Coherence of a charge stabilised tin-vacancy spin in diamond

TL;DR

This paper investigates the charge stability and coherence properties of tin-vacancy centers in diamond, demonstrating efficient charge state initialization, long spin coherence times, and single-shot spin readout for quantum information applications.

Contribution

It reveals the charge cycle of G4V centers and demonstrates highly efficient charge state initialization and spin coherence measurements in SnV centers.

Findings

Achieved stable optical resonances of SnV centers

Measured a spin dephasing time of 5 microseconds

Demonstrated single-shot spin state readout without magnetic field

Abstract

Quantum information processing (QIP) with solid state spin qubits strongly depends on the efficient initialisation of the qubit's desired charge state. While the negatively charged tin-vacancy ($\text{SnV}^{-}$) centre in diamond has emerged as an excellent platform for realising QIP protocols due to long spin coherence times at liquid helium temperature and lifetime limited optical transitions, its usefulness is severely limited by termination of the fluorescence under resonant excitation [1,2,3]. Here, we unveil the underlying charge cycle of group IV-vacancy (G4V) centres and exploit it to demonstrate highly efficient initialisation of the desired negative charge state of single SnV centres while preserving long term stable optical resonances. We furthermore all-optically probe the coherence of the ground state spins by means of coherent population trapping and find a spin dephasing time of 5$\mu$s. Additionally, we demonstrate proof-of-principle single shot spin state readout without the necessity of a magnetic field aligned to the symmetry axis of the defect.