Fig. 2
Repetitive readout of a nuclear-spin memory in a nanodiamond. a Repetitive readout characterization protocol. After the nuclear spin is initialized (protocol not shown), the electronic spin is prepared in either |0〉e or |−1〉e via the MWB transition and the electronic-spin state is stored in the nuclear spin by a CNOT gate composed of two radio frequency (RF) pulses. Finally, the nuclear-spin state is repetitively readout N times. b Readout fidelity of the repetitive readout protocol at B0 = 244 mT. Error bars denoting standard error are smaller than the data markers. Inset: difference in number of counts per measurement C0 (preparation in |0〉e) and C1 (preparation in |−1〉e) for different numbers of readout cycles N
