Microwave Resonator Readout of an Ensemble Solid State Spin Sensor

Abstract

Microwave resonator readout of the cavity-spin interaction between a spin defect center ensemble and a microwave resonator yields fidelities that are orders of magnitude higher than is possible with optical readouts. In microwave resonator readout, microwave photons probe a microwave resonator coupled to a spin defect center ensemble subjected to a physical parameter to be measured. The physical parameter shifts the spin defect centers' resonances, which in turn change the dispersion and/or absorption of the microwave resonator. The microwave photons probe these dispersion and/or absorption changes, yielding a measurement with higher visibility, lower shot noise, better sensitivity, and higher signal-to-noise ratio than a comparable fluorescence measurement. In addition, microwave resonator readout enables coherent averaging of spin defect center ensembles and is compatible with spin systems other than nitrogen vacancies in diamond.

1 . A sensor system comprising:
 a microwave resonator;   a solid-state host electromagnetically coupled to the microwave resonator and containing spin defect centers;   a microwave radiation source, in electromagnetic communication with the microwave resonator and the spin defect centers, to apply microwave radiation to the microwave resonator and the spin defect centers, the microwave resonator enhancing the interaction between the microwave radiation and the spin defect centers; and   a detector, in electromagnetic communication with the microwave resonator and the spin defect centers, to measure an amplitude and/or a phase of the microwave radiation exiting the microwave resonator after interacting with the spin defect centers.