Traveling-Wave Parametric Amplifier: Phase matching in a Josephson Metamaterial with a tunable Kerr constant

We report on microwave characterization of a traveling-wave parametric amplifier (TWPA) composed of a unique Josephson metamaterial with a tunable Kerr constant. The strong nonlinear response of this metamaterial, which is composed of a chain of coupled asymmetric superconducting quantum interference devices, can be tuned by an external magnetic flux; its Kerr constant can even change sign. This tunability facilitates phase matching in a degenerate four-wave mixing process for efficient parametric amplification, and eliminates the need for dispersion engineering. In this talk we will discuss the metamaterial characterization as well as the preliminary measurements of a prototype TWPA (gain > 20 dB over a bandwidth of 9 GHz in a TWPA which is less than 3 mm long).