Tunable microwave impedance matching to a high impedance source using a Josephson metamaterial

We report the efficient coupling of a $50\,Ω$ microwave circuit to a high impedance conductor. We use an impedance transformer consisting of a $λ/4$ co-planar resonator whose inner conductor contains an array of superconducting quantum interference devices (SQUIDs), providing the resonator with a large and tunable lineic inductance $\mathcal{L}\sim 80 μ_0$, resulting in a large characteristic impedance $Z_C\sim 1\,\mathrm{k}Ω$. The impedance matching efficiency is characterized by measuring the shot noise power emitted by a dc biased high resistance tunnel junction connected to the resonator. We demonstrate matching to impedances in the $15$ to $35\,\mathrm{k}Ω$ range with bandwidths above $100\,\mathrm{MHz}$ around a resonant frequency tunable in the $4$ to $6\,\mathrm{GHz}$ range.

No reviews yet.

No comments yet.