论文标题
具有可调量子度量的平坦带中的超导性，电荷密度波和超压相
Superconductivity, charge density wave, and supersolidity in flat bands with tunable quantum metric
论文作者
论文摘要
在电子带宽被淬灭的情况下，预测相互作用系统的命运通常是高度不平凡的。相互作用和由带状几何形状驱动的量子波动之间的复杂相互作用可以推动各种基态之间的竞争，例如电荷密度波顺序和超导性。在这项工作中，我们使用数值精确的量子蒙特卡洛模拟，研究了具有连续可调的fubini-study指标的拓扑平坦带的电子模型。通过改变电子填充和局部平板浮游波函数的最小空间范围，我们获得了许多相互交织的顺序。这些包括具有共存电荷密度波（CDW）和超导性的相位相位，即超olid。尽管问题的非扰动性质，但我们确定了与Wannier函数的“小”空间范围相关的可分析性障碍极限，并得出了低能的有效哈密顿量，可以很好地描述我们的数值结果。我们还提供了明确的证据，证明违反了在几何非平凡的平坦波段中对零温度超流体刚度的任何推定下限。
Predicting the fate of an interacting system in the limit where the electronic bandwidth is quenched is often highly non-trivial. The complex interplay between interactions and quantum fluctuations driven by the band geometry can drive competition between various ground states, such as charge density wave order and superconductivity. In this work, we study an electronic model of topologically-trivial flat bands with a continuously tunable Fubini-Study metric in the presence of on-site attraction and nearest-neighbor repulsion, using numerically exact quantum Monte Carlo simulations. By varying the electron filling and the minimal spatial extent of the localized flat-band Wannier wavefunctions, we obtain a number of intertwined orders. These include a phase with coexisting charge density wave (CDW) order and superconductivity, i.e., a supersolid. In spite of the non-perturbative nature of the problem, we identify an analytically tractable limit associated with a 'small' spatial extent of the Wannier functions and derive a low-energy effective Hamiltonian that can well describe our numerical results. We also provide unambiguous evidence for the violation of any putative lower bound on the zero-temperature superfluid stiffness in geometrically non-trivial flat bands.
