developed and optimized for various uses. New physics scenarios which can be probed with comagnetometers include: EDMs, violations of Lorentz invariance, Goldstone bosons of new high-energy symmetries, CP-violating long-range forces, and axionic dark matter. We consider the prospects for improvements in the technique, and show -- based purely on signal-to-noise ratio with existing technology -- that there is room for several orders of magnitude in further improvement. We also evaluate several sources of systematic error and instability that may limit improvements.