Minimal resonator loss for circuit quantum electrodynamics
R. Barends, N. Vercruyssen, Akira Endo, Pieter de Visser, Tim Zijlstra, T. M. Klapwijk, P. Diener, S. J. C. Yates, J. J. A. Baselmans · Applied Physics Letters · 2010
We report quality factors of up to 500×103 in superconducting resonators at the single photon levels needed for circuit quantum electrodynamics. This result is achieved by using NbTiN and removing the dielectric from regions with high electric fields. As demonstrated by a comparison with Ta, the crucial sources of intensity-dependent loss are dielectrics on the surface of the metal and substrate.