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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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