Robust external spin hyperpolarization of quadrupolar nuclei enabled by strain

TL;DR

This theoretical study proposes a strain-enabled method for robust external hyperpolarization of quadrupolar nuclei near diamond surfaces, enhancing spin polarization transfer in nanomaterials for quantum and biomedical applications.

Contribution

It introduces a novel polarization transfer mechanism leveraging crystal strain to achieve robust hyperpolarization of quadrupolar nuclei near diamond surfaces.

Findings

Polarization transfer is robust against NV orientation and strain inhomogeneity.

Strain facilitates polarization transfer across level anticrossings.

Potential for hyperpolarizing spins in nanomaterials and quantum simulators.

Abstract

In a theoretical study, we investigate the spin dynamics of interacting nitrogen-vacancy (NV) centers and quadrupolar I = 3/2 nuclear spins, specifically 11B spins in hexagonal boron nitride (h-BN) nanosheets located near the microdiamond surface. We demonstrate the possibility of obtaining external spin-polarization by magnetic-field sweeps across the level anticrossings around zero-field. To achieve this, we leverage crystal strains to establish a polarization transfer mechanism that remains robust against variations in NV orientation, crystal strain inhomogeneity, and electron-nuclear effective couplings. These results pave the way for hyperpolarization of spins in nanomaterials near the diamond surface without experiencing polarization loss to intrinsic nuclear spin-1/2 species, such as 13C and 1H nuclear spins in diamond. The 11B spins in h-BN nanosheets, with their extended relaxation time and large surface area, present a promising alternative for relayed nuclear polarization to the liquid phase and for the development of quantum simulators based on surface nuclear spins.