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arXiv · 2603.22163

Dissipative free fermions in disguise

Kohei Fukai·Hironobu Yoshida·Hosho Katsura
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Abstract

Recently, a class of spin chains known as ``free fermions in disguise'' (FFD) has been discovered, which possess hidden free-fermion spectra even though they are not solvable via the standard Jordan-Wigner transformation. In this work, we extend this FFD framework to open quantum systems governed by the Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) equation. We establish a general class of exactly solvable open quantum systems within the FFD framework: if the Liouvillian frustration graph is claw-free and has a simplicial clique, the Liouvillian possesses a hidden free-fermion spectrum. In particular, the (even-hole, claw)-free condition automatically guarantees this, enabling exact computation of the Liouvillian gap and an infinite-temperature autocorrelation function. Our results provide the first realization of the FFD mechanism in open quantum systems.

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Kohei Fukai, Hironobu Yoshida, Hosho Katsura. 2026-03-23. Dissipative free fermions in disguise. https://arxiv.org/abs/2603.22163

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