A defect in diamond with millisecond-scale spin relaxation time at room temperature

TL;DR

This paper reports the discovery and characterization of the WAR5 defect in diamond, which exhibits millisecond-scale spin relaxation times at room temperature, surpassing previously known solid-state defects.

Contribution

It introduces the WAR5 defect as a new solid-state spin defect with exceptionally long $T_1$ times at room temperature and demonstrates its optical polarization capabilities.

Findings

$T_1$ of 0.97 ms at room temperature

$T_2$ of 246 μs extendable to 6.49 ms at 4 K

Optical spin polarization across 405-500 nm wavelengths

Abstract

Spin defects in diamond are promising platforms for quantum sensing. The longest electron spin relaxation times ($T_1$) at room temperature for solid-state defects are observed in nitrogen vacancy centers in diamond, which can reach 6.67 ms, and substitutional nitrogen ("P1 centers") in diamond, which exhibit a $T_1$ of 2 ms. No other solid-state defect has exhibited millisecond-scale spin relaxation times at room temperature thus far. Here, we characterize the spin properties of the WAR5 defect in diamond with pulsed electron spin resonance. The observed $T_1$ is one of the longest for solid-state spin defects: 0.97(27) ms at room temperature and 14.38(19) min at 4 K. The observed coherence time ($T_2$) is 246(7) $\mu$s, which can be extended to 6.49(34) ms at 4 K with dynamical decoupling. Furthermore, we demonstrate optical spin polarization with a range of wavelengths from 405 nm to 500 nm and propose potential zero-phonon line candidates.