  Nitrogen-Vacancy (NV) centers in diamonds provide a room-temperature platform
for various emerging quantum technologies, e.g. the long nuclear spin coherence
times as potential quantum memory registers. We demonstrate a freezing protocol
for an NV center to isolate its intrinsic nuclear spin from a noisy
electromagnetic environment. Any initial state of the nuclear spin can be
frozen when the hyperfine-coupled electron and nuclear spins are simultaneously
driven with unequal Rabi frequencies. Through numerical simulations, we show
that our protocol can effectively shield the nuclear spin from strong drive or
noise fields. We also observe a clear suppression of quantum correlations in
the frozen nuclear spin regime by measuring the quantum discord of the
electron-nuclear spin system. These features can be instrumental in extending
the storage times of NV nuclear-spin based quantum memories in hybrid quantum
systems.
