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arXiv:2607.22296

Unconventional $\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2$ topological order in the kagome XY toric code

C. Kölbl, M. Vieweg, K. P. Schmidt

cond-mat.str-elquant-phSubmitted Jul 24, 2026• Announced Jul 27, 2026• 0 citations
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Abstract

We investigate the quantum phase diagram of the XY toric code (XYTC) on the kagome lattice consisting of $XY$ hexagonal and triangular plaquette operators and conserved star operators. We demonstrate analytically by exploiting an exact local $\mathbb{Z}_2$-symmetry on dodecagons that the kagome XYTC realizes a $\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2$ topologically ordered phase in the limit of large hexagonal \mbox{plaquette} operators. This unconventional topological phase involves 64 quasi-particles - Abelian anyons - with restricted mobility on three colored sublattices establishing a quantum dimension of eight. The large number of topological superselection sectors originates from six independent Wilson loop operators, acting as emergent one-form symmetries. The resulting anyon structure is richer than that of established topological codes like the toric and the color code. A corresponding CSS topological stabilizer code is formulated, opening novel possibilities for the encoding and manipulation of topological quantum information.

Comments
11 pages, 6 figures

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Unconventional Z2×Z2×Z2\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2Z2​×Z2​×Z2​ topological order in the kagome XY toric code
We investigate the quantum phase diagram of the XY toric code (XYTC) on the kagome lattice consisting of XYXYXY hexagonal and triangular plaquette operators and conserved star operators. We demonstrate analytically by exploiting an exact local Z2\mathbb{Z}_2Z2​-symmetry on dodecagons that the kagome XYTC realizes a Z2×Z2×Z2\mathbb{Z}_2\times\mathbb{Z}_2\times\mathbb{Z}_2Z2​×Z2​×Z2​ topologically ordered phase in the limit of large hexagonal \mbox{plaquette} operators. This unconventional topological phase involves 64 quasi-particles - Abelian anyons - with restricted mobility on three colored sublattices establishing a quantum dimension of eight. The large number of topological superselection sectors originates from six independent Wilson loop operators, acting as emergent one-form symmetries. The resulting anyon structure is richer than that of established topological codes like the toric and the color code. A corresponding CSS topological stabilizer code is formulated, opening novel possibilities for the encoding and manipulation of topological quantum information.
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Stabilizer codes provide exact lattice realizations of bosonic topological orders. In contrast, systematic stabilizer descriptions of intrinsically fermionic topological phases remain much less developed. In this work, we introduce Majorana-Pauli stabilizer codes, a class of exactly solvable fermionic lattice models whose stabilizers are built from both generalized Pauli operators and Majorana operators. As a main example, we construct an exactly solvable stabilizer realization of the fermionic toric code: an intrinsically fermionic Z2\mathbb Z_2Z2​ topological order in (2+1)(2{+}1)(2+1) dimensions, using Z8\mathbb Z_8Z8​ Pauli operators coupled to Majorana modes. Within this stabilizer framework, the anyons, string operators, fusion rules, and braiding statistics all follow naturally from the stabilizer algebra. More broadly, we show that the fermionic toric code belongs to a duality web generated by anyon condensation and by gauging or ungauging bosonic or fermionic symmetries. This web connects bosonic topological orders, symmetry-enriched topological (SET) phases, and both bosonic and fermionic symmetry-protected topological (SPT) phases, all within a common stabilizer description. We extend this construction to all Abelian fermionic topological orders with gapped boundaries and to fermionic SPT phases whose fully gauged theories are Abelian. Going beyond Majorana operators, we introduce fermionic versions of the clock and shift operators and use them to construct an exact bosonization map for ZDF\mathbb Z_D^FZDF​ symmetries for DDD even. Using this, we realize a stabilizer model for a nontrivial Z8F\mathbb Z_8^FZ8F​ fermionic SPT phase with no free-fermion analog. Altogether, these results extend the stabilizer-code paradigm to a broad class of intrinsically fermionic phases bridging fermionic quantum many-body physics to quantum error correction.
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