Flat Bands in Magic-Angle Bilayer Photonic Crystals at Small Twists
Flat Bands in Magic-Angle Bilayer Photonic Crystals at Small Twists
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DOI：
10.1103/physrevlett.126.223601
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发表时间：
2021-06-02
影响因子：
8.6
通讯作者：
Yao, Jie
中科院分区：
文献类型：
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作者：
Dong, Kaichen;Zhang, Tiancheng;Yao, Jie
魔角扭曲双层石墨烯（TBG）的新物理学推动了对范德华结构中莫尔超晶格所承载的平带的广泛研究，激发了对其光子对应物及其潜在应用（包括玻色-爱因斯坦凝聚）的研究。然而，光子平带和双层光子莫尔系统之间的相关性仍未得到探索，阻碍了莫尔光子学的进一步发展。在这项工作中，我们制定了低角度扭曲双层蜂窝光子晶体的耦合模式理论，作为 TBG 的紧密类比，发现了具有非安德森型局域化的魔角光子平带。此外，层间分离构成了无需高压即可调节光子莫尔带的方便自由度。构建相图以将扭转角和分离依赖性与光子魔角相关联。我们的研究结果揭示了费米子和玻色子云纹系统之间的显着对应关系，并为通过先进的光子带或态工程实现新的应用铺平了道路。
The new physics of magic-angle twisted bilayer graphene (TBG) motivated extensive studies of flat bands hosted by moire superlattices in van der Waals structures, inspiring the investigations into their photonic counterparts with potential applications including Bose-Einstein condensation. However, correlation between photonic flat bands and bilayer photonic moire systems remains unexplored, impeding further development of moire photonics. In this work, we formulate a coupled-mode theory for low-angle twisted bilayer honeycomb photonic crystals as a close analogy of TBG, discovering magic-angle photonic flat bands with a non-Anderson-type localization. Moreover, the interlayer separation constitutes a convenient degree of freedom in tuning photonic moire bands without high pressure. A phase diagram is constructed to correlate the twist angle and separation dependencies to the photonic magic angles. Our findings reveal a salient correspondence between fermionic and bosonic moire systems and pave the avenue toward novel applications through advanced photonic band or state engineering.