Geometric phase magnetometry using a solid-state spin

TL;DR

This paper demonstrates a novel geometric-phase magnetometry technique using NV centers in diamond, achieving a 400-fold increase in magnetic field range and enhanced sensitivity, overcoming limitations of traditional interferometry-based methods.

Contribution

The study introduces a geometric-phase approach to magnetometry that unravels phase ambiguity and decouples sensitivity from field range, with experimental validation using NV centers.

Findings

Achieved about 400 times larger magnetic field range.

Enhanced sensitivity in the nonadiabatic regime.

Demonstrated geometric-phase magnetometry with NV centers.

Abstract

Magnetometry is a powerful technique for the non-invasive study of biological and physical systems. A key challenge lies in the simultaneous optimization of magnetic field sensitivity and maximum field range. In interferometry-based magnetometry, a quantum two-level system acquires a dynamic phase in response to an applied magnetic field. However, due to the 2{\pi} periodicity of the phase, increasing the coherent interrogation time to improve sensitivity results in reduced field range. Here we introduce a route towards both large magnetic field range and high sensitivity via measurements of the geometric phase acquired by a quantum two-level system. We experimentally demonstrate geometric-phase magnetometry using the optically addressable electronic spin associated with the nitrogen vacancy (NV) color center in diamond. Our approach enables unwrapping of the 2{\pi} phase ambiguity, decoupling of magnetic field range from sensitivity, and enhancement of the field range by about 400 times. We also find additional improvement in sensitivity in the nonadiabatic regime, and study how geometric-phase decoherence depends on adiabaticity. Our results show that the geometric phase can be a versatile tool for quantum sensing applications.