Superconducting Metamaterials

TL;DR

This paper demonstrates a new superconducting metamaterial design using Niobium that significantly reduces losses, enabling clearer observation of negative permittivity, permeability, and negative index passbands across a broad frequency range.

Contribution

It introduces a superconducting metamaterial approach with Niobium to lower losses and observe negative index phenomena more effectively than prior designs.

Findings

Negative effective permittivity and permeability observed in superconducting state

Evidence of a negative index passband between 50 MHz and 18 GHz

Dielectric loss of 3 x 10^{-3} at 10.75 GHz in superconducting wire array

Abstract

Evanescent wave amplification has been predicted under the ideal condition n = -1 + i 0 precisely, in the absence of retardation effects, but is difficult to observe in practice because current metamaterial designs suffer from high losses. We present results on a new metamaterial design that employs superconducting Niobium metals and low-loss dielectric materials to reduce the losses. We present transmission data on a wire medium, a split-ring resonator medium, and a combination of the two at temperatures between 4.2 K and room temperature. Evidence of negative effective permittivity, permeability, and a negative effective index passband are seen in the superconducting state between 50 MHz and 18 GHz. We find a dielectric loss of \epsilon_{eff,2} = 3 x 10^{-3} in a superconducting wire array at 10.75 GHz.