Recently, great progress has been made in the field of ultrasensitive microwave detectors, reaching even the threshold for utilization in circuit quantum electrodynamics. However, cryogenic sensors lack the compatibility with broad-band metrologically traceable power absorption measurements at ultralow powers, which restricts their range of applications. Here, we demonstrate such measurements using an ultralow-noise nanobolometer, which we extend by an additional direct-current (dc) heater input. The tracing of the absorbed power relies on comparing the response of the bolometer between radio frequency and dc-heating powers traced to the Josephson voltage and quantum Hall resistance. To illustrate this technique, we demonstrate two different methods of dc-substitution to calibrate the power that is delivered to the base temperature stage of a dilution refrigerator using our in situ power sensor. As an example, we demonstrate the ability to accurately measure the attenuation of a coaxial input line between the frequencies of 50 MHz and 7 GHz with an uncertainty down to 0.1 dB at a typical input power of −114 dBm.
SormenjälkiSukella tutkimusaiheisiin 'Cryogenic sensor enabling broad-band and traceable power measurements'. Ne muodostavat yhdessä ainutlaatuisen sormenjäljen.
01/03/2023 → 31/08/2026
Projekti: EU: Framework programmes funding
ERC ConceptQ: New superconducting quantum-electric device concept utilizing increased anharmonicity, simple structure, and insensitivity to charge and flux noise
28/10/2022 → 31/10/2027
Projekti: EU: ERC grants
01/09/2020 → 31/08/2022
Projekti: Academy of Finland: Other research funding