Microwave Superconductivity

Stephen K. RemillardPhysics

remillard@hope.edu

616-395-7507

Education and experiencesPh.D. The College of William and Mary (1993)B.S., Calvin College (1988)Grand Valley State University, Visiting Asst. Prof (2005-7)Calvin College, Visiting Assistant Professor (2004-5)ISCO International, Director of Engineering (1994-2003)

Grants and awardsMicrowave & Materials Designs, Ltd. Pty., Corporate sponsorship, Microwave Device Science and Technology (2007-2008)

Key publicationsS.K. Remillard et al., A Review of HTS Thick Film Microwave Filter Technology, J. of Supercond., 19, no. 7-8, pp. 523-530 (2006).S. K. Remillard, et al. Three-Tone Intermodulation Distortion Generated by Superconducting Bandpass Filters, IEEE Trans. Appl. Superconductivity, 13, 3797 (2003).S.K. Remillard et al., Field Deployable Microwave Filters Made from YBa2Cu3O7-δ Thick Films, J. of Supercond., no. 14, p. 47 (2001).

Areas of expertise: Solid State Physics, Microwave Techniques in Measurement, Superconductivity

Acknowledgements: M&MD, Ltd. Pty. of Australia

Our work with high temperature superconductors can only be carried out at very low, or cryogenic, temperatures. So the platform for the experiment begins with a cryogenic refrigerator which cools the superconductors to about 50 degrees above absolute zero. We use a sapphire resonator, pictured above, to immerse the superconductors in a microwave field which offers us the rare opportunity to observe electrical resistance in the superconducting material. Using a mix of cryogenic and microwave techniques, we are studying the nature of this resistance. Of particular interest is the nonlinear surface resistance. Just as the ballast in a fluorescent light offers a resistance that changes with the current flowing through it, the superconductor’s surface resistance changes with current. This “nonlinearity” gives rise to distortion in signals passing through superconducting electronic devices. Our research seeks to understand the sources of this nonlinearity, and will hopefully have a direct impact on the future of cryogenic electronics.