A compact radiofrequency spectrum analyzer based on nitrogen-vacancy centers in diamond

We have realized a compact radiofrequency spectrum analyzer based on nitrogen-vacancy (NV) color centers in diamond. The RF spectral components are spatially encoded by means of a Zeeman shift of the NV resonances induced by a magnetic field gradient. The fluorescence of the NV centers is imaged on a CMOS detector array using a gradient index lens. The spectral components of the signal are revealed by the appearance of dark lines in the image. We observed frequencies up to 10 GHz, with a resolution of a few MHz and a RF sensitivity of the order of 100 µW.