When Is Kramers-Wannier Duality Invertible?

Akash Sinha; Pramod Padmanabhan; Vladimir Korepin

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arXiv · 2609.20090

When Is Kramers-Wannier Duality Invertible?

Akash Sinha·Pramod Padmanabhan·Vladimir Korepin

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Abstract

{\it Kramers-Wannier} duality of the quantum Ising chain is naturally realized as a noninvertible transformation on a finite periodic chain. Upon incorporating appropriate symmetry-twisted sectors, however, the duality can be promoted to an invertible unitary transformation. In this Letter, we classify when the Kramers-Wannier duality admits an invertible realization on a finite Hilbert space. We show that this is determined by the representation of the Ising bond algebra and establish a necessary and sufficient condition in terms of its two central elements. This representation-theoretic criterion unifies the conventional noninvertible realization with invertible constructions involving symmetry-twisted sectors and applies equally to other models with the same underlying bond algebra. As an explicit example, we find an order-disorder duality in a non-trivial realization of the Ising bond algebra that admits an invertible Kramers-Wannier duality.

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Akash Sinha, Pramod Padmanabhan, Vladimir Korepin. 2026-09-17. When Is Kramers-Wannier Duality Invertible?. https://arxiv.org/abs/2609.20090

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