Calibrated Two-Port Microwave Measurement up to 26.5 GHz for Wide Temperature Range From 4 to 300 K

To realize a quantum information processing system, it is necessary not only to increase the number of physical qubits but also to cooperatively operate a multitude of cryogenic microwave components, such as cables, circulators, and amplifiers for controlling or reading them. Therefore, it is essential to develop metrological methods to precisely evaluate the microwave scattering parameters of each component at low temperatures. Here, we report a calibrated microwave measurement method for a wide temperature range of 4–300 K. At each temperature, we performed a full two-port calibration, which enables us to precisely measure the scattering parameters of various cryogenic microwave components up to 26.5 GHz by using 3.5-mm connectors as the reference planes. We carefully verified the validity of the calibration impedance elements and demonstrated our method by evaluating the temperature-dependent characteristics of a coaxial cable and a circulator.