Our proposal consists in a quantum sensor based on a superconduc:ng resonator. The working principle is based on the exponential growth of the susceptibility in proximity of a critical phase transition, where the system quickly switches from the vacuum state to a strong emission of easily detectable microwave signals, in response to extremely weak electromagnetic signals. The sensor can detect microwave and radiowave signals, with single-photon resolu:on.
The device is operated under cryogenic refrigera:on, and it can find a variety of applications in the context of superconduc:ng quantum technologies. In particular, the proposed device allows to: 1) readout the state of a quantum bit (qubit) with high fidelity and reducing the classical-electronic overhead; 2) Detect low-energy photons, with direct applications in the field of quantum sensing, computation, communications, and cryptography, and with possible applications to quantum radars.
The proposed device is based on a new concept, recently introduced in the research field of quantum information. The working principle exploits quantum phase transitions that have been theoretically predicted and then experimentally observed in many-body atomic physics. The proponents of this device have transferred this concept to the technological framework of solid- state quantum circuits, where the theoretical idea can be put into practice using current technology.
The proposed device boasts two clear advantages: 1) Intrinsic resilience to external noise and thermal fluctuations, which represent the main limitation to the standard approach to quantum sensing; 2) a significant simplification of both the fabrication and the opera:on stages, as the sensor does not require the generation of complex quantum states and it minimizes the classical- electronics overhead.