Wideband Josephson Parametric Amplifier with Integrated Transmission Line Transformer

Abstract: We describe a wide-band Josephson Parametric Amplifier (JPA) that is impedance-matched using an integrated compact superconducting transmission line transformer. The impedance transformer consists of two broadside coupled transmission lines configured in a Ruthroff topology which enables a wide matching bandwidth from 2 to 18 GHz, reducing the input line impedance and the device resonance quality factor by a factor of 4. This enables gain flatness and flexibility in the choice of the amplifier's tuning range. The amplifier has up to 20dB gain, with less than 1 dB of ripple, 2-3 GHz gain-bandwidth product and -126 dBm input 1-dB compression point. Moreover, the device active area fits into a 1mm x 1mm space, thus easing integration into large quantum systems.