2021/12/27 by Junhyun Lee, Lee, Junhyun, J. H. Pixley +1 · 2 citations
Materials Science · Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Disordered Systems and Neural Networks (cond-mat.dis-nn) #FOS: Physical sciences #Graphene research and applications #Quantum Gases (cond-mat.quant-gas) #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.2112.13797
openalex publication_date 2021/12/27 · openalex created_date 2022/10/07 · openalex updated_date 2026/07/28
This work theoretically explores how to emulate twisted double bilayer graphene with ultracold atoms in multiorbital optical lattices. In particular, the quadratic band touching of Bernal stacked bilayer graphene is emulated using a square optical lattice with px, py, and dx2-y2 orbitals on each site, while the effects of a twist are captured through the application of an incommensurate potential. The quadratic band touching is stable until the system undergoes an Anderson like delocalization transition in momentum space, which occurs concomitantly with a strongly renormalized single particle spectrum inducing flat bands, which is a generalization of the magic-angle condition realized in Dirac semimetals. The band structure is described perturbatively in the quasiperiodic potential strength, which captures miniband formation and the existence of magic-angles that qualitatively agrees with the exact numerical results in the appropriate regime. We identify several magic-angle conditions that can either have part or all of the quadratic band touching point become flat. In each case, these are accompanied by a diverging density of states and the delocalization of plane wave eigenstates. It is discussed how these transitions and phases can be observed in ultracold atom experiments.