Single-junction quantum-circuit refrigerator

V. Vadimov (Corresponding Author), Alexandra Viitanen, T. Mörstedt, T. Ala-Nissila, Mikko Möttönen

Research output: Contribution to journalArticleScientificpeer-review

6 Citations (Scopus)


We propose a quantum-circuit refrigerator (QCR) based on photon-assisted quasiparticle tunneling through a single normal-metal-insulator-superconductor (NIS) junction. In contrast to previous studies with multiple junctions and an additional charge island for the QCR, we directly connect the NIS junction to an inductively shunted electrode of a superconducting microwave resonator making the device immune to low-frequency charge noise. At low characteristic impedance of the resonator and parameters relevant to a recent experiment, we observe that a semiclassical impedance model of the NIS junction reproduces the bias voltage dependence of the QCR-induced damping rate and frequency shift. For high characteristic impedances, we derive a Born-Markov master equation and use it to observe significant non-linearities in the QCR-induced dissipation and frequency shift. We further demonstrate that, in this regime, the QCR can be used to initialize the linear resonator into a non-thermal state even in the absence of any microwave drive.

Original languageEnglish
Article number075005
Number of pages7
JournalAIP Advances
Issue number7
Publication statusPublished - 1 Jul 2022
MoE publication typeA1 Journal article-refereed


We thank Alexander Mel’nikov, Sergei Sharov, Dmitry Golubev, Gianluigi Catelani, and Matti Silveri for useful discussions. This work was financially supported by the European Research Council under Grant Nos. 681311 (QUESS) and 957440 (SCAR), the Academy of Finland under Grant No. 318937 and under its Centres of Excellence Program (Project Nos. 312300 and 312298), and the Finnish Cultural Foundation. We acknowledge the computational resources provided by the Aalto Science-IT project.


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