论文标题
相关的金属两粒子结合状态在瓦尼尔 - 稳定的平板
Correlated metallic two-particle bound states in Wannier--Stark flatbands
论文作者
论文摘要
在空间尺寸中的简单勇敢晶格上的紧密结合单粒子模型$ d \ geq 2 $，当暴露于相称的直流场时，由于形成了Wannier-stark-stark Flatbands [Phys [Phys]，因此完全没有运输。 Rev. Res。 $ \ textbf {3} $，013174（2021）]。单粒子状态以阶乘方式定位，即比指数快。在这里，我们引入了两个这样的粒子之间的相互作用，它们部分提高了定位，并导致金属两粒子结合的状态在垂直于直流场的方向传播。我们使用与哈伯德相互作用的方形晶格证明了这种效果。我们将扰动理论应用于相互作用强度$（u）$ $ \ ll $跳高强度$（t）$ $ \ ll $ field offer $（\ Mathcal {F}）$（\ ll $ \ ll $）$（\ Mathcal {f}）$，并获得沿势力垂直方向的界限的组速度的估计。两粒子组速度缩放为$ u {（T/\ Mathcal {f}）}^ν$。我们计算指数$ν$在直流场方向以及与不受干扰的平带选择相关的主要两粒子配置上的依赖性。数值模拟从扰动分析中证实了我们的预测。
Tight-binding single-particle models on simple Bravais lattices in space dimension $d \geq 2$, when exposed to commensurate DC fields, result in the complete absence of transport due to the formation of Wannier--Stark flatbands [Phys. Rev. Res. $\textbf{3}$, 013174 (2021)]. The single-particle states localize in a factorial manner, i.e., faster than exponential. Here, we introduce interaction among two such particles that partially lifts the localization and results in metallic two-particle bound states that propagate in the directions perpendicular to the DC field. We demonstrate this effect using a square lattice with Hubbard interaction. We apply perturbation theory in the regime of interaction strength $(U)$ $\ll$ hopping strength $(t)$ $\ll$ field strength $(\mathcal{F})$, and obtain estimates for the group velocity of the bound states in the direction perpendicular to the field. The two-particle group velocity scales as $U {(t/\mathcal{F})}^ν$. We calculate the dependence of the exponent $ν$ on the DC field direction and on the dominant two-particle configurations related to the choices of unperturbed flatbands. Numerical simulations confirm our predictions from the perturbative analysis.
