Nitrogen vacancy (NV) center spins in diamond are attractive candidates for quantum information processing and sensitive, nanoscale magnetometers due to their long spin coherence times under ambient conditions . The ground state of the NV spin is also sensitive to electric fields . We present a theory of quantum detection using positive operator valued measurements (POVMs) wherein the presence of an electric field is determined by spin-dependent fluorescence of an NV center. The predicted sensitivity to small electric fields can also be used for photon detection. Photons incident upon a chromophore near the diamond interface may induce a charge polarization and electric dipole moment of several Debye [3, 4]. The measured readout state from the NV center predicts the existence of the photo-excited electric dipole field and, by extension, the incident photon. We describe a measurement protocol by which the time of the incident photon can be resolved. We discuss the role of magnetic fields and multiple NV centers in reducing the error rate of measurement.
This work was supported by DARPA DETECT.
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