Topological two-body bands in a multiband Hubbard model

Abstract

In a multiband Hubbard model the self-consistency relations for the two-body bound-state bands are in the form of a nonlinear eigenvalue problem. Assuming that the resultant eigenvectors form an orthonormal set, e.g., in the strong-binding regime, here we reformulate their Berry curvatures and the associated Chern numbers. As an illustration we solve the two-body problem in a Haldane-Hubbard model with attractive onsite interactions, and analyze its topological phase diagrams from weak to strong couplings, i.e., by keeping track of the gap closings in between the low-lying two-body bands. The resultant Chern numbers are consistent with the lobe structure of the phase diagrams in the strong-coupling regime.

9 pages with 2 figures (after first round of revision)

References in corpus (6)

• Two-body physics in the Su-Schrieffer-Heeger model
• Time-Reversal-Invariant Hofstadter-Hubbard Model with Ultracold Fermions
• Interaction-induced topological bound states and Thouless pumping in a one-dimensional optical lattice
• Topological two-body bound states in the interacting Haldane model
• Interaction-induced topological properties of two bosons in flat-band systems
• Dimers, trimers, tetramers, and other multimers in a multiband Bose-Hubbard model