Perfect Particle Transmission through Duality Defects

TL;DR

This paper demonstrates that wavepackets can pass through topological interfaces and duality defects in quantum spin systems without loss, transforming into nonlocal excitations, and provides a systematic construction method for such defects.

Contribution

It introduces a systematic way to construct duality defects with perfect transmission, linking topological interfaces to matrix product operators in quantum spin systems.

Findings

Wavepackets transmit perfectly across topological interfaces.

Particles convert into nonlocal string-like excitations at defects.

Provides a lattice analogue of the monopole paradox solution.

Abstract

We study wavepackets that propagate across (a) topological interfaces in quantum spin systems exhibiting non-invertible symmetries and (b) duality defects coupling dual theories. We demonstrate that the transmission is always perfect, and that a particle traversing the interface is converted into a nonlocal 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 both gives an operational meaning to topological interfaces, and provides a lattice analogue of recent results solving the monopole paradox in quantum field theory.