Nuclear spin assisted magnetic field angle sensing

Ziwei Qiu,Uri Vool,Assaf Hamo,Amir Yacoby

doi:10.1038/s41534-021-00374-6

Ziwei Qiu, Uri Vool + Show 2 more

Open Access

https://doi.org/10.1038/s41534-021-00374-6

Copy DOI

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 different 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.

Highlights

Quantum sensing harnesses the coherence of well-controlled quantum systems to detect small signals with high sensitivity[1,2,3].Typically, an external signal directly leads to a shift of the quantum sensor’s energy levels
Similar to the hyperfine interaction, we show that the coupling between the electron spin and magnetic noise sensitively depends on the bias field angle, which can be further employed to distinguish and characterize anisotropic noise in the environment
The NV spin ground state Hamiltonian Hgs can be written as: Hgs 1⁄4 He þ Hn He 1⁄4 DgsS2z þ γBðBxSx þ BzSzÞ Hn 1⁄4 IÁAÁSþ γNðBxIx þ BzIzÞ; where He and Hn denote the Hamiltonians associated with the electron spin (S = 1) and 15N nuclear spin (I 1⁄4 12), respectively

Summary

Introduction

Quantum sensing harnesses the coherence of well-controlled quantum systems to detect small signals with high sensitivity[1,2,3].Typically, an external signal directly leads to a shift of the quantum sensor’s energy levels. The electron spin associated with the negatively charged NV center has long coherence time even at room temperature and is capable of detecting a variety of signals with high sensitivity and nanoscale resolution. These include magnetic[18,19,20] and electric fields[21,22,23,24,25,26,27,28], temperature[29,30,31,32], and pressure[33,34,35]

Methods

Results

Conclusion