Temperature Dependence of Signal Intermodulation in a YBCO Resonator
Research Advisor: Dr. Stephen Remillard
Temperature and magnetic field dependence of second and third order intermodulation distortion levels (IMD2 and IMD3 respectively) were investigated for a type II superconducting resonator circuit. The circuit was comprised of a thin film of YBCO deposited on a substrate of LaAlO2. A carrier wave at a frequency equal to the resonant frequency of the circuit was introduced into the circuit via an electric coupling element. Two probe signals were injected into the circuit via a separate magnetic coupling element. The combination of these three signals locally excites second and third order IMD. A static magnetic field on the order of 238 Gauss was temporarily applied perpendicularly to the sample. Upon removal of the static magnetic field, both IMD2 and IMD3 levels were found to exponentially decay with time over a temperature range below 87.5K. Above 87.5K, however, IMD2 continued to exhibit exponential decay while IMD3 exhibited bounded exponential growth. The mechanism that causes IMD3 to change its decay mode is unclear at this time.
Funding for this project was provided by Award number DMR-1206149 from the National Science Foundation.