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Emulating twisted double bilayer graphene with a multiorbital optical lattice
by Junhyun Lee, J. H. Pixley
This Submission thread is now published as
Submission summary
| Authors (as registered SciPost users): | Junhyun Lee · Jedediah Pixley |
| Submission information | |
|---|---|
| Preprint Link: | scipost_202203_00010v2 (pdf) |
| Date accepted: | 2022-07-05 |
| Date submitted: | 2022-05-24 00:55 |
| Submitted by: | Lee, Junhyun |
| Submitted to: | SciPost Physics |
| Ontological classification | |
|---|---|
| Academic field: | Physics |
| Specialties: |
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| Approach: | Theoretical |
Abstract
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 $p_x$, $p_y$, and $d_{x^2−y^2}$ 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.
Author comments upon resubmission
List of changes
1. We added Appendix A: Experimental realization, which explains the experimental parameters for the optical lattice and pre-tight binding approximation band structures. We also added a sentence in Sec. II referring to this appendix.
2. In Sec. IV, we clarified that the transition at large $W$ is a moir\'e transition and how this is related to the magic-angle transitions.
3. In Sec. V, we emphasized that high chemical potential is needed for the experimental realization.
4. We specified that the interaction can be tuned via a Feshbach resonance in Sec. V and included the references.
All changes are colored in blue in the resubmitted manuscript.
Published as SciPost Phys. 13, 033 (2022)
Reports on this Submission
Report #2 by Anonymous (Referee 4) on 2022-6-9 (Invited Report)
- Cite as: Anonymous, Report on arXiv:scipost_202203_00010v2, delivered 2022-06-09, doi: 10.21468/SciPost.Report.5211
Report
The authors have satisfied my concerns and questions from the last round of review through their detailed response as well as clarifications in the manuscript. I would also like to clarify the confusion I left in the 4-th question of my previous review. There, I was intended to ask how the solid line in Fig.3 will move upon increasing the order of the perturbation, which is merely from the perspective of presentation of this result, and I encourage the authors to also include the higher-order result in Fig.3. Nevertheless, the point that the higher-order perturbation prediction will move towards the numerical result is clear. In this sense, I recommend the manuscript to be published.