Characterizing S-Parameters of Microwave Coaxial Devices With up to Four Ports at Temperatures of 3 K and Above for Quantum Computing Applications

Multiport microwave devices operating at cryogenic temperatures are used in quantum computing to enable complex quantum operations. These components need to be precisely characterized at their operating temperature to ensure adequate overall system performance. In this work, an $S$ -parameter measurement system to characterize the performance of coaxial connectorized microwave devices having up to four ports at the temperatures of 3 K and above is presented. A four-port calibration setup is implemented at the 3 K temperature stage inside a dilution refrigerator. Measurement results for devices under test at 3 K are presented, and the performance of the measurement system is evaluated.