Traveling Wave Parametric Amplifier based on a chain of Coupled Asymmetric SQUIDs

TL;DR

This paper proposes a tunable traveling wave parametric amplifier using a chain of coupled asymmetric SQUIDs, enabling adjustable nonlinearity and phase matching for high-gain, broadband quantum and astronomical signal readout.

Contribution

It introduces a novel TWPA design with tunable nonlinearity via external magnetic flux, allowing phase matching and high performance in a compact form.

Findings

Achieves exponential gain with length tuning

Realizes >20 dB signal gain

Provides >5.4 GHz bandwidth and high saturation power

Abstract

A traveling wave parametric amplifier (TWPA) composed of a transmission line made up of a chain of coupled asymmetric superconducting quantum interference devices (SQUIDs) is proposed. The unique nature of this transmission line is that its nonlinearity can be tuned with an external magnetic flux and can even change sign. This feature of the transmission line can be used to perform phase matching in a degenerate four-wave mixing process which can be utilized for parametric amplification of a weak signal in the presence of a strong pump. Numerical simulations of the TWPA design have shown that with tuning, phase matching can be achieved and an exponential gain as a function of the transmission line length can be realized. The flexibility of the proposed design can realize: compact TWPAs with less than 211 unit cells, signal gains greater than 20 dB, 3 dB bandwidth greater than 5.4 GHz, and saturation powers up to -98 dBm. This amplifier design is well suited for multiplexed readout of quantum circuits or astronomical detectors in a compact configuration which can foster on-chip implementations.