(Quantum sensing with superconducting qubits for fundamental physics)


Recent progresses in the ability to measure and manipulate individual quanta such as microwave-photons, phonons and magnons are opening new directions in the detection of Dark Matter and of Fifth Forces, in tests of Quantum Gravity and of Quantum Mechanics of macroscopic objects. Superconducting qubits constitute a fundamental building block of this progress. In the last 15 years quantum sensing with superconducting qubits has moved from proof of principle to application to fundamental physics experiments, showing an unprecedent improvement in sensitivity. This was made possible by the ability to engineer and fabricate quantum devices and to manipulate the qubit state with classical fields. Quantum superposition and entanglement have been used to achieve Quantum Non Demolition detection of single photons and detection of itinerant photons, respectively, two fundamental features required by a microwave-photon detector in Axion dark-matter experiments.

The Qub-IT project aims to develop quantum sensing with superconducting qubits for present and future INFN fundamental-physics experiments. The main objective of the project is the realization of an itinerant single-photon counter that surpasses present devices in terms of efficiency and low dark-count rates by exploiting repeated QND measurements of a single photon and entanglement in multiple qubits. This device will find immediate application in light dark-matter searches.