Magnetic field-induced enhancement of the nitrogen-vacancy fluorescence quantum yield

TL;DR

This study demonstrates that applying an external magnetic field can enhance the fluorescence quantum yield of nitrogen-vacancy centers in diamond, providing insights into their photophysical behavior and potential for improved magnetometry.

Contribution

We experimentally observed a magnetic field-induced increase in NV fluorescence quantum yield and developed a phenomenological model explaining this effect.

Findings

Quantum yield increased by up to 7% with magnetic field

Phenomenological model agrees with experimental data at low excitation

Results advance understanding of NV center photophysics

Abstract

The nitrogen-vacancy (NV) centre in diamond is a unique optical defect that is used in many applications today and methods to enhance its fluorescence brightness are highly sought after. We observed experimentally an enhancement of the NV quantum yield by up to 7% in bulk diamond caused by an external magnetic field relative to the field-free case. This observation is rationalised phenomenologically in terms of a magnetic field dependence of the NV excited state triplet-to-singlet transition rate. The theoretical model is in good qualitative agreement with the experimental results at low excitation intensities. Our results significantly contribute to our fundamental understanding of the photophysical properties of the NV defect in diamond and may enable novel NV centre-based magnetometry techniques.