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IEEE International Conference on Microwaves, Communications, Antennas and Electronic Systems (COMCAS)

A Quantum Model for the Added Noise in SNAIL Traveling-Wave Parametric Amplifiers

Michael Haider, Yongjie Yuan, Christian Jirauschek

Published Jul 9, 2024• 0 citations
Publisher

Abstract

Broadband cryogenic traveling-wave parametric amplifiers are vital components for the readout of superconducting qubits. This is due to their large gain and quantum-limited noise performance. In this paper, we present analytic solutions for the equivalent added input fluctuations of state-of-the-art traveling-wave parametric amplifiers based on superconducting nonlinear asymmetric elements derived from a quantum mechanical model, including losses and dispersion.

DOI
10.1109/comcas58210.2024.10666167

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Substrate losses affect the performance of dispersive readout of superconducting qubits. We present a quantum mechanical model of a Josephson traveling-wave parametric amplifier, including substrate losses and the associated noise contributions. Losses and noise are introduced by coupling the system Hamiltonian to a bosonic bath, where the coupling constants can be related to the loss tangent of the transmission line substrate. Closed-form solutions for the temporal evolution of discrete mode operators in the presence of losses and noise are derived, under the assumption of a strong classical pump mode. A careful analysis of the loss-induced noise contributions can lead to the formulation of limits for the scaling of ultra-low noise qubit readout.