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20232026
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cond-mat.str-el2025

Higher-Form Anomalies on Lattices

Yitao Feng, Ryohei Kobayashi, Yu-An Chen +1

Higher-form symmetry in a tensor product Hilbert space is always emergent: the symmetry generators become genuinely topological only when the Gauss law is energetically enforced at…

cond-mat.str-el2024

Entanglement entropy in lattice models with quantum metric

Alexander Kruchkov, Shinsei Ryu

We revisit the connection between entanglement entropy and quantum metric in topological lattice systems, and provide an elegant and concise proof of this connection. In gapped two…

cond-mat.str-el2024

Higher Hall conductivity from a single wave function: Obstructions to symmetry-preserving gapped edge of (2+1)D topological order

Ryohei Kobayashi, Taige Wang, Tomohiro Soejima +2

A (2+1)D topological ordered phase with U(1) symmetry may or may not have a symmetric gapped edge state, even if both thermal and electric Hall conductivity are vanishing. It is re…

cond-mat.str-el2024

Higher bracket structure of density operators in Weyl fermion systems and topological insulators

Edwin Langmann, Shinsei Ryu, Ken Shiozaki

We study the algebraic structure of electron density operators in gapless Weyl fermion systems in spatial dimensions and in topological insulators (without any pro…

cond-mat.str-el2023

Spectral sum rules reflect topological and quantum-geometric invariants

Alexander Kruchkov, Shinsei Ryu

Topological invariants are fundamental characteristics reflecting global properties of quantum systems, yet their exploration has predominantly been limited to the static (DC) tran…

cond-mat.str-el2023

Noise probing of topological band gaps in dispersionless quantum states

Alexander Kruchkov, Shinsei Ryu

We uncover a useful connection between the integrated current noise and the topological band gap in dispersionless quantum states, $\int d ω[ \mathcal S^{\text{flat}}_{xx} +…