Effect of inter-system crossing rates and optical illumination on the polarization of nuclear spins nearby nitrogen-vacancy centers

TL;DR

This paper investigates how inter-system crossing rates and optical illumination influence nuclear spin polarization near NV centers, highlighting the dependence on excitation power and transition rate models for quantum applications.

Contribution

It analyzes the impact of different inter-system crossing rate models on nuclear polarization methods near NV centers, considering optical power and nuclear position effects.

Findings

Nuclear polarization varies with optical excitation power.

Different transition rate models yield different polarization degrees.

Performance depends on nuclear position relative to NV center axis.

Abstract

Several efforts have been made to polarize the nearby nuclear environment of nitrogen vacancy (NV) centers for quantum metrology and quantum information applications. Different methods showed different nuclear spin polarization efficiencies and rely on electronic spin polarization associated to the NV center, which in turn crucially depends on the inter-system crossing. Recently, the rates involved in the inter-system crossing have been measured leading to different transition rate models. Here, we consider the effect of these rates on several nuclear polarization methods based on the level anti-crossing, and precession of the nuclear population while the electronic spin is in the ms = 0 and ms = 1 spin states. We show that the nuclear polarization depends on the power of optical excitation used to polarize the electronic spin. The degree of nuclear spin polarization is different for each transition rate model. Therefore, the results presented here are relevant for validating these models and for polarizing nuclear spins. Furthermore, we analyze the performance of each method by considering the nuclear position relative to the symmetry axis of the NV center.