Flat Bands in Magic-Angle Bilayer Photonic Crystals at Small Twists

Area of Science:

• Photonics
• Condensed Matter Physics
• Materials Science

Background:

• Magic-angle twisted bilayer graphene (TBG) revealed novel physics in flat bands within moiré superlattices.
• Photonic counterparts of these flat bands are explored for applications like Bose-Einstein condensation.
• The relationship between photonic flat bands and bilayer photonic moiré systems is not well understood.

Purpose of the Study:

• To explore the correlation between photonic flat bands and bilayer photonic moiré systems.
• To investigate the potential of twisted bilayer honeycomb photonic crystals as an analogue to TBG.
• To discover and characterize magic-angle photonic flat bands and their properties.

Main Methods:

• Formulation of a coupled-mode theory for low-angle twisted bilayer honeycomb photonic crystals.
• Analogy drawn between the photonic system and twisted bilayer graphene (TBG).
• Construction of a phase diagram to map twist angle and interlayer separation dependencies.

Main Results:

• Discovery of magic-angle photonic flat bands with non-Anderson-type localization.
• Demonstration that interlayer separation is a tunable parameter for photonic moiré bands.
• Identification of photonic magic angles through a comprehensive phase diagram.

Conclusions:

• A strong correspondence exists between fermionic and bosonic moiré systems.
• The findings pave the way for advanced photonic band and state engineering.
• This research advances the development of moiré photonics and its applications.