Perfect particle transmission through duality defects

Journal article

The theory of generalized symmetries has recently clarified how twisted sectors resolve the Callan–Rubakov paradox, where scattering of a charged particle by a magnetic monopole appeared to violate conservation laws. Here we study a more general setting of wavepackets that propagate across topological interfaces in quantum spin systems exhibiting non-invertible symmetries and across duality defects coupling dual theories. In these scenarios, we find that the transmission is always perfect and a particle traversing the interface is converted into a non-local string-like excitation. We give a systematic way of constructing such a defect by identifying its Hilbert space with the virtual bond dimension of the matrix product operator representing defect lines. Our work provides a precise characterization of topological interfaces in perfect transmission phenomena and yields a lattice analogue of the solution to the monopole paradox in quantum field theory.

Authors: Ueda, A; Vander Linden, V; De Vos, B; Lootens, L; Haegeman, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Physics
• Pages: 1-7
• Publication date: 2026-08-07
• DOI: 10.1038/s41567-026-03390-5
• EISSN: 1745-2481
• ISSN: 1745-2473
• Language: English
• Keywords: Operator (biology); Topological defect; Magnetic monopole; Duality (order theory); Quantum; Topology (electrical circuits); Homogeneous space; Lattice (music); Hilbert space