Sub-kelvin thermometer for on-chip measurements of microwave devices utilizing two-level systems in superconducting microresonators
J. Wheeler, M. R. Vissers, M. Malnou, J. Hubmayr, J. N. Ullom, J. Gao
Abstract
We present a superconducting microresonator thermometer based on two-level systems (TLSs), which is drop-in compatible with cryogenic microwave systems. The operational temperature range is 50–1000 mK (which may be extended to 5 mK), and the sensitivity (50–75 μK/Hz) is relatively uniform across this range. The miniature footprint that conveniently attaches to the feedline of a cryogenic microwave device facilitates the measurement of on-chip device temperature and requires no additional thermometry wiring or readout electronics. We demonstrate the practical use of these TLS thermometers to investigate static and transient chip heating in a kinetic inductance traveling-wave parametric amplifier operated with a strong pump tone. TLS thermometry may find broad application in cryogenic microwave devices such as superconducting qubits and detectors.