Superconducting Microstrip Losses at Microwave and Submillimeter Wavelengths

Abstract

Dielectric losses in superconducting microstrips often limit the performance of superconducting integrated devices at microwave and submillimeter wavelengths. Our current understanding of these losses is limited, though, especially at submillimeter wavelengths, due to a lack of experimental data. This study presents a chip that enables accurate loss measurements in both wavelength ranges. Data for a (Nb,Ti)N/$a$-Si/(Nb,Ti)N microstrip reveal much higher loss at submillimeter than at microwave wavelengths frequencies, which cannot be explained by the standard two-level-system model. This system should be very useful in further exploring these losses, to yield improved devices.