Atomic Bose–Einstein condensate in twisted-bilayer optical lattices
Atomic Bose–Einstein condensate in twisted-bilayer optical lattices
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DOI：
10.1038/s41586-023-05695-4
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发表时间：
2021-10
期刊：
影响因子：
64.8
通讯作者：
Zengming Meng;Liang-Liang Wang-Liang;Weifang Han;Fangde Liu;K. Wen;Chao Gao;Pengjun Wang;C. Chin;Jing Zhang
中科院分区：
文献类型：
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作者：
Zengming Meng;Liang-Liang Wang-Liang;Weifang Han;Fangde Liu;K. Wen;Chao Gao;Pengjun Wang;C. Chin;Jing Zhang
在扭曲双层石墨烯中观察到的强关联和超导性，激发了人们对基础物理和应用物理的极大兴趣。在这个系统中，两个扭曲的蜂窝晶格的叠加，产生莫尔图案，是观察到平坦的电子带，慢电子速度和大的态密度的关键。扭曲双层系统的扩展到新的配置是非常期望的，这可以提供令人兴奋的前景，研究双电子超越双层石墨烯。在这里，我们展示了一个量子模拟的超流莫特绝缘体过渡的扭曲双层正方形晶格的基础上加载到自旋相关的光学晶格的原子玻色-爱因斯坦凝聚。晶格由两组激光束组成，它们独立地寻址处于不同自旋状态的原子，从而形成容纳两层的合成维度。层间耦合是高度可控的微波场，这使得最低的平带和新的相关相位的发生在强耦合限制。我们直接观察到的空间云纹图案和动量衍射，这证实了存在两种形式的超流和修改的超流到绝缘体的扭转双层晶格的转变。我们的计划是通用的，可以应用到不同的晶格几何形状和玻色子和费米子系统。这为在具有高度可控光学晶格的超冷原子中探索莫尔物理开辟了新的方向。
Observation of strong correlations and superconductivity in twisted-bilayer graphene, , –has stimulated tremendous interest in fundamental and applied physics, , –. In this system, the superposition of two twisted honeycomb lattices, generating a moiré pattern, is the key to the observed flat electronic bands, slow electron velocity and large density of states, , –. Extension of the twisted-bilayer system to new configurations is highly desired, which can provide exciting prospects to investigate twistronics beyond bilayer graphene. Here we demonstrate a quantum simulation of superfluid to Mott insulator transition in twisted-bilayer square lattices based on atomic Bose–Einstein condensates loaded into spin-dependent optical lattices. The lattices are made of two sets of laser beams that independently address atoms in different spin states, which form the synthetic dimension accommodating the two layers. The interlayer coupling is highly controllable by a microwave field, which enables the occurrence of a lowest flat band and new correlated phases in the strong coupling limit. We directly observe the spatial moiré pattern and the momentum diffraction, which confirm the presence of two forms of superfluid and a modified superfluid to insulator transition in twisted-bilayer lattices. Our scheme is generic and can be applied to different lattice geometries and for both boson and fermion systems. This opens up a new direction for exploring moiré physics in ultracold atoms with highly controllable optical lattices.