Constraints on a Spin-Dependent Exotic Interaction between Electrons with Single Electron Spin Quantum Sensors

TL;DR

This paper uses nitrogen-vacancy centers in diamond to set new laboratory bounds on hypothetical spin-dependent forces between electrons at micrometer scales, improving previous constraints significantly.

Contribution

It demonstrates a novel application of NV centers to constrain exotic electron-electron interactions, achieving more stringent bounds than prior experiments.

Findings

Established new upper bounds on axial-vector mediated electron interactions

Improved constraints at 500 μm range by an order of magnitude

Validated NV centers as effective sensors for detecting exotic forces

Abstract

A new laboratory bound on the axial-vector mediated interaction between electron spins at micrometer scale is established with single nitrogen-vacancy (NV) centers in diamond. A single crystal of $p$-terphenyl doped pentacene-$d_{14}$ under laser pumping provides the source of polarized electron spins. Based on the measurement of polarization signal via nitrogen-vacancy centers, we set a constraint for the exotic electron-electron coupling $g_A^eg_A^e$, within the force range from 10 to 900 $\mu$m. The obtained upper bound of the coupling at 500 $\mu$m is $|g_A^eg_A^e / 4\pi\hbar c |\leq 1.8\times 10^{-19} $, which is one order of magnitude more stringent than a previous experiment. Our result shows that the NV center can be a promising platform for searching for new particles predicted by theories beyond the standard model.