Low field nuclear polarization using Nitrogen Vacancy centers in diamonds

TL;DR

This paper introduces a new low-field nuclear polarization technique using Nitrogen Vacancy centers in diamonds, which is more practical and robust than previous high-field methods, demonstrated through numerical simulations.

Contribution

The paper presents the refocused NOVEL sequence enabling polarization transfer at low magnetic fields, overcoming alignment challenges of prior high-field methods.

Findings

Refocused NOVEL outperforms traditional NOVEL in simulations.

Effective polarization transfer at low magnetic fields.

Robustness against magnetic field misalignment.

Abstract

It was recently demonstrated that bulk nuclear polarization can be obtained using Nitrogen Vacancy (NV) color centers in diamonds, even at ambient conditions. This is based on the optical polarization of the NV electron spin, and using several polarization transfer methods. One such method is the NOVEL sequence, where a spin-locked sequence is applied on the NV spin, with a microwave power equal to the nuclear precession frequency. This was performed at relatively high fields, to allow for both polarization transfer and noise decoupling. As a result, this scheme requires accurate magnetic field alignment in order preserve the NV properties. Such a requirement may be undesired or impractical in many practical scenareios. Here we present a new sequence, termed the refocused NOVEL, which can be used for polarization transfer (and detection) even at low fields. Numerical simulations are performed, taking into account both the spin Hamiltonian and spin-decoherence, and we show that, under realistic parameters, it can outperform the NOVEL sequence.