- Accepted Paper
Strong-to-weak spontaneous symmetry breaking of higher-form noninvertible symmetries in Kitaev’s quantum double model
APS Open Sci. - Accepted 14 October, 2026
DOI: https://doi.org/10.1103/19sk-51np
APS Open Sci. - Accepted 14 October, 2026
DOI: https://doi.org/10.1103/19sk-51np
Topological orders can be understood as spontaneous symmetry breaking of higher-form symmetries. In the non-Abelian case, the broken higher-form symmetries are notably non-invertible. In this work, we extend this framework to mixed states, where symmetries can be either strong or weak. In particular, we investigate the strong-to-weak spontaneous symmetry breaking (SWSSB) of non-invertible higher-form symmetries in non-Abelian Kitaev’s quantum double models under decoherence. We further show that the resulting decohered quantum double mixed states form a locally indistinguishable set, which also constitutes an information convex set. Importantly, we emphasize that the dimension of this convex set equals the ground-state degeneracy of the corresponding pure state, highlighting that the quantum information encoded in the ground-state subspace is degraded into classical information captured by the convex set of decohered density matrices.
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