Flat Bands: Fundamentals and Applications

A special issue of Photonics (ISSN 2304-6732).

Deadline for manuscript submissions: closed (20 June 2023) | Viewed by 5123

Special Issue Editors

Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China
Interests: nonlinear optics; beam shaping and optical manipulation; photonic flat bands; photonic lattices; topological photonics

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Guest Editor
Engineering Laboratory for Optoelectronic Technology and Advanced Manufacturing, School of Physics, Henan Normal University, Xinxiang 453007, China
Interests: photonic lattices; non-Hermitian systems; flat-band localization; flat-band quantum effect

Special Issue Information

Dear Colleagues,

Flat-band systems, as represented by lattices hosting at least one completely dispersionless energy band, have attracted enormous interest in different branches of physics, ranging from condensed matter to exciton polaritons, and from ultracold atoms to photonics. As the kinetic energy is completely quenched, particle-enhanced interaction makes flat-band systems a perfect candidate for the investigation of complex many-body quantum states and strongly correlated many-body physics in the absence of a magnetic field. On the other hand, advances in fabrication techniques not only provide insights into fundamental concepts and phenomena and motivate the continued study of disordered, quantum, and strongly interacting flat band systems but also lead to new techniques for harnessing flat-band physics in future micro- and nano-scale devices.

This Special Issue aims at presenting state-of-the-art articles on both the theoretical and experimental studies within the umbrella of flat band physics.

In this Special Issue, original research articles and reviews are welcome. Research areas may include (but are not limited to) the following:

  • Strongly correlated spin, electronic and bosonic systems with flat bands;
  • Finetuning and perturbations of flat bands;
  • Flat bands and disorder/nonlinearity;
  • Flat bands and non-Hermitian;
  • Flat bands and topology;
  • Novel experimental platforms;
  • Flat bands and applications.
 

Dr. Liqin Tang
Dr. Shiqiang Xia
Guest Editors

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Keywords

  • strongly correlated spin, electronic and bosonic systems with flat bands
  • finetuning and perturbations of flat bands
  • flat bands and disorder/nonlinearity
  • flat bands and non-hermitian
  • flat bands and topology
  • novel experimental platforms
  • flat bands and applications

Published Papers (2 papers)

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Research

12 pages, 756 KiB  
Article
Flat Bands in Network Superstructures of Atomic Chains
by Donghyeok Heo, Junseop Lee, Anwei Zhang and Jun-Won Rhim
Photonics 2023, 10(1), 29; https://doi.org/10.3390/photonics10010029 - 27 Dec 2022
Viewed by 1872
Abstract
We investigate the origin of the ubiquitous existence of flat bands in the network superstructures of atomic chains, where one-dimensional (1D) atomic chains array periodically. While there can be many ways to connect those chains, we consider two representative ways of linking them, [...] Read more.
We investigate the origin of the ubiquitous existence of flat bands in the network superstructures of atomic chains, where one-dimensional (1D) atomic chains array periodically. While there can be many ways to connect those chains, we consider two representative ways of linking them, the dot-type and triangle-type links. Then, we construct a variety of superstructures, such as the square, rectangular, and honeycomb network superstructures with dot-type links and the honeycomb superstructure with triangle-type links. These links provide the wavefunctions with an opportunity to have destructive interference, which stabilizes the compact localized state (CLS). In the network superstructures, there exist multiple flat bands proportional to the number of atoms of each chain, and the corresponding eigenenergies can be found from the stability condition of the compact localized state. Finally, we demonstrate that the finite bandwidth of the nearly flat bands of the network superstructures arising from the next-nearest-neighbor hopping processes can be suppressed by increasing the length of the chains consisting of the superstructures. Full article
(This article belongs to the Special Issue Flat Bands: Fundamentals and Applications)
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18 pages, 5229 KiB  
Article
Optical Pattern Formation in a Rydberg-Dressed Atomic Gas with Non-Hermitian Potentials
by Zeyun Shi, Lu Qin, Xingdong Zhao and Haibo Huang
Photonics 2022, 9(11), 856; https://doi.org/10.3390/photonics9110856 - 11 Nov 2022
Cited by 1 | Viewed by 1284
Abstract
Spontaneous pattern formation from a spatially homogeneous background of nonlinear systems driven out of equilibrium is a widespread phenomenon in nature. However, similar phenomena and their physical realization in nonlinear systems with external potentials of gain and loss remain a challenge. We propose [...] Read more.
Spontaneous pattern formation from a spatially homogeneous background of nonlinear systems driven out of equilibrium is a widespread phenomenon in nature. However, similar phenomena and their physical realization in nonlinear systems with external potentials of gain and loss remain a challenge. We propose a scheme to realize a new type of spatial pattern formation through the self-organization of laser light in a Rydberg-dressed atomic gas with self-defocusing Kerr nonlinearity as well as non-Hermitian optical potentials. We show that by a suitable design of control and assistant laser fields, non-Hermitian optical potentials with or without parity-time (PT) symmetry for the probe laser field can be created. We find that through the nonlocal Kerr nonlinearity contributed by the long-range atom–atom interaction, a constant-intensity wave (CIW) may undergo modulation instability and induce spontaneous symmetry breaking, resulting in the emergence of various self-organized optical structures, which can be actively manipulated by tuning the nonlocality degree of the Kerr nonlinearity and by designing the non-Hermitian optical potentials. The results reported here open a door for developing non-Hermitian nonlinear optics. Full article
(This article belongs to the Special Issue Flat Bands: Fundamentals and Applications)
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