Superconducting 3D-cavity architecture for microwave single-photon detection

Microwave single-photon detectors (SPDs) are essential quantum devices required in a large variety of quantum communication and quantum computation protocols. First microwave SPDs have been realized on the basis of superconducting qubits and resonators. Here, we experimentally study an SPD design compatible with a superconducting 3D-cavity architecture. We exploit the multimode nature of horseshoe aluminum cavities in combination with transmon qubits to experimentally realize an efficient detection of single microwave photons. We analyze the performance of such devices and discuss their possible applications in quantum microwave communication and sensing protocols.