Room Temperature Initialisation and Readout of Intrinsic Spin Defects in a Van der Waals Crystal

TL;DR

This study demonstrates room temperature optical initialization and readout of intrinsic spin defects in hexagonal boron nitride, advancing 2D materials as promising platforms for quantum technologies.

Contribution

The paper provides the first experimental observation of optically addressable spin states in 2D hBN, including spin resonance and polarization at room temperature.

Findings

Identification of negatively charged boron vacancy in hBN.

Observation of optically detected magnetic resonance at room temperature.

Demonstration of spin polarization under optical pumping.

Abstract

Optically addressable spins in widebandgap semiconductors have become one of the most prominent platforms for exploring fundamental quantum phenomena. While several candidates in 3D crystals including diamond and silicon carbide have been extensively studied, the identification of spindependent processes in atomically thin 2D materials has remained elusive. Although optically accessible spin states in hBN are theoretically predicted, they have not yet been observed experimentally. Here, employing rigorous electron paramagnetic resonance techniques and photoluminescence spectroscopy, we identify fluorescence lines in hexagonal boron nitride associated with a particular defect, the negatively charged boron vacancy and determine the parameters of its spin Hamiltonian. We show that the defect has a triplet ground state with a zero field splitting of 3.5 GHz and establish that the centre exhibits optically detected magnetic resonance at room temperature. We also demonstrate the spin polarization of this centre under optical pumping, which leads to optically induced population inversion of the spin ground state a prerequisite for coherent spin manipulation schemes. Our results constitute a leap forward in establishing two dimensional hBN as a prime platform for scalable quantum technologies, with extended potential for spin based quantum information and sensing applications, as our ODMR studies on hBN NV diamonds hybrid structures show.