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arXiv 2307.04789cond-mat.mes-hall
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非厄米约瑟夫森结中的反常安德列夫能谱与输运

Anomalous Andreev Spectrum and Transport in Non-Hermitian Josephson Junctions

Chang-An Li, Hai-Peng Sun, Björn Trauzettel

AI总结:

本研究提出相位偏置非厄米约瑟夫森结结构,推导其有效哈密顿量,发现复安德列夫能谱与约瑟夫森能隙等特殊特征,提出复超流表征反常输运,证实非厄米物理对约瑟夫森效应的强烈影响。

摘要:

我们提出一种由短程非厄米连接介导的两个超导体构成的相位偏置非厄米约瑟夫森结(NHJJ)。该NHJJ由弱耦合区基于林德布拉德形式体系推导的有效非厄米哈密顿量描述。通过求解Bogoliubov-de Gennes方程,我们发现其作为相位差函数的安德列夫能谱呈现约瑟夫森能隙,即不存在安德列夫(准)束缚态的有限相位窗口。复安德列夫能谱与约瑟夫森能隙的存在构成了NHJJ的特殊能谱特征。此外,我们提出由非弹性库珀对隧穿产生的复超流,以表征NHJJ中的反常输运。额外的数值模拟补充了我们的解析预测。我们证明约瑟夫森效应受非厄米物理的强烈影响。

英文摘要:

We propose a phase-biased non-Hermitian Josephson junction (NHJJ) composed of two superconductors mediated by a short non-Hermitian link. Such a NHJJ is described by an effective non-Hermitian Hamiltonian derived based on the Lindblad formalism in the weak coupling regime. By solving the Bogoliubov-de Gennes equation, we find that its Andreev spectrum as a function of phase difference exhibits Josephson gaps, i.e., finite phase windows with no Andreev (quasi)bound states. The complex Andreev spectrum and the presence of Josephson gaps constitute particular spectral features of the NHJJ. Moreover, we propose complex supercurrents arising from inelastic Cooper pair tunneling to characterize the anomalous transport in the NHJJ. Additional numerical simulations complement our analytical predictions. We demonstrate that the Josephson effect is strongly affected by non-Hermitian physics.

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