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arXiv · 2009.03010

Characterizing cryogenic amplifiers with a matched temperature-variable noise source

Slawomir Simbierowicz·Visa Vesterinen·Joshua Milem·Aleksi Lintunen·Mika Oksanen·Leif Roschier·Leif Grönberg·Juha Hassel·David Gunnarsson·Russell E. Lake
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Abstract

We present a cryogenic microwave noise source with a characteristic impedance of 50 $\Omega$, 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 $680^{+20}_{-200}$ mK at 5.7 GHz corresponding to $1.5^{+0.1}_{-0.7}$ excess photons. The system we present has immediate applications in the validation of solid-state qubit readout lines.

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Slawomir Simbierowicz, Visa Vesterinen, Joshua Milem, Aleksi Lintunen, Mika Oksanen, Leif Roschier, Leif Grönberg, Juha Hassel, David Gunnarsson, Russell E. Lake. 2020-09-07. Characterizing cryogenic amplifiers with a matched temperature-variable noise source. https://doi.org/10.1063/5.0028951

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