Cavity quantum electrodynamic readout of a solid-state spin sensor

Abstract

Robust, high-fidelity readout is central to quantum device performance. Overcoming poor readout is an increasingly urgent challenge for devices based on solid-state spin defects, particularly given their rapid adoption in quantum sensing, quantum information, and tests of fundamental physics. Spin defects in solids combine the repeatability and precision available to atomic and cryogenic systems with substantial advantages in compactness and range of operating conditions. However, in spite of experimental progress in specific systems, solid-state spin sensors still lack a universal, high-fidelity readout technique. Here we demonstrate high-fidelity, room-temperature readout of an ensemble of nitrogen-vacancy (NV) centers via strong coupling to a dielectric microwave cavity, building on similar techniques commonly applied in cryogenic circuit cavity quantum electrodynamics. This strong collective interaction allows the spin ensemble's microwave transition to be probed directly, thereby overcoming the optical photon shot noise limitations of conventional fluorescence readout. Applying this technique to magnetometry, we show magnetic sensitivity approaching the Johnson-Nyquist noise limit of the system. This readout technique is viable for the many paramagnetic spin systems that exhibit resonances in the microwave domain. Our results pave a clear path to achieve unity readout fidelity of solid-state spin sensors through increased ensemble size, reduced spin-resonance linewidth, or improved cavity quality factor.

Dispersive readout of room-temperature ensemble spin sensors

“…This work has been supported by BMBF (Quant-ERA project MICROSENS), FWF (Quant-ERA SUMO), the European Union (Horizon 2020 research and innovation programme, grant agreement No 820394 (ASTER-IQS)), as well as by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under the German Excellence Strategy -EXC-2111 -390814868 and Emmy Noether grant RE3606/1-1. During compilation of the manuscript, we became aware of related work [30].…”