MICROSENS

Detection and spectroscopy of weak microwave (>GHz) signals is of pivotal importance for key areas of modern technology, including wireless communication, radar, navigation and medical imaging. Solid state spins could be attractive sensors for both tasks since they have transition frequencies that can be tuned across the 1-100 GHz range. However high-frequency sensing by solid state spins has remained underexplored so far, and most demonstrations of spin sensing have focused on low-frequency (<10MHz) signals. The main reason is that well-established quantum sensing protocols suffer from a low efficiency in the high frequency domain. Furthermore, implementation of spin quantum sensors is not as mature compared to highly developed integrated microwave electronics. The purpose of the MICROSENS proposal is to use the well-known Nitrogen-Vacancy (NV) diamond color center as a tool to address these issues. We will build two different prototypes of microwave sensors based on the NV spin properties. The first one will be a single microwave photon detector and the second will be a wideband quantum spectrum analyser. Theoretical aspects will also be jointly addressed by the MICROSENS proposal since understanding the ultimate limits of noise for high-frequency spin sensing will be one of the main objectives of the MICROSENS proposal. Led by an industrial partner, MICROSENS federates leading European groups of experimental materials science, solid-state spin sensing and cavity QED. MICROSENS thereby brings together all the necessary blocks to achieve the ambitious target of produce MW detectors with outstanding performances occurring from the quantum properties of the probe. Research Targeted in the Call: MICROSENS will invent spin quantum sensors for detection and spectroscopy of weak microwave signals, bridging the research fields of spin sensors and microwave cavity-QED. Compared to conventional electronics, the resulting devices could be disruptive both in terms of sensitivity (down to single microwave photons) and simplicity (integration into IC-scale devices has been pioneered by the coordinator). We expect them to generate significant impact in several areas: Quantum-communication: where efficient detectors could pave the way to cryptography using microwave photons, potentially reaching across longer scales than conventional optics. Quantum computing: by studying transfer of short-lived fast processing qubits (microwave photons) to a long-lived memory (single spin). Quantum information sciences: by studying and applying a problem of nonequilibrium quantum thermodynamics, the interaction of an ultracold (mK) spin with a cold (K) photonic bath, mediated by a high-temperature (100K) cavity. Quantum metrology and sensing: by investigating protocols to suppress decoherence and sensitize spin sensors to microwave signals; by assessing their performance in real-world devices and their potential impact in radar, communication, navigation and medical imaging.