Superconducting coplanar nanolines with 50 nm linewidth
Long superconducting coplanar waveguides (CPWs) out of niobium on silicon wafers have been prepared. Inner conductor width, thickness and length are about 50 nm, 250 nm and 3.2 mm, respectively. The transition from small to large cross sections for 50 ? coaxial stright medium adaptor connectors is made by CPW tapers. The microwave characteristics are measured at 4.2 K via ?/2-resonators, where the inner conductor width wi is about half the London penetration depth. Due to the dominating kinetic inductance, the measured quality factor is close to an evaluated minimum value of wi<50 nm. The quality factors of such nanolines measured with niobium are approximately 150 at 10 GHz, and therefore more than two orders of magnitude larger than those measured with aluminum at the same temperature.
superconductivity waveguide nanowire dry-etching e-beam lithography