All-optical formation of coherent dark states of silicon-vacancy spins in diamond

TL;DR

This paper demonstrates all-optical coherent control of silicon-vacancy spins in diamond, achieving spin superpositions and coherence times over 250 nanoseconds at 4 K, advancing quantum technology applications.

Contribution

It introduces a method for all-optical generation of coherent spin superpositions in silicon-vacancy centers, highlighting their potential for quantum information processing.

Findings

Spin coherence time T2* exceeds 250 ns at 4 K

All-optical control of silicon-vacancy spins demonstrated

Phonon-mediated coupling affects decoherence

Abstract

Spin impurities in diamond can be versatile tools for a wide range of solid-state-based quantum technologies, but finding spin impurities which offer sufficient quality in both photonic and spin properties remains a challenge for this pursuit. The silicon-vacancy center has recently attracted a lot of interest due to its spin-accessible optical transitions and the quality of its optical spectrum. Complementing these properties, spin coherence is essential for the suitability of this center as a spin-photon quantum interface. Here, we report all-optical generation of coherent superpositions of spin states in the ground state of a negatively charged silicon-vacancy center using coherent population trapping. Our measurements reveal a characteristic spin coherence time, T2*, exceeding 250 nanoseconds at 4 K. We further investigate the role of phonon-mediated coupling between orbital states as a source of irreversible decoherence. Our results indicate the feasibility of all-optical coherent control of silicon-vacancy spins using ultrafast laser pulses.