Anomalous Mixed-State Floquet Topology in One-Dimensional Open Quantum Systems

Fuente: arXiv
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Main Authors: Dinc, Görkem D., Schnell, Alexander, Martin, Andy M.
Format: Preprint
Published: 2026
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author Dinc, Görkem D.
Schnell, Alexander
Martin, Andy M.
author_facet Dinc, Görkem D.
Schnell, Alexander
Martin, Andy M.
contents We investigate the non-equilibrium topology of a periodically driven, dissipative Su-Schrieffer-Heeger chain using the ensemble geometric phase (EGP) $ϕ_{\mathrm{EGP}}$-a generalisation of the Zak phase to open quantum systems. In contrast to earlier work, we use Floquet-Born-Markov theory to describe the coupling to thermal reservoirs microscopically. We show that the steady state can be characterised by a Hermitian purity spectrum, providing a direct analogue of band topology for mixed states. The periodic drive induces nontrivial winding and a quasienergy spectrum with distinct $0$ and $π$ band gaps, with protected edge modes in each gap. We identify a pair of topological invariants $(ϕ^{0}_{\mathrm{EGP}}, Δϕ^π_{\mathrm{EGP}})$, revealing a structure consistent with a $\mathbb{Z}\times\mathbb{Z}$ classification known from isolated Floquet SSH systems, and show how it extends to a dissipative, finite-temperature setting in regimes where the steady-state structure remains well defined. Our results demonstrate when and how known Floquet topology survives in a driven-dissipative Gaussian steady state and establish Floquet topology as a robust concept beyond isolated zero-temperature systems. The underlying formalism provides a general framework for quadratic fermionic systems with linear bath couplings.
format Preprint
id arxiv_https___arxiv_org_abs_2604_25248
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Anomalous Mixed-State Floquet Topology in One-Dimensional Open Quantum Systems
Dinc, Görkem D.
Schnell, Alexander
Martin, Andy M.
Mesoscale and Nanoscale Physics
Statistical Mechanics
Quantum Physics
We investigate the non-equilibrium topology of a periodically driven, dissipative Su-Schrieffer-Heeger chain using the ensemble geometric phase (EGP) $ϕ_{\mathrm{EGP}}$-a generalisation of the Zak phase to open quantum systems. In contrast to earlier work, we use Floquet-Born-Markov theory to describe the coupling to thermal reservoirs microscopically. We show that the steady state can be characterised by a Hermitian purity spectrum, providing a direct analogue of band topology for mixed states. The periodic drive induces nontrivial winding and a quasienergy spectrum with distinct $0$ and $π$ band gaps, with protected edge modes in each gap. We identify a pair of topological invariants $(ϕ^{0}_{\mathrm{EGP}}, Δϕ^π_{\mathrm{EGP}})$, revealing a structure consistent with a $\mathbb{Z}\times\mathbb{Z}$ classification known from isolated Floquet SSH systems, and show how it extends to a dissipative, finite-temperature setting in regimes where the steady-state structure remains well defined. Our results demonstrate when and how known Floquet topology survives in a driven-dissipative Gaussian steady state and establish Floquet topology as a robust concept beyond isolated zero-temperature systems. The underlying formalism provides a general framework for quadratic fermionic systems with linear bath couplings.
title Anomalous Mixed-State Floquet Topology in One-Dimensional Open Quantum Systems
topic Mesoscale and Nanoscale Physics
Statistical Mechanics
Quantum Physics
url https://arxiv.org/abs/2604.25248