理论物理所

Talks

Location: Home>Activities>Talks

(Seminar) Sub-gap states and supercurrent in hybrid superconductor-nanowire based quantum dot systems

04/24 2019
  • Title (Seminar) Sub-gap states and supercurrent in hybrid superconductor-nanowire based quantum dot systems
  • Speaker
  • Date
  • Venue
    • Abstract

    CAS Key Laboratory of Theoretical Physics

    Institute of Theoretical Physics

    Chinese Academy of Sciences

    Seminar

    Title

    题目

    		 Sub-gap states and supercurrent in hybrid superconductor-nanowire based quantum dot systems

    Speaker

    报告人

    Kasper Grove-Rasmussen

    Affiliation

    所在单位
    Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen

    Date

    日期
    2019年4月24日（周三）上午10：30
     

    Venue

    地点

    Seminar Room 322 Old ITP Building

    Abstract

    摘要

    		 I will present some of our recent understanding on quantum states in hybrid superconductor (S)-InAs semiconductor nanowire devices. When coupling a superconductor to a quantum dot (QD) system, the electron spin may be screened by quasiparticles above the gap in the superconductor similarly to the Kondo effect. This screening results in so-called Yu-Shiba-Rusinov (YSR) sub-gap states, which we explore in bottom-gated hybrid superconductor-nanowire single and double dot devices. The YSR state can qualitatively be modelled by using a simple zero-band width approximation, which is compared to measurements in single [1] and double quantum dots [2] coupled to a single superconductor, i.e. the N-QD-S and N-double QD-S configurations, respectively, where N is a normal electrode. Interestingly, in the latter case, the characteristic double dot honeycomb stability diagram is shown to be qualitatively different in the superconducting state for some coupling regimes. Finally, I will present, how supercurrent through these double dot structures in the S-double QD-S geometry can be used to identify the YSR ground state via a 0 to p transition in the current phase relation [3,4]. [1] A. Jellinggaard et al., Phys. Rev. B 94, 064520 (2016). [2] K. Grove-Rasmussen et al., Nat. Comm. 9 : 2376 (2018). [3] J.C. Estrada Saldana et al., Phys. Rev. Lett. 121, 257701 (2018) [4] J.C. Estrada Saldana et al., arXiv:1812.09303.

    Contact Person

    所内联系人

    		 Panagiotis Kotetes