High-Contrast Two-Frequency Optically Detected Resonances in Diamond Nitrogen-Vacancy Centers for Timekeeping Schemes

摘要

Negatively charged nitrogen-vacancy (NV) centers are widely used in a precision metrology due to their unique properties, which allow spin states to be controlled at relatively high temperatures. The NV-centers are most widely used in magnetometry of ultrahigh spatial resolution, because the frequencies of the resonances in their optically detected spectra are magnetically dependent; however, over the past several years, new works have been published on the use of NV centers in a time metrology as well. The effectiveness of NV centers being used in this case is limited due to the strong dependence of the parameters of the centers' energy structure on the magnetic field, temperature, and pressure; nevertheless, their use as microdimensional microwave range frequency references remains very promising. In particular, zero-field level anticrossing can be used to suppress the sensitivity of narrow resonances to magnetic fields for metrological applications. In this letter, we present a method of two-frequency excitation of narrow magnetically independent optically detected resonances in bulk NV diamond in a zero magnetic field, and discuss the possibility of their use in timekeeping schemes.