Measure of an ultranarrow topological gap via quantum noise

Alexander Kruchkov, Shinsei Ryu

Research output: Contribution to journalArticlepeer-review

Abstract

Advent of new-generation materials, with flat topological bands and ultranarrow band gaps (in the order of 1 meV), poses challenges on their precise characterization. We uncover a useful connection between the integrated current noise S(ω) and the topological band gap in dispersionless quantum states, ∫dω[Sxxflat+Syyflat]=Ce2Δ2 (in units ℏ=1), where C is the Chern number, e is electric charge, and Δ is the topological band gap. This relationship may serve as a working principle for experimental probe of topological band gaps in flat band materials. Possible applications include moiré systems, such as twisted bilayer graphene and twisted transition metal dichalcogenides, where a band gap measurement in meV regime presents an experimental challenge.

Original languageEnglish (US)
Article numberL041118
JournalPhysical Review B
Volume110
Issue number4
DOIs
StatePublished - Jul 15 2024

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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