Multi-species optically addressable spin defects in a van der Waals material

TL;DR

This paper demonstrates the coexistence and interaction of two different optically addressable spin defects in hexagonal boron nitride, enabling room-temperature quantum control, magnetic imaging, and potential quantum sensing applications.

Contribution

It reveals the presence of two distinct spin species in hBN, shows their coherent control and coupling, and demonstrates their use in magnetic imaging at room temperature.

Findings

Identification of $S=1$ boron vacancy and $S=1/2$ emitter spins in hBN

Observation of strong dipolar coupling between spin species

Successful magnetic imaging using $S=1/2$ defects

Abstract

Optically addressable spin defects hosted in two-dimensional van der Waals materials represent a new frontier for quantum technologies, promising to lead to a new class of ultrathin quantum sensors and simulators. Recently, hexagonal boron nitride (hBN) has been shown to host several types of optically addressable spin defects, thus offering a unique opportunity to simultaneously address and utilise various spin species in a single material. Here we demonstrate an interplay between two separate spin species within a single hBN crystal, namely $S=1$ boron vacancy defects and visible emitter spins. We unambiguously prove that the visible emitters are $S=\frac{1}{2}$ spins and further demonstrate room temperature coherent control and optical readout of both spin species. Importantly, by tuning the two spin species into resonance with each other, we observe cross-relaxation indicating strong inter-species dipolar coupling. We then demonstrate magnetic imaging using the $S=\frac{1}{2}$ defects, both under ambient and cryogenic conditions, and leverage their lack of intrinsic quantization axis to determine the anisotropic magnetic susceptibility of a test sample. Our results establish hBN as a versatile platform for quantum technologies in a van der Waals host at room temperature.