Quantum control of the tin-vacancy spin qubit in diamond

TL;DR

This paper demonstrates multi-axis all-optical control of the tin-vacancy (SnV) spin qubit in diamond, achieving long coherence times and showing its potential for quantum networking applications.

Contribution

It introduces a method for all-optical coherent control of the SnV spin qubit and reports significant improvements in coherence times, advancing its use in quantum networks.

Findings

Achieved spin Rabi oscillations at 3.6 MHz

Extended spin coherence time to 0.33 ms with dynamical decoupling

Confirmed coherent control at 1.7 K

Abstract

Group-IV color centers in diamond are a promising light-matter interface for quantum networking devices. The negatively charged tin-vacancy center (SnV) is particularly interesting, as its large spin-orbit coupling offers strong protection against phonon dephasing and robust cyclicity of its optical transitions towards spin-photon entanglement schemes. Here, we demonstrate multi-axis coherent control of the SnV spin qubit via an all-optical stimulated Raman drive between the ground and excited states. We use coherent population trapping and optically driven electronic spin resonance to confirm coherent access to the qubit at 1.7 K, and obtain spin Rabi oscillations at a rate of $\Omega/2\pi$=3.6(1) MHz. All-optical Ramsey interferometry reveals a spin dephasing time of $T_2^*$=1.3(3)$\mu$s and two-pulse dynamical decoupling already extends the spin coherence time to $T_2$=0.33(14) ms. Combined with transform-limited photons and integration into photonic nanostructures, our results make the SnV a competitive spin-photon building block for quantum networks.