Non-periodic Boundary Conditions for Euler Class and Dynamical Signatures of Obstruction

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Autori principali: Alsaiari, Osama A., Bouhon, Adrien, Slager, Robert-Jan, Ünal, F. Nur
Natura: Preprint
Pubblicazione: 2025
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author Alsaiari, Osama A.
Bouhon, Adrien
Slager, Robert-Jan
Ünal, F. Nur
author_facet Alsaiari, Osama A.
Bouhon, Adrien
Slager, Robert-Jan
Ünal, F. Nur
contents While the landscape of free-fermion phases has drastically been expanded in the last decades, recently novel multi-gap topological phases were proposed where groups of bands can acquire new invariants such as Euler class. As in conventional single-gap topologies, obstruction plays an inherent role that so far has only been incidentally addressed. We here systematically investigate the nuances of the relation between the non-Bravais lattice configurations and the Brillouin zone boundary conditions (BZBCs) for any number of dimensions. Clarifying the nomenclature, we provide a general periodictization recipe to obtain a gauge with an almost Brillouin-zone-periodic Bloch Hamiltonian both generally and upon imposing a reality condition on Hamiltonians for Euler class. Focusing on three-band $\mathcal{C}_2$ symmetric Euler systems in two dimensions as a guiding example, we present a procedure to enumerate the possible lattice configurations, and thus the unique BZBCs possibilities. We establish a comprehensive classification for the identified BZBC patterns according to the parity constraints they impose on the Euler invariant, highlighting how it extends to more bands and higher dimensions. Moreover, by building upon previous work utilizing Hopf maps, we illustrate physical consequences of non-trivial BZBCs in the quench dynamics of non-Bravais lattice Euler systems, reflecting the parity of the Euler invariant. We numerically confirm our results and corresponding observable signatures, and discuss possible experimental implementations. Our work presents a general framework to study the role of non-trivial boundary conditions and obstructions on multi-gap topology that can be employed for arbitrary number bands or in higher dimensions.
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id arxiv_https___arxiv_org_abs_2507_22874
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Non-periodic Boundary Conditions for Euler Class and Dynamical Signatures of Obstruction
Alsaiari, Osama A.
Bouhon, Adrien
Slager, Robert-Jan
Ünal, F. Nur
Quantum Gases
Mesoscale and Nanoscale Physics
Atomic Physics
Quantum Physics
While the landscape of free-fermion phases has drastically been expanded in the last decades, recently novel multi-gap topological phases were proposed where groups of bands can acquire new invariants such as Euler class. As in conventional single-gap topologies, obstruction plays an inherent role that so far has only been incidentally addressed. We here systematically investigate the nuances of the relation between the non-Bravais lattice configurations and the Brillouin zone boundary conditions (BZBCs) for any number of dimensions. Clarifying the nomenclature, we provide a general periodictization recipe to obtain a gauge with an almost Brillouin-zone-periodic Bloch Hamiltonian both generally and upon imposing a reality condition on Hamiltonians for Euler class. Focusing on three-band $\mathcal{C}_2$ symmetric Euler systems in two dimensions as a guiding example, we present a procedure to enumerate the possible lattice configurations, and thus the unique BZBCs possibilities. We establish a comprehensive classification for the identified BZBC patterns according to the parity constraints they impose on the Euler invariant, highlighting how it extends to more bands and higher dimensions. Moreover, by building upon previous work utilizing Hopf maps, we illustrate physical consequences of non-trivial BZBCs in the quench dynamics of non-Bravais lattice Euler systems, reflecting the parity of the Euler invariant. We numerically confirm our results and corresponding observable signatures, and discuss possible experimental implementations. Our work presents a general framework to study the role of non-trivial boundary conditions and obstructions on multi-gap topology that can be employed for arbitrary number bands or in higher dimensions.
title Non-periodic Boundary Conditions for Euler Class and Dynamical Signatures of Obstruction
topic Quantum Gases
Mesoscale and Nanoscale Physics
Atomic Physics
Quantum Physics
url https://arxiv.org/abs/2507.22874