Title: Microelectronic readout of a diamond quantum sensor

Abstract: Quantum sensors based on the nitrogen-vacancy (NV) centre in diamond are rapidly advancing from scientific exploration towards the first generation of commercial applications. While significant progress has been made in developing suitable methods for the manipulation of the NV centre spin state, the detection of the defect luminescence has so far limited the performance of miniaturized sensor architectures. The recent development of photoelectric detection of the NV centre's spin state offers a path to circumvent these limitations, but has to-date required research-grade low current amplifiers to detect the picoampere-scale currents obtained from these systems. Here we report on the photoelectric detection of magnetic resonance (PDMR) with NV ensembles using a complementary metal-oxide semiconductor (CMOS) device. The integrated circuit delivers a digitized output of the diamond sensor with low noise and 50 femtoampere resolution. This integration provides the last missing component on the path to a compact, diamond-based quantum sensor. The device is suited for continuous wave (CW) as well as pulsed operation. We demonstrate its functionality with DC and AC magnetometry up to several megahertz, coherent spin rotation and multi-axial decoupling sequences for quantum sensing.