Reducing vortex losses in superconducting microwave resonators with   microsphere patterned antidot arrays
  We experimentally investigate the vortex induced energy losses in niobium coplanar waveguide resonators with and without quasihexagonal arrays of nanoholes (antidots), where large-area antidot patterns have been fabricated using self-assembling microsphere lithography. We perform transmission spectroscopy experiments around 6.25 and 12.5 GHz in magnetic field cooling and zero field cooling procedures with perpendicular magnetic fields up to B=27 mT at a temperature T=4.2 K. We find that the introduction of antidot arrays into resonators reduces vortex induced losses by more than one order of magnitude. 
D. Bothner, C. Clauss, E. Koroknay, M. Kemmler, T. Gaber, M. Jetter,   M. Scheffler, P. Michler, M. Dressel, D. Koelle, and ...
cond-mat.supr-con