Optimizing the Inelastic Cooper-pair Tunnelling Amplifier

Josephson parametric amplifiers have facilitated high-fidelity single-shot measurements, observation of quantum jumps, feedback-based algorithms etc. But their optimal operation requires a strong microwave pump and extensive filtering to avoid detrimental effects of the pump tone on other parts of the measurement chain. This represents a challenge when scaling to larger systems, such as quantum processors. In this talk, we present a DC-powered quantum-limited microwave amplifier requiring significantly lower hardware resources both inside and outside of a dilution refrigerator. Our Inelastic Cooper-pair Tunnelling Amplifier (ICTA) is based on a voltage-biased Josephson junction embedded in linear circuit presenting a well-designed impedance to the junction. The amplification process is driven by inelastic tunneling of Cooper pairs through the junction. We have already demonstrated quantum-limited noise performance of these these devices. Here, we will present our latest experimental results on ICTAs, in particular bandwidth engineering.