Searching for an exotic spin-dependent interaction with a single electron-spin quantum sensor

Xing Rong,Mengqi Wang,Chongwen Zou,Pengfei Wang,Pu Huang,Maosen Guo,Fazhan Shi,Yi-Fu Cai,Jiangfeng Du,Xi Qin,Yijin Xie,Man Jiao,Jianpei Geng

doi:10.1038/s41467-018-03152-9

Abstract

Searching for new particles beyond the standard model is crucial for understanding several fundamental conundrums in physics and astrophysics. Several hypothetical particles can mediate exotic spin-dependent interactions between ordinary fermions, which enable laboratory searches via the detection of the interactions. Most laboratory searches utilize a macroscopic source and detector, thus allowing the detection of interactions with submillimeter force range and above. It remains a challenge to detect the interactions at shorter force ranges. Here we propose and demonstrate that a near-surface nitrogen-vacancy center in diamond can be utilized as a quantum sensor to detect the monopole–dipole interaction between an electron spin and nucleons. Our result sets a constraint for the electron–nucleon coupling, g_{{mathrm{s}}}^{mathrm{N}}g_{mathrm{p}}^{mathrm{e}}, with the force range 0.1–23 μm. The obtained upper bound of the coupling at 20 μm is g_{{mathrm{s}}}^{mathrm{N}}g_{mathrm{p}}^{mathrm{e}} < 6.24 × 10−15.

Highlights

Searching for new particles beyond the standard model is crucial for understanding several fundamental conundrums in physics and astrophysics
The experimental investigation of this interaction at force range shorter than 20 μm, remains elusive due to the following challenges: (i) the size of the sensor should be small compared to the micrometer force range; (ii) the geometry of the sensor should allow close proximity between the sensor and the source; (iii) the sensitivity of the sensor should be sufficient for searching or for providing stringent bound for such interaction; (iv) the unwanted noises, such as the magnetic and electric field introduced by environment, should be isolated well
1 λr þ where r is the displacement vector between the electron and nucleon, r 1⁄4 jrj and er = r/r are the displacement and the unit displacement vector, gsN and gpe are the scalar and pseudoscalar coupling constants of the axion-like particles (ALPs) to the nucleon and to the electron, m is mass of the electron, λ = ħ/(mac) is the force range, ma is the mass of the ALP, σ is the Pauli vector of the electron spin, ħ is

Summary

Introduction

Searching for new particles beyond the standard model is crucial for understanding several fundamental conundrums in physics and astrophysics. A type of hypothetical ultralight scalars, such as axions or axion-like particles (ALPs)[2], has attracted a lot of attention in a wide variety of researches This has been well motivated for decades from the need of cosmology[3], namely, the dark matter candidate[4], the dark energy candidate[5], and from the understanding of the symmetries of charge conjugation and parity in quantum chromodynamics (QCD)[6] as well as predictions from fundamental theories such as string theory[1]. The method can be further extended to investigate other spin-dependent interactions[17] and opens the door for the single-spin quantum sensor to explore new physics beyond the standard model

Methods

Results

Conclusion