NbN films with high kinetic inductance for high-quality compact superconducting resonators
Simone Frasca, Ivo Arabadzhiev, Sebastien Yves Bros de Puechredon, F. Oppliger, Vincent Jouanny, Roberto Musio, Marco Scigliuzzo, Fabrizio Minganti, Pasquale Scarlino, Edoardo Charbon
Abstract
Niobium nitride ($\mathrm{Nb}\mathrm{N}$) is a particularly promising material for quantum technology applications, as it shows the degree of reproducibility necessary for large-scale superconducting circuits. We demonstrate that resonators based on $\mathrm{Nb}\mathrm{N}$ thin films present a one-photon internal quality factor above ${10}^{5}$ maintaining a high impedance (larger than $2\mathrm{k}\mathrm{\ensuremath{\Omega}}$), with a footprint of approximately $50\ifmmode\times\else\texttimes\fi{}100\phantom{\rule{0.2em}{0ex}}\text{\ensuremath{\mu}}{\mathrm{m}}^{2}$ and a Kerr nonlinearity of few tenths of a hertz. These quality factors, mostly limited by losses induced by the coupling to two-level systems, have been maintained for kinetic inductances ranging from tenths to hundreds of picoHenry per square. We also demonstrate minimal variations in the performance of the resonators during multiple cooldowns over more than nine months. Our work proves the versatility of niobium nitride high-kinetic-inductance resonators, opening perspectives towards the fabrication of compact, high-impedance, and high-quality multimode circuits, with sizable interactions.