Strongly polarizing weakly coupled ¹³C nuclear spins with optically pumped nitrogen-vacancy center

Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has attracted widespread attention recently due to its various applications. Here we present an analytical theory and comprehensive understanding on how to optimize the dynamic nuclear polarization by an optically pumped NV center near the ground state level anticrossing. Our results not only provide a parameter-free explanation and a clearly physics picture for the recently observed polarization dependence on the magnetic field for strongly coupled ¹³C nuclei \[H. J. Wang et al., Nat. Commun. 4, 1 (2013)\], but also demonstrate the possibility to strongly polarize weakly coupled ¹³C nuclei under weak optical pumping and suitably chosen magnetic field. This allows sensitive magnetic control of the ¹³C nuclear spin polarization for NMR applications and significant suppression of the ¹³C nuclear spin noise to prolong the NV spin coherence time.