# Optical charge state control of spin defects in 4H-SiC

## TL;DR

This paper demonstrates bidirectional optical control of charge states in silicon carbide defects, significantly enhancing photoluminescence and enabling stable, long-term charge state manipulation for quantum technology applications.

## Contribution

It introduces a method for optical charge state control of divacancy and silicon vacancy defects in 4H-SiC, with stable, hours-long charge state persistence and a comprehensive defect model.

## Key findings

- Up to three orders of magnitude increase in photoluminescence with near-UV excitation
- Stable charge state control for hours at cryogenic temperatures
- Bidirectional optical charge conversion between bright and dark states

## Abstract

Defects in silicon carbide (SiC) have emerged as a favorable platform for optically-active spin-based quantum technologies. Spin qubits exist in specific charge states of these defects, where the ability to control these states can provide enhanced spin-dependent readout and long-term charge stability of the qubits. We investigate this charge state control for two major spin qubits in 4H-SiC, the divacancy (VV) and silicon vacancy (Vsi), obtaining bidirectional optical charge conversion between the bright and dark states of these defects. We measure increased photoluminescence from VV ensembles by up to three orders of magnitude using near-ultraviolet excitation, depending on the substrate, and without degrading the electron spin coherence time. This charge conversion remains stable for hours at cryogenic temperatures, allowing spatial and persistent patterning of the relative charge state populations. We develop a comprehensive model of the defects and optical processes involved, offering a strong basis to improve material design and to develop quantum applications in SiC.