Demonstration of highly sensitive wideband microwave sensing using ensemble nitrogen-vacancy centers

Abstract

Microwave magnetometry is essential for the advancement of microwave technologies. We demonstrate a broadband microwave sensing protocol using the AC Zeeman effect with ensemble nitrogen-vacancy (NV) centers in diamond. A widefield microscope can visualize the frequency characteristics of the microwave resonator and the spatial distribution of off-resonant microwave amplitude. Furthermore, by combining this method with dynamical decoupling, we achieve the microwave amplitude sensitivity of 5.2 μT/Hz, which is 7.7 times better than 40.2 μT/Hz obtained using the protocol in previous research over a sensing volume of 2.77 μm×2.77 μm×30  nm. Our achievement is a concrete step in adapting ensemble NV centers for wideband and widefield microwave imaging.