RQC Seminar

144th RQC Seminar

• Speaker

  Prof. Ravindra Chhajlany
  ( Solid State Theory Division, Faculty of Physics, Adam Mickiewicz University, Poland )

• Date

  16:00-17:00 (4:00-5:00 p.m.), August 19, 2024 (Monday)

• Venue

  Hybrid(ZOOM・ Wako Main Research 3F 345-347 Seminar Room/ 研究本館3階 セミナー室(345-347) C01）

• Title

  Controlled artificial quantum matter of excitons and atoms: from extended Bose-Hubbard models to twistless twistronics

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
I will provide an overview of some of our recent results on non-standard Hubbard models that can be engineered in controlled many body solid state and cold atom systems. I will first focus on how a system of dipolar excitons confined in a two-dimensional semiconductor lattice provides a realization of a generalized multiband extended Bose-Hubbard model with long range interactions leading to the observation of insulating phases at unit and fractional lattice filling. This finding motivates the wider question of identifying effects stemming from two-band physics in the strongly interacting regime. We consider this in the context of a generalized one-dimensional bosonic two band Hubbard model with on-site and nearest-neighbor interactions. In particular, we focus on “proximity” effects due to the interplay of two bands and find that coupling a density wave state in one band to a superfluid state in the other can lead to lattice supersolids. Interestingly, our results point towards the possibility of stabilizing a supersolid phase by thermally exciting one of the two bands, which counterintuitively can give rise to a supersolid obtained by heating. In the final part of the talk, time permitting, I will consider the quantum simulation of twistronics with cold atoms utilizing so-called synthetic dimensions. In particular, I will discuss our proposal of simulating twistronics without inducing a physical misalingment between two layers of a synthetic bilayer system. Instead, two synthetic layers are produced exploiting coherently coupled internal atomic states, and a supercell structure is generated via a spatially dependent Raman coupling. To illustrate this concept, we focus on a synthetic square bilayer lattice and show that it leads to tunable quasi-flat bands and Dirac cone spectra under certain magic supercell periodicities. The appearance of these features are explained using a perturbative analysis. I will also describe some effects stemming from attractive on-site interactions in this system.