We report a technique for applying a dc voltage or current bias to the center conductor of a high-quality factor superconducting microwave cavity without significantly disturbing selected cavity modes. This is accomplished by incorporating dc bias lines into the cavity at specific locations. The measured S-matrix parameters of the system are in good agreement with theoretical predictions and simulations. We find that at 4 K the quality factor of the cavity degrades by less than 1% under the application of a dc bias.
@article{arxiv.1101.4218,
title = {Introduction of a DC Bias into a High-Q Superconducting Microwave Cavity},
author = {Fei Chen and A. J. Sirois and R. W. Simmonds and A. J. Rimberg},
journal= {arXiv preprint arXiv:1101.4218},
year = {2011}
}