Experimental characterization of RF-SQUIDs based Josephson Traveling Wave Parametric Amplifier exploiting Resonant Phase Matching scheme

In this contribution, we will present recent advances on Josephson Traveling Wave Parametric Amplifiers (JTWPAs) developed and tested in INRiM within the DARTWARS (Detector Array Readout with Traveling Wave AmplifieRS) project. JTWPAs are engineered metamaterials composed of a repetition of several hundreds of Josephson junctions embedded in a superconducting coplanar waveguide. The Josephson junctions confer to the material a non-linear behavior and promote a medium-mediated energy exchange, known as parametric down-conversion, between a strong propagating microwave tone and a couple of energy-preserving weak tones, called respectively signal and idler. This working principle makes the JTWPAs both an important tool for the quantum-limited broadband microwave amplification and for the emission of non-classical microwave radiation, being the signal and idler tones composed by entangled photons, exploitable in a wide variety of quantum sensing techniques (i.e., quantum illumination, quantum key distribution, etc.). In particular, we will present the architecture of an Al/Al-Ox/Al rf-SQUID-based JTWPA equipped with a resonant phase matching scheme, designed using finite element electromagnetic simulations in order to mitigate some typical unwanted effects like energy dissipation in higher-harmonics, internal reflections due to impedance mismatch and generation of slot line modes. The performance of this device, measured in a dilution refrigerator, will be quantified in terms of gain, bandwidth, and saturation power, while the signature of the emission of non-classical radiation will be detected employing IQ voltage quadratures correlation measurements.