Extended spin relaxation times of optically addressed telecom defects in silicon carbide

TL;DR

This paper demonstrates that vanadium defects in silicon carbide exhibit significantly extended spin relaxation times at low temperatures, highlighting their potential for scalable quantum communication applications.

Contribution

The study introduces a method to optically measure and extend spin relaxation times of V4+ defects in SiC, revealing site-specific T1 times up to over 27 seconds and identifying relaxation mechanisms.

Findings

Spin relaxation times increase four orders of magnitude from 57 ms to over 27 s at low temperatures.

Efficient optical spin polarization and readout enable temperature-dependent T1 measurements.

Relaxation involves a two-phonon Orbach process, suggesting strain-tuning possibilities.

Abstract

Optically interfaced solid-state defects are promising candidates for quantum communication technologies. The ideal defect system would feature bright telecom emission, long-lived spin states, and a scalable material platform, simultaneously. Here, we employ one such system, vanadium (V4+) in silicon carbide (SiC), to establish a potential telecom spin-photon interface within a mature semiconductor host. This demonstration of efficient optical spin polarization and readout facilitates all optical measurements of temperature-dependent spin relaxation times (T1). With this technique, we lower the temperature from about 2K to 100 mK to observe a remarkable four-orders-of-magnitude increase in spin T1 from all measured sites, with site-specific values ranging from 57 ms to above 27 s. Furthermore, we identify the underlying relaxation mechanisms, which involve a two-phonon Orbach process, indicating the opportunity for strain-tuning to enable qubit operation at higher temperatures. These results position V4+ in SiC as a prime candidate for scalable quantum nodes in future quantum networks.