Design and Measurement of a Josephson Traveling Wave Parametric Amplifier Fabricated in a Superconducting Qubit Process

Josephson junction based parametric amplifiers are used to read out the state of superconducting qubits with high fidelity. These amplifiers are themselves superconducting circuits operating at temperatures of tens of millikelvin. A version of this type of amplifier which has exhibited large bandwidth and saturation power is the Josephson traveling wave parametric amplifier (JTWPA). One particular JTWPA topology consists of hundreds to thousands of Josephson junctions in a transmission line configuration along with periodic phase matching resonators to increase gain. Here, we look at using a superconducting qubit fabrication process to realize this circuit.
To analyze the sensitivity of the JTWPA to fabrication process variation, we discuss a linear model for the circuit which takes into account unit cell to unit cell variation. To extract the measured circuit values, we use in-situ measurements of a JTWPA to compare the designed values to the realized values. Finally we discuss preliminary results realizing an example JTWPA design using a fabrication process designed for superconducting qubits.