Tera-Hertz study of normal and superconducting transmission lines

Abstract

Electrical pulses as short as 0.6 ps in duration have been generated and sampled on coplanar transmission lines made of normal metals and superconductors to study the dispersion and loss spectrum in the frequency range up to 1 THz. The superconducting lines are superior when the loss of their normal metal counterparts is dominated by the resistance. However, the strong dispersion induced by the superconducting gap limits their usefulness to below the gap frequency, which is about 0.7 THz for superconducting Nb, and maybe as high as 16 THz for high-Tc superconducting oxides.