Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance (NMR) as a result of the small nuclear magnetic moment. We demonstrate a fast ~ 500 ns nuclear spin phase gate on a 14N nuclear spin qubit intrinsic to a nitrogen-vacancy (NV) center in diamond. The phase gate is enabled by the hyperfine interaction and off-resonance driving of electron spin transitions. Repeated applications of the phase gate bang-bang decouple the nuclear spin from the environment, locking the spin state for up to ~ 140 microseconds.
@article{arxiv.1403.3311,
title = {Fast Room-Temperature Phase Gate on a Single Nuclear Spin in Diamond},
author = {S. Sangtawesin and T. O. Brundage and J. R. Petta},
journal= {arXiv preprint arXiv:1403.3311},
year = {2014}
}