Designing defect-based qubit candidates in wide-gap binary semiconductors for solid-state quantum technologies

TL;DR

This paper proposes using large metal ion-vacancy complexes in wide-gap binary semiconductors like 4H-SiC and w-AlN as promising solid-state qubit candidates, supported by first-principles calculations of their properties.

Contribution

It introduces a novel defect design approach for qubits in wide-gap semiconductors, focusing on heavy metal ion-vacancy complexes with favorable electronic and spin properties.

Findings

Neutral Hf- and Zr-vacancy complexes are energetically favorable.

These defects have spin-triplet ground states similar to known qubits.

Predicted optical and hyperfine parameters support experimental identification.

Abstract

The development of novel quantum bits is key to extend the scope of solid-state quantum information science and technology. Using first-principles calculations, we propose that large metal ion - vacancy complexes are promising qubit candidates in two binary crystals: 4H-SiC and w-AlN. In particular, we found that the formation of neutral Hf- and Zr-vacancy complexes is energetically favorable in both solids; these defects have spin-triplet ground states, with electronic structures similar to those of the diamond NV center and the SiC di-vacancy. Interestingly, they exhibit different spin-strain coupling characteristics, and the nature of heavy metal ions may allow for easy defect implantation in desired lattice locations and ensure stability against defect diffusion. In order to support future experimental identification of the proposed defects, we report predictions of their optical zero-phonon line, zero-field splitting and hyperfine parameters. The defect design concept identified here may be generalized to other binary semiconductors to facilitate the exploration of new solid-state qubits.