Enhanced quantum magnetometry with a laser-written integrated photonic diamond chip

TL;DR

This paper presents a laser-written diamond photonic chip with high-density nitrogen-vacancy centers that significantly enhances quantum magnetometry sensitivity, enabling more precise microscale magnetic field detection under ambient conditions.

Contribution

It introduces a high-quality laser-written waveguide in diamond with dense NV centers that maintains spin coherence and improves magnetic sensing sensitivity over traditional methods.

Findings

Achieved 63 pT·Hz^{-1/2} DC magnetic field sensitivity.

Demonstrated at least tenfold sensitivity improvement over conventional setups.

Maintained NV center coherence properties in the waveguide.

Abstract

An ensemble of negatively charged nitrogen-vacancy centers in diamond can act as a precise quantum sensor even under ambient conditions. In particular, to optimize thier sensitivity, it is crucial to increase the number of spins sampled and maximize their coupling to the detection system, without degrading their spin properties. In this paper, we demonstrate enhanced quantum magnetometry via a high-quality buried laser-written waveguide in diamond with a 4.5 ppm density of nitrogen-vacancy centers. We show that the waveguide-coupled nitrogen-vacancy centers exhibit comparable spin coherence properties as that of nitrogen-vacancy centers in pristine diamond using time-domain optically detected magnetic resonance spectroscopy. Waveguide-enhanced magnetic field sensing is demonstrated in a fiber-coupled integrated photonic chip, where probing an increased volume of high-density spins results in 63 pT$.$Hz $^{-1/2}$ of DC-magnetic field sensitivity and 20 pT$.$Hz $^{-1/2}$ of AC magnetic field sensitivity. This on-chip sensor realizes at least an order of magnitude improvement in sensitivity compared to the conventional confocal detection setup, paving the way for microscale sensing with nitrogen-vacancy ensembles.