Nitrogen-vacancy color centers (NVs) in diamond can be measured at the single cite level even at room temperature, allowing to perform a variety of fundamental experiments.
Here the recent progress in controlling small nuclear spin ensembles at ambient conditions will be presented. A Dynamic Nuclear spin Polarization (DNP) method was developed to transfer the NV’s high (> 92 %) electron spin polarization induced by short laser pulses to the surrounding 13C carbon nuclear spins (I = 1/2). Here the NV is repeatedly repolarized optically, thus providing an effectively infinite polarization reservoir. The polarisation of the nuclear spin ensemble was so high, that it lead to narrowing of the line width of a single NV electron spin transition by a factor of eight . The same technique was used to polarize a macroscopic ensemble of 13C spins, where we achieved an increase of the NMR signal by a factor of 45 . A novel method for both polarization of the nuclear spin bath and its quantitative measurement will be demonstrated - Polarization Read Out by Polarization Inversion (PROPI) . With this technique we are able to determine the exact number of spin quanta transferred from the NV’s electron spin to the nuclear spin bath. Finally, NMR spectroscopy of few tens of nuclear spins is demonstrated by using radio frequency pulses for coherent control and PROPI for polarization and readout of the spin ensemble .
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