Improved Nb SIS devices for heterodyne mixers between 700?GHz and 1.3?THz with NbTiN transmission lines using a normal metal energy relaxation layer

In this paper, we demonstrate experimentally the implementation of a niobium-trilayer junction with an aluminum-oxide tunnel barrier, embedded in a high-gap superconducting niobium-titanium-nitride circuit. Previously reported heating by quasiparticle trapping is removed by inserting a normal metal layer of gold between the niobium junction and...