约瑟夫森干涉中奇偶时间对称性的场控破缺与恢复
Field-controlled breaking and restoration of parity-time symmetry in Josephson interference
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中文总结 AI 辅助
本研究通过控制横向NbTi/PtTe₂/NbTi结中电流与磁场的相对取向，构建了可重构约瑟夫森干涉仪，实现了奇偶时间对称性的场控破缺与恢复。
中文摘要 AI 辅助
对称性在决定量子物质的相和物理性质方面起着基础性作用。在介观超导器件中调控对称性为重构其相位相干输运提供了途径。本文中，我们通过控制电流与磁场的相对取向，在横向NbTi/PtTe₂/NbTi结中演示了对称性选择性约瑟夫森干涉测量。从超电流干涉图样出发，我们构建了场-电流对称性图，该图可识别出器件级奇偶性（\u2118）、时间反演（\u2118）及其组合对称性\u2118\u2118被满足或被破坏的构型。在无面内磁场时，该结呈现对称的夫琅禾费图样；平行于电流的面内磁场会产生显著的旁瓣不对称性，而同时反转电流和完整的磁场构型则可恢复广义时间反演关系；值得注意的是，将面内磁场取向为垂直于电流，即使在相当大的场强下也能恢复奇偶时间对称的夫琅禾费响应。微观模型将该行为归因于无序诱导的势变化与面内磁场在超导电极附近产生的通量偶极子之间的相互作用。我们的结果构建了一种可重构约瑟夫森干涉仪，其中场-电流几何结构选择了所探测的对称操作，并在对称性破缺与对称性恢复的干涉态之间切换器件。
英文摘要
Symmetry plays a fundamental role in determining the phases and physical properties of quantum matter. Controlling symmetry in mesoscopic superconducting devices provides a route to reconfigure their phase-coherent transport. Here we demonstrate symmetry-selective Josephson interferometry in lateral NbTi/PtTe2/NbTi junctions by controlling the relative orientations of the current and magnetic field. From the supercurrent interference patterns, we construct a field-current symmetry map that identifies configurations exhibiting or violating the device-level parity (\mathcal{P}), time-reversal (\mathcal{T}) and their combined \mathcal{P}\mathcal{T} symmetry. In the absence of an in-plane field, the junction exhibits a symmetric Fraunhofer pattern. An in-plane field parallel to the current produces a pronounced side-lobe asymmetry, whereas reversing both the current and the complete magnetic-field configuration restores a generalized \mathcal{T} relation. Remarkably, orienting the in-plane field perpendicular to the current restores the \mathcal{P}\mathcal{T}-symmetric Fraunhofer response even at substantial field strengths. A microscopic model attributes this behavior to the interplay between disorder-induced potential variations and flux dipoles generated by in-plane-field Meissner focusing near the superconducting electrodes. Our results establish a reconfigurable Josephson interferometer in which the field-current geometry selects the symmetry operation being probed and switches the device between symmetry-broken and symmetry-restored interference states.
