Low temperature photo-physics of single NV centers in diamond

TL;DR

This study explores how magnetic fields at cryogenic temperatures affect the photoluminescence of individual NV centers in diamond, revealing insights into their excited states, strain effects, and quantum sensing potential.

Contribution

It provides new understanding of NV center excited state structure and introduces a method to characterize strain effects and charge dynamics at low temperatures.

Findings

Photoluminescence dips at specific magnetic fields indicate excited state anti-crossings.

Strain influences the NV centers' excited state energy levels.

Results impact the use of NV centers in low-temperature quantum sensing.

Abstract

We investigate the magnetic field dependent photo-physics of individual Nitrogen-Vacancy (NV) color centers in diamond under cryogenic conditions. At distinct magnetic fields, we observe significant reductions in the NV photoluminescence rate, which indicate a marked decrease in the optical readout efficiency of the NV's ground state spin. We assign these dips to excited state level anti-crossings, which occur at magnetic fields that strongly depend on the effective, local strain environment of the NV center. Our results offer new insights into the structure of the NVs' excited states and a new tool for their effective characterization. Using this tool, we observe strong indications for strain-dependent variations of the NV's orbital g-factor, obtain new insights into NV charge state dynamics, and draw important conclusions regarding the applicability of NV centers for low-temperature quantum sensing.