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谱分支与异常超流在耗散拓扑绝缘体基约瑟夫森结中的研究

Spectral Bifurcation and Anomalous Supercurrent in Dissipative Topological Insulator-based Josephson Junctions

Indian Institute of Technology, Kanpur(坎普尔印度理工学院);Physical Research Laboratory(物理研究实验室)

Ardamon Sten, Paramita Dutta, Sudeep Kumar Ghosh

AI总结:

研究揭示了耗散对拓扑绝缘体基约瑟夫森结中超导传输的影响,发现异常超流和马约拉纳束缚态寿命变化。

摘要:

拓扑保护与耗散之间的相互作用是实现混合量子设备的关键前沿。本文研究了在耗散拓扑绝缘体基约瑟夫森结中的传输特征,该平台直接探测量子相干性与损耗之间的竞争。我们通过将一个“耗损”金属电极耦合到结中来建模耗散,这通过使用林布兰德形式主义导出的非厄密特哈密顿量来有效描述。我们发现该结表现出不对称的复安德里效应谱,其中虚部能量成分对准束缚态的寿命施加有限影响。此外,在特定相区间之外,谱的实部发生分支:一条分支与连续谱合并,而另一条则穿透在超导能隙之下。关键的是,特征零能交叉点从ϕ=π移开并获得非零虚部;因此,相关的马约拉纳束缚态获得有限寿命,表明对耗散的鲁棒性丧失。最后,这种谱不对称性驱动了异常超流,表现为零相位差下的非零电流。我们的结果揭示了耗散如何从根本上重塑拓扑结中的超导传输,为耗散工程化的量子设备开辟了新方向。

英文摘要:

The interplay between topological protection and dissipation constitutes a critical frontier in the realization of hybrid quantum devices. Here, we investigate the transport signatures in a dissipative topological insulator-based Josephson junction, a platform that directly probes the competition between quantum coherence and loss. We model dissipation by coupling a `lossy' metallic lead to the junction, described effectively by a non-Hermitian Hamiltonian derived using the Lindblad formalism. We observe that the junction exhibits an asymmetric complex Andreev spectrum, where the imaginary energy component imposes a finite lifetime on the quasi-bound states. Furthermore, beyond specific phase intervals, the real component of the spectrum bifurcates: one branch merges with the continuum, while the other penetrates just below the superconducting gap. Crucially, the characteristic zero-energy crossing shifts away from $ϕ=π$ and acquires a non-zero imaginary component; consequently, the associated Majorana bound states acquire a finite lifetime, signaling a loss of robustness against dissipation. Finally, this spectral asymmetry drives an anomalous supercurrent, manifested as a non-vanishing current at zero phase difference. Our results reveal how dissipation fundamentally reshapes superconducting transport in topological junctions, opening new directions for dissipation-engineered quantum devices.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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