Quantum metric and effective mass of a two-body bound state in a flat band

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We consider two-body bound states in a flat band of a multiband system. The existence of pair dispersion predicts the possibility of breaking the degeneracy of the band and creating order, such as superconductivity. Within a separable interaction potential approximation, we find that the finiteness of the effective mass of a bound pair is determined by a band-structure invariant, which in the uniform case becomes the quantum metric. The results offer a simple foundation to understand and predict flat-band superconductivity. We propose an experiment to test the interaction-induced pair motion.
Original languageEnglish
Article number220511
Pages (from-to)1-5
JournalPhysical Review B
Issue number22
Publication statusPublished - 26 Dec 2018
MoE publication typeA1 Journal article-refereed


  • Condensed Matter - Superconductivity
  • Condensed Matter - Quantum Gases


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