# Searching for new particles beyond the standard model with a single electron-spin quantum sensor

## TL;DR

This paper introduces a novel quantum sensing method using a nitrogen-vacancy center to search for axion-like particles at short force ranges, setting new stringent constraints on their interactions.

## Contribution

The authors develop a single-spin quantum sensor technique to probe axion-mediated interactions at sub-20 micron ranges, surpassing previous experimental limits.

## Key findings

- Set new upper bounds for axion-electron-nucleon coupling at 20 μm.
- Achieved a two-order-of-magnitude improvement over previous constraints.
- Demonstrated the potential of quantum sensors for exploring physics beyond the standard model.

## Abstract

Searching for new particles beyond the standard model is crucial for understanding several fundamental conundrums in physics and astrophysics. Amongst them, axions or similar hypothetical pseudoscalar bosons would mediate electron-nucleon interactions. While previous experiments set stringent upper bounds of this interaction strength with force range over $20 ~\mu$m, experimental searching at shorter force range remains elusive. We develop a method that utilizes a near-surface Nitrogen-vacancy center as a quantum sensor to explore such interaction. New constraints for axion-mediated electron-nucleon coupling, $g_s^Ng_p^e$, have been set for the force range $0.1 $--$23~\mu$m. The obtained upper bound of the interaction at $20~\mu$m, $g_s^Ng_p^e < 6.24\times10^{-15}$, is two orders of magnitude more stringent than that set by earlier experiments. Our method can be further extended to investigate other spin-dependent interactions and opens the door for the single-spin quantum sensor to explore new physics beyond the standard model.