Nuclear Spin Assisted Magnetic Field Angle Sensing

TL;DR

This paper introduces a nuclear spin-assisted method for NV center quantum sensors, enabling magnetic field angle detection and noise decoupling even when the bias magnetic field is perpendicular to the NV axis.

Contribution

The study presents a novel entanglement-based sensing strategy that restores magnetic sensitivity and reveals directional noise properties in NV center quantum sensors.

Findings

Restores magnetic field sensitivity at perpendicular bias fields.

Enables detection of small magnetic field angle changes.

Uncovers anisotropic noise characteristics and enhances coherence.

Abstract

Quantum sensing exploits the strong sensitivity of quantum systems to measure small external signals. The nitrogen-vacancy (NV) center in diamond is one of the most promising platforms for real-world quantum sensing applications, predominantly used as a magnetometer. However, its magnetic field sensitivity vanishes when a bias magnetic field acts perpendicular to the NV axis. Here, we introduce a novel sensing strategy assisted by the nitrogen nuclear spin that uses the entanglement between the electron and nuclear spins to restore the magnetic field sensitivity. This, in turn, allows us to detect small changes in the magnetic field angle relative to the NV axis. Furthermore, based on the same underlying principle, we show that the NV coupling strength to magnetic noise, and hence its coherence time, exhibits a strong asymmetric angle dependence. This allows us to uncover the directional properties of the local magnetic environment and to realize maximal decoupling from anisotropic noise.