Optical hyerpolarization in nanodiamonds: towards quantum-enhanced NMR/MRI

Atom-like defect center spins in wide bandgap materials, such as Nitrogen Vacancy (NV) center spins in diamond, are compelling platforms for the optical dynamic nuclear polarization (DNP) of nuclear spins. NV electronic spins can be optically polarized at room temperature, and this polarization potentially transferred to external nuclei to hyperpolarize them to levels far in excess of Boltzmann levels. Nanodiamond powder is particularly attractive in this quest: they have large surface areas (>7m²/g for 100nm particles), and one could arrange for a close physical contact between the polarized NVs and external nuclear spins.

In this work, we produce "optically hyperpolarized nanodiamonds", obtaining high bulk ¹³C polarization (~1%) [1]. We develope a remarkably simple, low-field optical DNP technique that proves to be fully orientation independent [2]. Our technique also allows simple control of the hyperpolarization direction, that only depends on the direction of microwave sweeps across the electron spectrum. This paves for quantum-assisted classical NMR and MRI, allowing for vastly accelerated spectroscopy and imaging with chemical specificity.

1. A. Ajoy, et al. Science Advances, 4, eaar5492 (2018).
2. A. Ajoy, et al. PNAS 1807125115, (2018).