Locking of electron spin coherence over fifty milliseconds in natural silicon carbide

TL;DR

This paper demonstrates that silicon vacancies in natural silicon carbide can maintain electron spin coherence for nearly 0.1 seconds by suppressing decoherence mechanisms, advancing quantum memory potential.

Contribution

It introduces a method to significantly extend spin coherence times in natural SiC using magnetic fields and dynamic decoupling, revealing new pathways for quantum memory development.

Findings

Spin coherence approaches 0.1 seconds at cryogenic temperatures.

Decoherence is reduced by suppressing heteronuclear spin interactions.

Long coherence times are limited by phonon-assisted relaxation mechanisms.

Abstract

We demonstrate that silicon carbide (SiC) with natural isotope abundance can preserve a coherent spin superposition in silicon vacancies over unexpectedly long time approaching 0.1 seconds. The spin-locked subspace with drastically reduced decoherence rate is attained through the suppression of heteronuclear spin cross-talking by applying a moderate magnetic field in combination with dynamic decoupling from the nuclear spin baths. We identify several phonon-assisted mechanisms of spin-lattice relaxation, ultimately limiting quantum coherence, and find that it can be extremely long at cryogenic temperature, equal or even longer than 8 seconds. Our approach may be extended to other polyatomic compounds and open a path towards improved qubit memory for wafer-scale quantum techmologies.