Temperature dependent single- and double-quantum relaxation of negatively charged boron vacancies in hexagonal boron nitride

TL;DR

This study investigates how temperature affects single- and double-quantum relaxation rates of negatively charged boron vacancies in hexagonal boron nitride, revealing increased relaxation rates at higher temperatures and the dominance of double-quantum relaxation above 400 K.

Contribution

It provides the first detailed analysis of temperature-dependent quantum relaxation mechanisms in boron vacancies, highlighting the role of higher-energy phonons in decoherence.

Findings

Relaxation rates increase with temperature.

Double-quantum relaxation dominates above 400 K.

High-temperature relaxation linked to higher-energy phonons.

Abstract

The negatively charged boron vacancy in two-dimensional hexagonal boron nitride has emerged as a promising candidate for quantum sensing. The coherence time of this defect spins which coherent quantum sensing resides in is limited spin-phonon interactions, while the underlying physical mechanism of the corresponding high-temperature behavior is still not fully understood. Here, we probe the single- and double-quantum relaxation rates on this center over the temperature range from 293 to 393 K. The results show that both relaxation rates increase with increasing temperature, and the double-quantum relaxation rate significantly increases rapidly. At high temperature (above 400 K), the double-quantum relaxation rate is much greater than single-quantum relaxation rate, and may dominate the decoherence channel of spin-phonon interactions. Using a theoretical model of second-order spin-phonon interactions, we attribute the high-temperature spin relaxation rates to interactions with higher-energy effective phonon mode, aiding the further understanding and guiding high-temperature sensing applications.