Symmetry-protected Topological Scar Subspaces Stabilized by Restricted Algebras Enable Quantum Many-Body System Analysis
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Symmetry-protected topological phases of matter represent a fascinating area of modern physics, and researchers now extend these concepts beyond the traditional focus on ground states. Chihiro Matsui from The University of Tokyo, Thomas Quella from The University of Melbourne, and Naoto Tsuji from The University of Tokyo, lead a team that investigates how these topological properties emerge in dynamically isolated subspaces within complex systems. They propose a framework for understanding ‘symmetry-protected topological scar subspaces’, which arise from exceptional states within non-integrable systems, and demonstrate that these subspaces retain symmetries even when individual states do not. This work reveals that scar subspaces can not only inherit the topological characteristics of a system’s ground state, but also systematically modify them, potentially offering a new and experimentally viable platform for exploring symmetry-protected topology beyond the limitations of ground-state investigations.
Disorder Prevents Thermalization in Quantum Systems This research investigates how disorder can prevent energy from spreading out in quantum systems, a phenomenon known as Many-Body Localization (MBL). Normally, energy distributes evenly over time, but MBL effectively freezes the system in its initial state. Scientists explored the emergence of special states called quantum scars within these disordered systems, and how these scars break the typical rules of MBL.
The team focused on systems that are periodically driven, and discovered that quantum scars can appear even when the system is strongly disordered. These scars are characterized by the presence of edge modes, special states localized at the boundaries of the system, which act as pathways for energy flow.
This research advances our understanding of non-thermalizing systems and has implications for fields like quantum information processing, where localized states could protect quantum information from errors. The findings reveal that the existence of scars is linked to the local conservation laws inherent in MBL systems, which constrain the system’s dynamics. The discovery of new types of quantum scars and their interplay with MBL could also lead to the discovery of entirely new phases of matter and open up possibilities for manipulating quantum systems through a technique called Floquet engineering. Symmetry-Protected Topology in Quantum Many-Body Scars Scientists have discovered a surprising connection between symmetry-protected topological properties, usually found in the ground state of a material, and dynamically isolated energy states known as quantum many-body scars.
This research extends the concept of symmetry protection beyond the static ground state, revealing that these protective symmetries can also exist within specific, isolated energy levels of a non-integrable system.
The team introduced the concept of a symmetry-protected topological (SPT) scar subspace, demonstrating that these subspaces, when stabilized by specific algebraic structures and protected by fundamental symmetries, consistently exhibit topological characteristics. Applying this framework to the spin-1 Affleck, Kennedy, Lieb, Tasaki (AKLT) model, scientists showed that the resulting bimagnon scar subspace reflects the topological properties of the SPT ground state. Numerical simulations confirmed the presence of long-range string order within the scar subspace, providing further evidence of inherited topological characteristics. This work establishes a new platform for probing symmetry-protected topology beyond the conventional ground-state regime, offering a new way to explore topological phenomena in dynamically isolated quantum systems.
Symmetry Protection Extends to Quantum Scar States Scientists have demonstrated a novel connection between symmetry-protected topological properties and dynamically isolated energy states known as quantum scars.
This research extends the concept of symmetry protection beyond the usual static ground state, revealing that these protective symmetries can also exist within specific, isolated energy levels of a non-integrable system.
The team introduced the concept of a symmetry-protected topological (SPT) scar subspace, demonstrating that these subspaces, when stabilized by specific algebraic structures and protected by symmetries including on-site, inversion, and time-reversal, consistently exhibit topological characteristics. Investigating the spin-Affleck-Kennedy-Lieb-Tasaki (AKLT) model, scientists showed that its bimagnon scar subspace mirrors the topological properties of the corresponding SPT ground state. Numerical analysis verified long-range string order, a hallmark of topological order, within the bimagnon excitations.
The team confirmed the persistence of nonlocal string order, distinguishing the topological structure shared by both the ground state and the scar subspace. This work establishes a new platform for probing symmetry-protected topology beyond the ground-state regime, offering potential for exploring topological phenomena in dynamically isolated quantum systems.
Topological Scars Mirror Ground State Properties This research demonstrates that symmetry-protected topological properties, typically associated with a system’s ground state, can also emerge within dynamically isolated subspaces formed by exceptional energy eigenstates known as quantum many-body scars.
The team introduced the concept of a symmetry-protected topological (SPT) scar subspace, establishing that these subspaces, when stabilized by specific algebraic structures and protected by fundamental symmetries, consistently exhibit topological characteristics. Applying this framework to the Affleck-Kennedy-Lieb-Tasaki (AKLT) model, scientists showed that the resulting bimagnon scar subspace mirrors the topological properties of the system’s ground state. This correspondence is evidenced by appropriate symmetry representations, a predictable topological response, and the presence of long-range string order, all verified through numerical simulations.
The team confirmed the robustness of these topological features under perturbations that preserve the underlying symmetries. This work establishes a new platform for probing symmetry-protected topology beyond the traditional ground-state regime, offering a new way to explore topological phenomena in dynamically isolated quantum systems. 👉 More information 🗞 Symmetry-protected topological scar subspaces 🧠 ArXiv: https://arxiv.org/abs/2512.11216 Tags: