Identifying electronic transitions of defects in hexagonal boron nitride for quantum memories

TL;DR

This paper investigates defects in hexagonal boron nitride for quantum memory applications, analyzing electronic transitions and properties to identify suitable defect states for efficient, long-lasting quantum storage and sensing.

Contribution

It introduces a theoretical model and density functional theory calculations to identify specific defects in hBN with desirable properties for quantum memory and sensing.

Findings

Identified defects with $$ electronic structures suitable for Raman-type quantum memory

Analyzed the quality factor and bandwidth requirements for high writing efficiency

Suggested potential for quantum sensing through triplet-singlet spin states

Abstract

A quantum memory is a crucial keystone for enabling large-scale quantum networks. Applicable to the practical implementation, specific properties, i.e., long storage time, selective efficient coupling with other systems, and a high memory efficiency are desirable. Though many quantum memory systems are developed thus far, none of them can perfectly meet all requirements. This work herein proposes a quantum memory based on color centers in hexagonal boron nitride (hBN), where its performance is evaluated based on a simple theoretical model of suitable defects in a cavity. Employing density functional theory calculations, 257 triplet and 211 singlet spin electronic transitions are investigated. Among these defects, it is found that some defects inherit the $\Lambda$ electronic structures desirable for a Raman-type quantum memory and optical transitions can couple with other quantum systems. Further, the required quality factor and bandwidth are examined for each defect to achieve a 95% writing efficiency. Both parameters are influenced by the radiative transition rate in the defect state. In addition, inheriting triplet-singlet spin multiplicity indicates the possibility of being a quantum sensing, in particular, optically detected magnetic resonance. This work therefore demonstrates the potential usage of hBN defects as a quantum memory in future quantum networks.