Impedance matched Josephson parametric amplifier with a multisection λ/4 transmission line transformer

We report the fabrication and characterization of an impedance matched Josephson parametric amplifier (IMPA). A multisection λ/4 transmission line transformer (TLT) is utilized, which can reduce the input impedance and provide a wide impedance matched bandwidth. In addition, the whole IMPA device is fabricated on a LaAlO3 substrate with a dielectric constant of 23.4, much larger compared to the commonly used intrinsic silicon substrate, to provide larger grounded capacitance, making the fabrication of the multisection λ/4 TLT more precise and reliable. The experimental results show that by adjusting the working point, the amplifier has a bandwidth of 580 MHz with a gain of more than 15 dB. The average input saturation power is about −115 dBm within the bandwidth. Additionally, its noise performance is close to the quantum-limited level.