University of Oulu

Masuda, S., Tan, K., Partanen, M., Lake, R., Govenius, J., Silveri, M., Grabert, H., Möttönen, M. (2018) Observation of microwave absorption and emission from incoherent electron tunneling through a normal-metal–insulator–superconductor junction. Scientific Reports, 8 (1), doi:10.1038/s41598-018-21772-5

Observation of microwave absorption and emission from incoherent electron tunneling through a normal-metal–insulator–superconductor junction

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Author: Masuda, Shumpei1; Tan, Kuan Y.1; Partanen, Matti1;
Organizations: 1QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, PO Box 13500, AALTO, FI-00076, Finland
2Research Unit of Theoretical Physics, University of Oulu, Oulu, FI-90014, Finland
3Department of Physics, University of Freiburg, Freiburg im Breisgau, Germany
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
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Language: English
Published: Springer Nature, 2018
Publish Date: 2018-03-14


We experimentally study nanoscale normal-metal–insulator–superconductor junctions coupled to a superconducting microwave resonator. We observe that bias-voltage-controllable single-electron tunneling through the junctions gives rise to a direct conversion between the electrostatic energy and that of microwave photons. The measured power spectral density of the microwave radiation emitted by the resonator exceeds at high bias voltages that of an equivalent single-mode radiation source at 2.5 K although the phonon and electron reservoirs are at subkelvin temperatures. Measurements of the generated power quantitatively agree with a theoretical model in a wide range of bias voltages. Thus, we have developed a microwave source which is compatible with low-temperature electronics and offers convenient in-situ electrical control of the incoherent photon emission rate with a predetermined frequency, without relying on intrinsic voltage fluctuations of heated normal-metal components or suffering from unwanted losses in room temperature cables. Importantly, our observation of negative generated power at relatively low bias voltages provides a novel type of verification of the working principles of the recently discovered quantum-circuit refrigerator.

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Series: Scientific reports
ISSN: 2045-2322
ISSN-E: 2045-2322
ISSN-L: 2045-2322
Volume: 8
Issue: 1
Article number: 3966
DOI: 10.1038/s41598-018-21772-5
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Funding: We have received funding from the European Research Council under Starting Independent Researcher Grant No. 278117 (SINGLEOUT) and under Consolidator Grant No. 681311 (QUESS), the Academy of Finland through its Centres of Excellence Program (project Nos. 312300, 251748 and 284621) and grants (Nos. 265675, 314449 286215, 308161, 314302, 305237, and 305306), the Emil Aaltonen Foundation, the Jenny and Antti Wihuri Foundation, the Alfred Kordelin Foundation, the Finnish Cultural Foundation, the Technology Industries of Finland Centennial Foundation, Jane and Aatos Erkkos Foundation, and the Vilho, Yrjö and Kalle Väisälä Foundation.
Academy of Finland Grant Number: 312300
Detailed Information: 312300 (Academy of Finland Funding decision)
251748 (Academy of Finland Funding decision)
284621 (Academy of Finland Funding decision)
265675 (Academy of Finland Funding decision)
314449 (Academy of Finland Funding decision)
286215 (Academy of Finland Funding decision)
308161 (Academy of Finland Funding decision)
314302 (Academy of Finland Funding decision)
305237 (Academy of Finland Funding decision)
305306 (Academy of Finland Funding decision)
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