Harmonic balance simulation of the influence of component uniformity and reliability on the performance of a Josephson traveling wave parametric amplifier

Abstract

The Josephson Traveling Wave Parametric Amplifier (JTWPA), which is a quantum-limited amplifier with high gain and large bandwidth, is the core device of large-scale measurement and control systems for quantum computing. A typical JTWPA consists of thousands of Josephson junctions (JJs) connected in series to form a transmission line, and hundreds of shunt LC resonators periodically loaded along the line for phase matching. Because the variation of these capacitors and inductors can be detrimental to its high frequency characteristics, the fabrication of a JTWPA typically necessitates precise processing equipment. To guide the fabrication process and further improve the design for manufacturability, it is necessary to understand how each electronic component affects the amplifier. In this letter, by using the harmonic balance method, we conduct a comprehensive study on the impact of nonuniformity and fabrication yield of the electronic components on the performance of JTWPA. The results provide insightful and scientific guidance for device design and fabrication processes.

Modeling of Josephson Traveling Wave Parametric Amplifiers

“…The socalled "ripples" in the gain profile are clearly visible, see the inset. They are due to variable impedance along the transmission line that do not well matches the input and output impedances and generate interference between forward and backward propagating waves undergoing multiple reflections [41] [43]. These ripples have been described as Fabry-Pérotlike resonances [26] [44] with a bandwidth inversely proportional to the waveguide length.…”