A 1-bit superconductive phase shifter in coplanar waveguide at Ka-band.

G. Bordier, Davide Cammilleri, B. Bélier +6 more

Kim Ho Yeap

In terahertz radio astronomy, superconducting coplanar waveguide resonators have been commonly applied in Kinetic Inductance Detectors (KIDs) to measure the absorption of photon energy in the millimeter and submillimeter bands. Here, we present an analysis on the performance of superconducting niobium coplanar waveguides (CPWs). To compute the loss in a superconducting CPW, we have incorporated the complex conductivity developed by Matis and Bardeen based on the superconducting BCS theory, into the CPW loss equation. We have made a comparison between the loss in a CPW at room temperature with that below the critical temperature Tc of the superconductor. It can be observed that at frequencies below the gap frequency fg, the low in the superconducting CPW is significantly lower than that in a normal CPW. Above fg, however, the material loses its superconductivity and the loss in both temperatures becomes comparable. In our analysi, we have also shown that the loss decreases as the gap bewteen the strip and groundplane becomes wider. Hence, with careful design, the loss in a CPW can actually be minimized.

Akira Endo, S. J. C. Yates, Juan Bueno +6 more

We show the first experimental results which prove that superconducting NbTiN coplanar–waveguide resonators can achieve a loaded Q factor in excess of 800 in the 350 GHz band. These resonators can be used as narrow band pass filters for on-chip filter bank spectrometers for astronomy. Moreover, the low-loss coplanar waveguide technology provides an interesting alternative to microstrip lines for constructing large scale submillimeter wave electronics in general.

M. Roesch, S. Wünsch, A. Stassen +2 more

Daniel Rocha-Aguilera, Gabriela Méndez‐Jerónimo, Joel Molina Reyes

Mohammad Hossein Amini, Ayaz Ghorbani, Abdolali Abdipour

Several studies have been conducted on field solutions of superconducting planar transmission lines; however, no study has been performed on superconducting grounded coplanar waveguides (GCPWs) which is a promising element, from the viewpoint of immunity to electromagnetic interference, in superconducting circuits. The purpose of this article is to analyze the superconducting GCPW to achieve the electrical parameters of the transmission line. In this regard, first, the magnetic field within the superconducting film is described through a 2-D wave equation. By introducing the proper boundary conditions acquired through the field solution of the structure, the proposed wave equation is solved and the magnetic field is obtained. Accordingly, the current distribution and the inductance of the line are evaluated which are of interest in the superconducting community. Compared with conventional coplanar waveguide (CPW), the GCPW structure experiences less current density at the edges. Hence, it supports a much more sustainable current. Further, it is shown that the GCPW exhibits less kinetic inductance during data transmission.