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Quantum dot attached to superconducting leads: Relation between symmetric and asymmetric coupling

Result description

We study the Anderson single-level quantum dot attached to two BCS superconducting leads with the same gap size. We reveal that a system with asymmetric tunnel coupling to the leads (Gamma(L) not equal Gamma(R)) can be related to the symmetric system with the same net coupling strength Gamma=Gamma(L) + Gamma(R). Surprisingly, it is the symmetric case which is the most general, meaning that all physical quantities in the case of asymmetric coupling are fully determined by the symmetric ones. We give ready-to-use conversion formulas for the 0-pi phase transition boundary, on-dot quantities, and the Josephson current and illustrate them on the NRG results of Oguri, Tanaka and Bauer [Phys. Rev. B 87, 075432 (2013)] for the three-terminal setup. We apply our theory to the recent 0-p transition measurement of Delagrange et al. [Phys. Rev. B 93, 195437 (2016)] and determine the asymmetry of the experimental setup from the measured transition width. Finally, we establish that the widely assumed Kondo "universality" of physical quantities depending only on the ratio of the Kondo temperature and the superconducting gap T-K/Delta cannot hold for asymmetric junctions.

Keywords

devicesjunctionstransitiontransistorsimpuritysupercurrentjosephsoncarbon nanotubes

The result's identifiers

Alternative languages

  • Result language

    angličtina

  • Original language name

    Quantum dot attached to superconducting leads: Relation between symmetric and asymmetric coupling

  • Original language description

    We study the Anderson single-level quantum dot attached to two BCS superconducting leads with the same gap size. We reveal that a system with asymmetric tunnel coupling to the leads (Gamma(L) not equal Gamma(R)) can be related to the symmetric system with the same net coupling strength Gamma=Gamma(L) + Gamma(R). Surprisingly, it is the symmetric case which is the most general, meaning that all physical quantities in the case of asymmetric coupling are fully determined by the symmetric ones. We give ready-to-use conversion formulas for the 0-pi phase transition boundary, on-dot quantities, and the Josephson current and illustrate them on the NRG results of Oguri, Tanaka and Bauer [Phys. Rev. B 87, 075432 (2013)] for the three-terminal setup. We apply our theory to the recent 0-p transition measurement of Delagrange et al. [Phys. Rev. B 93, 195437 (2016)] and determine the asymmetry of the experimental setup from the measured transition width. Finally, we establish that the widely assumed Kondo "universality" of physical quantities depending only on the ratio of the Kondo temperature and the superconducting gap T-K/Delta cannot hold for asymmetric junctions.

  • Czech name

  • Czech description

Classification

  • Type

    Jimp - Article in a specialist periodical, which is included in the Web of Science database

  • CEP classification

  • OECD FORD branch

    10302 - Condensed matter physics (including formerly solid state physics, supercond.)

Result continuities

Others

  • Publication year

    2017

  • Confidentiality

    S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Data specific for result type

  • Name of the periodical

    Physical Review B

  • ISSN

    2469-9950

  • e-ISSN

  • Volume of the periodical

    95

  • Issue of the periodical within the volume

    19

  • Country of publishing house

    US - UNITED STATES

  • Number of pages

    9

  • Pages from-to

  • UT code for WoS article

    000401229000005

  • EID of the result in the Scopus database

    2-s2.0-85023627284

Result type

Jimp - Article in a specialist periodical, which is included in the Web of Science database

Jimp

OECD FORD

Condensed matter physics (including formerly solid state physics, supercond.)

Year of implementation

2017