Two-Port Cryogenic Calibration for Microwave Measurements

Accurate superconducting resonator measurements and materials loss characterization are vitally important for the improvement of single-qubit performance and the development of quantum processors for superconducting quantum computing. Obtaining an accurate calibration is a challenge that prevents accurate and repeatable characterization of these superconducting microwave devices at cryogenic temperatures. A multiline through-reflect-line (TRL) calibration implemented on a commercial Vector Network Analyzer (VNA) can provide a solution to this problem, and is an avenue for further improvements in cryogenic microwave measurements. By accounting for impedance mismatches along the measurement chain before the calibration plane, we can measure those of the various connections at the device level --- including at the sample box, SMA connectors, and wirebonds. Furthermore, achieving a reliable impedance-correction based calibration is an important first step to implementing a source power calibration, which will allow an accurate determination of the power delivered to the device itself.