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arXiv 2204.12652cond-mat.quant-gascond-mat.mtrl-scicond-mat.str-elquant-ph
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Wannier-Stark平带中的关联金属两粒子束缚态

Correlated metallic two-particle bound states in Wannier--Stark flatbands

Arindam Mallick, Alexei Andreanov, Sergej Flach

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11 pages, 7 figures. Comments are welcome
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摘要：

当暴露于相称的DC场时，空间维度$d \geq 2$中简单布拉维晶格上的紧束缚单粒子模型由于形成Wannier-Stark平带而导致完全不存在输运[Phys. Rev. Res. $\textbf{3}$，013174（2021）]。单粒子态以阶乘方式局域化，即，比指数更快。在这里，我们引入两个这样的粒子之间的相互作用，部分解除本地化，并导致在垂直于DC场的方向上传播的金属两粒子束缚态。我们证明了这种效果，使用一个正方形晶格与哈伯德相互作用。我们应用微扰理论的相互作用强度$(U)$ $\ll$跳变强度$(t)$ $\ll$场强$(\mathcal{F})$的制度，并获得在垂直于该领域的方向上的束缚态的群速度的估计。两粒子群速度的标度为$U {(t/\mathcal{F})}^ν$。我们计算的指数$ν$上的DC场的方向上的依赖性和未微扰平带的选择有关的占主导地位的两个粒子的配置。数值模拟证实了我们的预测从微扰分析。

英文摘要：

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.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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