  Although a nuclear spin is weakly coupled to its environment, due to its
small gyromagnetic ratio, its coherence time is limited by the hyperfine
coupling to a nearby noisy electron. Here, we propose to utilize continuous
dynamical decoupling to refocus the coupling to the electron. If the random
phase accumulated by the nuclear spin through the reduced coupling terms is
sufficient small, we can increase the nuclear coherence time. Initially, we
demonstrate this on a simple case with a two-level electron spin, while taking
all relevant hyperfine coupling terms and noise terms into account. We then
extend the analysis to a nitrogen-vacancy center in diamond having a three
level structure.

Quantum Physics