Extending and measuring dephasing times of nuclear spins in NV centers of diamond

Long coherence times rank among the most important performance measures for many different types of quantum technology. In NV centers of diamond, the nuclear spins provide particularly long dephasing times. However, since initialization and readout require assistance from the electron spin, the apparent dephasing times can be reduced by the electron spin lifetime. Here we propose and implement schemes for measuring and extending the dephasing times of nuclear spins, resulting in dephasing times that are longer than the longitudinal relaxation time $T_1$ of the electron spin.