Josephson Metamaterial with a widely tunable positive/negative Kerr constant

TL;DR

This paper introduces a Josephson metamaterial with a chain of SQUIDs exhibiting a widely tunable Kerr nonlinearity, enabling efficient parametric amplification in microwave applications.

Contribution

It presents a novel Josephson metamaterial with a tunable Kerr constant, advancing the control of nonlinear effects for quantum microwave devices.

Findings

Kerr constant tunable from positive to negative

Good agreement between experiment and nonlinear Josephson chain theory

Potential for use in Josephson traveling-wave parametric amplifiers

Abstract

We report on the microwave characterization of a novel one-dimensional Josephson metamaterial composed of a chain of asymmetric superconducting quantum interference devices (SQUIDs) with nearest-neighbor coupling through common Josephson junctions. This metamaterial demonstrates a strong Kerr nonlinearity, with a Kerr constant tunable over a wide range, from positive to negative values, by a magnetic flux threading the SQUIDs. The experimental results are in good agreement with the theory of nonlinear effects in Josephson chains. The metamaterial is very promising as an active medium for Josephson traveling-wave parametric amplifiers; its use facilitates phase matching in a four-wave mixing process for efficient parametric gain.