We have developed a novel Josephson junction geometry with minimal volume of lossy isolation dielectric, being suitable for higher quality trilayer junctions implemented in qubits. The junctions are based on in-situ deposited trilayers with thermal tunnel oxide, have micron-sized areas and a low subgap current. In qubit spectroscopy only a few avoided level crossings are observed, and the measured relaxation time of T1≈400nsec is in good agreement with the usual phase qubit decay time, indicating low loss due to the additional isolation dielectric.
@article{arxiv.1101.0232,
title = {Phase qubits fabricated with trilayer junctions},
author = {M. Weides and R. C. Bialczak and M. Lenander and E. Lucero and Matteo Mariantoni and M. Neeley and A. D. O'Connell and D. Sank and H. Wang and J. Wenner and T. Yamamoto and Y. Yin and A. N. Cleland and J. Martinis},
journal= {arXiv preprint arXiv:1101.0232},
year = {2011}
}