Cavity-enhanced measurements of defect spins in silicon carbide

TL;DR

This paper demonstrates how silicon carbide photonic crystal cavities can significantly enhance the optical signals and spin initialization rates of defect qubits, advancing quantum information and sensing technologies.

Contribution

It introduces the use of 3C silicon carbide photonic crystal cavities to improve excitation and detection of defect spins, enabling better control and study of qubit ensembles.

Findings

Up to 30-fold increase in photoluminescence signals.

Approximately twofold increase in spin initialization rates.

Ability to study inhomogeneous broadening in defect ensembles.

Abstract

The identification of new solid-state defect qubit candidates in widely used semiconductors has the potential to enable the use of nanofabricated devices for enhanced qubit measurement and control operations. In particular, the recent discovery of optically active spin states in silicon carbide thin films offers a scalable route for incorporating defect qubits into on-chip photonic devices. Here we demonstrate the use of 3C silicon carbide photonic crystal cavities for enhanced excitation of color center defect spin ensembles in order to increase measured photoluminescence signal count rates, optically detected magnetic resonance signal intensities, and optical spin initialization rates. We observe up to a factor of 30 increase in the photoluminescence and ODMR signals from Ky5 color centers excited by cavity resonant excitation and increase the rate of ground-state spin initialization by approximately a factor of two. Furthermore, we show that the small excitation mode volume and enhanced excitation and collection efficiencies provided by the structures can be used to study inhomogeneous broadening in defect qubit ensembles. These results highlight some of the benefits that nanofabricated devices offer for engineering the local photonic environment of color center defect qubits to enable applications in quantum information and sensing.