Polarizing nuclear spins is of fundamental importance in biology, chemistry and physics. Methods for hyperpolarizing 13C nuclei from free electrons in bulk, usually demand operation at cryogenic temperatures. Room-temperature approaches targeting diamonds with nitrogen-vacancy (NV) centers could alleviate this need, but hitherto proposed strategies lack generality as they demand stringent conditions on the strength and/or alignment of the magnetic field. We report here an approach for achieving efficient electron->13C spin alignment transfers, compatible with a broad range of magnetic field strengths and field orientations with respect to the diamond crystal. This versatility results from combining coherent microwave- and incoherent laser-induced transitions between selected energy states of the coupled electron-nuclear spin manifold. 13C-detected Nuclear Magnetic Resonance (NMR) experiments demonstrate that this hyperpolarization can be transferred via first-shell or via distant 13Cs, throughout the nuclear bulk ensemble. This method opens new perspectives for applications of diamond NV centers in NMR, and in quantum information processing.
@article{arxiv.1412.8635,
title = {Local and bulk 13C hyperpolarization in NV-centered diamonds at variable fields and orientations},
author = {Gonzalo A. Alvarez and Christian O. Bretschneider and Ran Fischer and Paz London and Hisao Kanda and Shinobu Onoda and Junichi Isoya and David Gershoni and Lucio Frydman},
journal= {arXiv preprint arXiv:1412.8635},
year = {2015}
}