  Josephson junctions form the essential non-linearity for almost all
superconducting qubits. The junction is formed when two superconducting
electrodes come within $\sim$1 nm of each other. Although the capacitance of
these electrodes is a small fraction of the total qubit capacitance, the nearby
electric fields are more concentrated in dielectric surfaces and can contribute
substantially to the total dissipation. We have developed a technique to
experimentally investigate the effect of these electrodes on the quality of
superconducting devices. We use $\lambda$/4 coplanar waveguide resonators to
emulate lumped qubit capacitors. We add a variable number of these electrodes
to the capacitive end of these resonators and measure how the additional loss
scales with number of electrodes. We then reduce this loss with fabrication
techniques that limit the amount of lossy dielectrics. We then apply these
techniques to the fabrication of Xmon qubits on a silicon substrate to improve
their energy relaxation times by a factor of 5.
