Interaction-Enhanced Group Velocity of Bosons in the Flat Band of an Optical Kagome Lattice
Interaction-Enhanced Group Velocity of Bosons in the Flat Band of an Optical Kagome Lattice
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DOI：
10.1103/physrevlett.125.133001
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发表时间：
2020-09-21
影响因子：
8.6
通讯作者：
Stamper-Kurn, Dan
中科院分区：
文献类型：
--
作者：
Leung, Tsz-Him;Schwarz, Malte N.;Stamper-Kurn, Dan
Kagome 晶格中粒子运动的几何挫败导致单粒子能带结构具有平坦的 s 轨道带。我们通过将玻色-爱因斯坦凝聚态置于光学戈薇晶格的激发布洛赫态中来探测这种能带结构，然后通过原子动量分布测量群速度。我们发现相互作用使能带结构重新正常化，大大增加了第三能带的色散，这在单粒子处理中几乎是非色散的。基于晶格 Gross-Pitaevskii 方程的计算表明，能带结构重整化是由于相互作用导致整体晶格势远离 kagome 几何形状而引起的。
Geometric frustration of particle motion in a kagome lattice causes the single-particle band structure to have a flat s-orbital band. We probe this band structure by placing a Bose-Einstein condensate into excited Bloch states of an optical kagome lattice, and then measuring the group velocity through the atomic momentum distribution. We find that interactions renormalize the band structure, greatly increasing the dispersion of the third band, which is nearly non-dispersing the single-particle treatment. Calculations based on the lattice Gross-Pitaevskii equation indicate that band structure renormalization is caused by the distortion of the overall lattice potential away from the kagome geometry by interactions.