Deep Spin Defects in Zinc Oxide for High-Fidelity Single-Shot Readout

TL;DR

This paper predicts a new deep-level spin defect in zinc oxide, the Mo_Zn-V_O complex, which exhibits promising properties for high-fidelity quantum bit applications, including long coherence times and optical addressability.

Contribution

First-principles calculations identify Mo_Zn-V_O as a robust, optically addressable spin qubit in ZnO with favorable coherence and readout properties.

Findings

Mo_Zn-V_O exhibits a spin-triplet ground state.

It has visible-range optical transitions with high quantum yield.

Long spin coherence times (~4 ms) are predicted.

Abstract

Wide-bandgap oxides such as ZnO are favorable hosts for spin defect qubits due to their dilute nuclear spin background and potential for ultra-high purity. Yet, a deep-level defect qubit with robust optical and spin properties has not been identified in this material. Here, using first-principles calculations, we predict that the molybdenum-vacancy complex, Mo_Zn-V_O, exhibits the essential characteristics of an optically addressable spin qubit: a spin-triplet ground state, visible-range optical transitions with high quantum yield, and an unusually small Huang-Rhys factor (~5, compared to 10-30 in known ZnO defects). We further find long spin coherence times (T_2 ~ 4 ms) when both nuclear and impurity spin baths are considered, with paramagnetic impurities setting a threshold concentration of 0.035 ppm. Importantly, the combination of strong spin-orbit coupling and the absence of Jahn-Teller distortion supports spin-selective intersystem crossing and high-fidelity single-shot readout at elevated temperatures and across wide magnetic field ranges. By identifying ZnO as a host for deep-level defect qubits, our work points toward a pathway to scalable, integrable oxide-based quantum technologies and broadens the material foundation for solid-state quantum information science.