Electron-nuclear coherent coupling and nuclear spin readout through optically polarized VB- spin states in hBN

TL;DR

This study demonstrates that negatively charged boron vacancies in hBN exhibit coherent electron-nuclear coupling and allow nuclear spin readout, advancing their potential for quantum technology applications.

Contribution

It provides experimental evidence of electron-nuclear coherence and coupling in VB- defects in hBN, supported by theoretical calculations, highlighting their quantum technological relevance.

Findings

Hahn-echo coherence time Tcoh = 15 μs

Detection of MHz-range modulation from nuclear quadrupole interaction

Electron-nuclear coupling confined to defective layer

Abstract

Coherent coupling of defect spins with surrounding nuclei along with the endowment to read out the latter, are basic requirements for an application in quantum technologies. We show that negatively charged boron vacancies (VB-) in electron-irradiated hexagonal boron nitride (hBN) meet these prerequisites. We demonstrate Hahn-echo coherence of the VB- electron spin with a characteristic decay time Tcoh = 15 us, close to the theoretically predicted limit of 18 us for spin defects in hBN. Modulation in the MHz range superimposed on the Hahn-echo decay curve are shown to be induced by coherent coupling of the VB- spin with the three nearest 14N nuclei through a nuclear quadrupole interaction of 2.11 MHz. Supporting DFT calculation confirm that the electron-nuclear coupling is confined to the defective layer. Our findings allow an in-depth understanding of the electron-nuclear interactions of the VB- defect in hBN and demonstrate its strong potential in quantum technologies.