Characterizing cryogenic amplifiers with a matched temperature-variable noise source

Slawomir Simbierowicz (Corresponding Author), Visa Vesterinen, Joshua Milem, Aleksi Lintunen, Mika Oksanen, Leif Roschier, Leif Grönberg, Juha Hassel, David Gunnarsson, Russell E. Lake

Research output: Contribution to journalArticleScientificpeer-review

17 Citations (Scopus)


We present a cryogenic microwave noise source with a characteristic impedance of 50 ω, which can be installed in a coaxial line of a cryostat. The bath temperature of the noise source is continuously variable between 0.1 K and 5 K without causing significant back-action heating on the sample space. As a proof-of-concept experiment, we perform Y-factor measurements of an amplifier cascade that includes a traveling wave parametric amplifier and a commercial high electron mobility transistor amplifier. We observe system noise temperatures as low as 680-200+20 mK at 5.7 GHz corresponding to 1.5-0.7+0.1 excess photons. The system we present has immediate applications in the validation of solid-state qubit readout lines.
Original languageEnglish
Article number034708
Number of pages11
JournalReview of Scientific Instruments
Issue number3
Publication statusPublished - 11 Mar 2021
MoE publication typeA1 Journal article-refereed


V.V., L.G., and J.H. acknowledge financial support from the Academy of Finland through its Centers of Excellence Program (Project Nos. 312059 and 312294) and Grant No. 321700 and from the EU Flagship on Quantum Technology Grant No. H2020-FETFLAG-2018-03 Project No. 820363 OpenSuperQ.


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