Doubled Shapiro Steps in a Topological Josephson Junction

ORAL

Abstract


We study the transport properties of a superconductor-quantum spin Hall insulator- superconductor (S-QSHI-S) hybrid system in the presence of a microwave radiation. Instead of adiabatic analysis or using the resistively shunted junction model, we start from the microscopic Hamiltonian and calculate the DC current directly with the help of the non-equilibrium Green’s Functions method. The numerical results show that (i) the I-V curves of background current due to multiple Andreev reflections (MAR) exhibit a different structure with that in the conventional junctions, (ii) all Shapiro steps are visible and appear one by one at high frequency, while at low fre- quency, the steps evolve exactly as the Bessel functions and the odd steps are completely suppressed, implying a fractional Josephson effect.

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This work is supported by NBRP of China (2015CB921102 and 2014CB920901), National Key R and D Program of China (2017YFA0303301), NSF- China under Grants Nos. 11574007, 11204065, 11374219, 11574245, and 11534001.

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Presenters

  • Yu-Hang Li

    • International Center for Quantum Materials, Peking University

Authors

  • Yu-Hang Li

    • International Center for Quantum Materials, Peking University

  • Juntao Song

    • Department of Physics and Hebei Advanced Thin Film Laboratory, Hebei Normal University

  • Jie Liu

    • Department of Physics, Xian Jiaotong University
    • Department of Applied Physics, School of Science, Xian Jiaotong University

  • Hua Jiang

    • College of Physics, Optoelectronics and Energy, Soochow University

  • Qing-Feng Sun

    • International Center for Quantum Materials, School of Physics, Peking University
    • International Center for Quantum Materials, Peking University

  • Xincheng Xie

    • International Center for Quantum Materials and School of Physics, Peking University
    • Peking University
    • International Center for Quantum Materials, Peking University
    • International Center for Quantum Materials, School of Physics, Peking University
    • Peking Univ