Field-controlled breaking and restoration of parity-time symmetry in Josephson interference
cond-mat.mes-hall, cond-mat.supr-con
Submitted: 2026-08-17
Updated: 2026-10-11
Comments: Main text: 12 pages, 4 figures. Supplementary Information: 24 pages, 18 figures
License: http://creativecommons.org/licenses/by/4.0/
The gist: Symmetry plays a fundamental role in determining the phases and physical properties of quantum matter.
Abstract
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/PtTe 2 /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 (P), time-reversal (T) and their combined PT 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 T relation. Remarkably, orienting the in-plane field perpendicular to the current restores the PT-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.
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