Recent Developments in Quantum-Circuit Refrigeration

Timm Fabian Mörstedt*, Arto Viitanen, Vasilii Vadimov, Vasilii Sevriuk, Matti Partanen, Eric Hyyppä, Gianluigi Catelani, Matti Silveri, Kuan Yen Tan, Mikko Möttönen

*Corresponding author for this work

Research output: Contribution to journalReview Articlepeer-review

7 Citations (Scopus)
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The recent progress in direct active cooling of the quantum-electric degrees of freedom in engineered circuits, or quantum-circuit refrigeration is reviewed. In 2017, the discovery of a quantum-circuit refrigerator (QCR) based on photon-assisted tunneling of quasiparticles through normal-metal–insulator–superconductor junctions inspired a series of experimental studies demonstrating the following main properties: i) the direct-current (dc) bias voltage of the junction can change the QCR-induced damping rate of a superconducting microwave resonator by orders of magnitude and give rise to nontrivial Lamb shifts, ii) the damping rate can be controlled in nanosecond time scales, and ii) the dc bias can be replaced by a microwave excitation, the amplitude of which controls the induced damping rate. Theoretically, it is predicted that state-of-the-art superconducting resonators and qubits can be reset with an infidelity lower than 10−4 in tens of nanoseconds using experimentally feasible parameters. A QCR-equipped resonator has also been demonstrated as an incoherent photon source with an output temperature above 1 K yet operating at millikelvin. This source has been used to calibrate cryogenic amplification chains. In the future, the QCR may be experimentally used to quickly reset superconducting qubits, and hence assist in the great challenge of building a practical quantum computer.

Original languageEnglish
Article number2100543
Pages (from-to)1-14
Number of pages14
JournalAnnalen der Physik
Issue number7
Publication statusPublished - Jul 2022
MoE publication typeA2 Review article, Literature review, Systematic review


  • circuit quantum electrodynamics
  • Lamb shift
  • quantum environment engineering
  • quantum-circuit refrigerators
  • superconducting circuits


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