Mixed-state phase structure of gauge-Higgs subsystem codes under logical-preserving decoherence

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Hauptverfasser: Kuno, Yoshihito, Ichinose, Ikuo
Format: Preprint
Veröffentlicht: 2025
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author Kuno, Yoshihito
Ichinose, Ikuo
author_facet Kuno, Yoshihito
Ichinose, Ikuo
contents Some of lattice-gauge-theory models, in particular gauge-Higgs model (GHM), can be regarded and work as a subsystem code. This work studies the effect of local-gauge-symmetric decoherence on the GHM from the perspective of the subsystem code. We clarify the global phase diagram of the subsystem code. In particular, the decoherence induces an unconventional critical mixed state, where the logical information is preserved but the rest of the system exhibits mixed state criticality. For a fixed point, the decohered subsystem code is understood by the ``gauging out" prescription. By mapping the GHM to the toric code subject to decoherence, we can understand the properties of the subsystem code. We further discuss and investigate the robustness of the logical space of the subsystem code. Although this kind of subsystem code can be produced by using any bulk mixed state in the GHM, its robustness is a subtle problem due to the mixed critical gauge qubits. We consider some specific unitary for examining the robustness of the stored quantum information. For dynamical unitary perturbations described by interactions between the logical qubit and gauge qubits, the deformation of the subsystem code drastically depends on the initial mixed state of the gauge qubits.
format Preprint
id arxiv_https___arxiv_org_abs_2511_08076
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Mixed-state phase structure of gauge-Higgs subsystem codes under logical-preserving decoherence
Kuno, Yoshihito
Ichinose, Ikuo
Quantum Physics
Statistical Mechanics
High Energy Physics - Lattice
Some of lattice-gauge-theory models, in particular gauge-Higgs model (GHM), can be regarded and work as a subsystem code. This work studies the effect of local-gauge-symmetric decoherence on the GHM from the perspective of the subsystem code. We clarify the global phase diagram of the subsystem code. In particular, the decoherence induces an unconventional critical mixed state, where the logical information is preserved but the rest of the system exhibits mixed state criticality. For a fixed point, the decohered subsystem code is understood by the ``gauging out" prescription. By mapping the GHM to the toric code subject to decoherence, we can understand the properties of the subsystem code. We further discuss and investigate the robustness of the logical space of the subsystem code. Although this kind of subsystem code can be produced by using any bulk mixed state in the GHM, its robustness is a subtle problem due to the mixed critical gauge qubits. We consider some specific unitary for examining the robustness of the stored quantum information. For dynamical unitary perturbations described by interactions between the logical qubit and gauge qubits, the deformation of the subsystem code drastically depends on the initial mixed state of the gauge qubits.
title Mixed-state phase structure of gauge-Higgs subsystem codes under logical-preserving decoherence
topic Quantum Physics
Statistical Mechanics
High Energy Physics - Lattice
url https://arxiv.org/abs/2511.08076