144th RQC Seminar

• 講演者

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

• 日程

  2024年8月19日（月） 16:00-17:00 （4:00-5:00 p.m.）

• 開催場所

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

• 講演タイトル

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

• お問合せ

  rqc_info[at]ml.riken.jp

講演概要
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.