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IEEE Conference on Electrical Performance of Electronic Packaging and Systems (EPEPS)

Modeling Multiplexed Qubit Readout with a Josephson Traveling-Wave Parametric Amplifier

Samuel T. Elkin, Michael Haider, Thomas E. Roth

Published Oct 6, 2024• 1 citation
Publisher

Abstract

To model multiplexed readout, a key ingredient for scaling quantum computers, we develop a numerical method for co-simulation of qubits and a Josephson traveling-wave parametric amplifier. The integrated characterization reveals behavior absent from independent analyses.
DOI
10.1109/epeps61853.2024.10754033

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The development of large-scale superconducting quantum computers critically depends on the accurate readout of qubit states. To enable this, cryogenic parametric amplifiers have been proposed and developed, and have since found widespread use in small-signal detection applications. Among various amplifier architectures, Josephson traveling-wave parametric amplifiers (JTWPAs) are widely adopted due to their broad bandwidth, high saturation power, and compatibility with superconducting qubits. In this work, we present a design workflow of JTWPAs based on a co-simulation approach combining electromagnetic (EM) and circuit-level simulation. We apply this method to a uniform JTWPA, comparing our simulation results with experimental data. To mitigate the challenge of constructing lumped element circuit models usually used in conventional simulation method, we directly perform full EM analysis of the device to accurately determine its linear response. The extracted S parameters are then fed into a nonlinear harmonic balance simulator with Josephson junctions modeled as circuit elements. By doing so, the linear and gain properties of the JTWPA are extracted. Different factors that impact device performance including gain compression, phase matching, and fabrication imperfections are further investigated and modeled. A good agreement between simulation and measurements is identified, establishing the effectiveness of our approach in designing quantum parametric amplifiers.