University of Oulu

Partanen, M., Goetz, J., Tan, K., Kohvakka, K., Sevriuk, V., Lake, R., Kokkoniemi, R., Ikonen, J., Hazra, D., Mäkinen, A., Hyyppä, E., Grönberg, L., Vesterinen, V., Silveri, M., Möttönen, M. (2019) Exceptional points in tunable superconducting resonators. Physical review B, 100 (13), 134505. doi:10.1103/PhysRevB.100.134505

Exceptional points in tunable superconducting resonators

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Author: Partanen, Matti1,2; Goetz, Jan1; Tan, Kuan Yen1;
Organizations: 1QCD Labs, QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 13500, FI-00076 Aalto, Finland
2Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, DE-85748 Garching, Germany
3National Institute of Standards and Technology, Boulder, Colorado 80305, USA
4VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, FI-02044 VTT, Finland
5Research Unit of Nano and Molecular Systems, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.5 MB)
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Language: English
Published: American Physical Society, 2019
Publish Date: 2019-10-22


Superconducting quantum circuits are potential candidates to realize a large-scale quantum computer. The envisioned large density of integrated components, however, requires a proper thermal management and control of dissipation. To this end, it is advantageous to utilize tunable dissipation channels and to exploit the optimized heat flow at exceptional points (EPs). Here, we experimentally realize an EP in a superconducting microwave circuit consisting of two resonators. The EP is a singularity point of the effective Hamiltonian, and corresponds to critical damping with the most efficient heat transfer between the resonators without back and forth oscillation of energy. We observe a crossover from underdamped to overdamped coupling across the EP by utilizing photon-assisted tunneling as an in situ tunable dissipative element in one of the resonators. These methods can be used to obtain fast dissipation, for example, for initializing qubits to their ground states. In addition, these results pave the way for thorough investigation of parity-time symmetry and the spontaneous symmetry breaking at the EP in superconducting quantum circuits operating at the level of single energy quanta.

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Series: Physical review. B
ISSN: 2469-9950
ISSN-E: 2469-9969
ISSN-L: 2469-9950
Volume: 100
Issue: 13
Article number: 134505
DOI: 10.1103/PhysRevB.100.134505
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
Funding: We acknowledge the funding from the European Research Council under Consolidator Grant No. 681311 (QUESS), and Marie Skłodowska-Curie Grant No. 795159, the Academy of Finland through its Centres of Excellence Program (Projects No. 312300 and No. 312059) and Grants No. 265675, No. 305237, No. 305306, No. 308161, No. 312300, No. 314302, and No. 316551), the European Union via the Quantum Flagship project QMiCS (Grant No. 820505), the Vilho, Yrjö and Kalle Väisälä Foundation, the Technology Industries of Finland Centennial Foundation, the Jane and Aatos Erkko Foundation, the Alfred Kordelin Foundation, and the Emil Aaltonen Foundation.
Copyright information: Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.