发表机构
Stanford University; SLAC National Accelerator Laboratory（斯坦福大学; SLAC国家加速器实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过量子蒙特卡洛模拟，发现吸引与排斥Hubbard模型在强耦合下均表现出线性温度依赖电阻率，表明非相干输运对低能关联微观本质不敏感，仅在低温配对形成时出现分化。
AI 中文摘要
利用行列式量子蒙特卡洛模拟，我们在强耦合$|U|/t=6$下比较了二维吸引与排斥Hubbard模型的电荷输运性质。尽管相反符号的相互作用产生了定性不同的低能自旋、电荷和配对关联，两者在宽泛的中高温区间均表现出近似线性的电阻率随温度变化关系。在渐近高温下，这种共同行为源于电导率的矩展开，其主导贡献在$U$下为偶函数。更引人注目的是，这种相似性持续到远低于$|U|$的温度，此时强相互作用依赖的关联已经形成，且无论电阻率是否跨越MIR极限均成立。利用能斯特-爱因斯坦关系，我们发现共同的线性温度依赖电阻率主要与近似居里型的电荷压缩率和弱温度依赖的扩散率相关。两个模型仅在更低温度下出现分化，此时吸引模型在电荷扩散率中发展出与配对形成迹象相关的显著特征。这些结果表明，Hubbard模型中线性温度依赖的非相干输运对低能关联的微观本质可以极为不敏感。我们的结果提示，非相干区间的输运似乎对系统在低温下最终演变成的状态不敏感；竞争性低能态之间的区别仅当其特征关联获得足够长的空间或时间相干性时才变得可见。
英文摘要
Using determinant quantum Monte Carlo simulations, we compare charge transport in the two-dimensional attractive and repulsive Hubbard models at strong coupling, $|U|/t=6$. Although the interaction with opposite signs generates qualitatively different low-energy spin, charge, and pairing correlations, both exhibit approximately linear-in-temperature resistivity over a broad intermediate- and high-temperature regime. At asymptotically high temperature this common behavior follows from the moment expansion of the conductivity, whose leading contribution is even in $U$. More strikingly, the similarity persists to temperatures well below $|U|$, where strong interaction-dependent correlations have already developed, and also irrespective of whether resistivity crosses the MIR limit. Using the Nernst--Einstein relation, we find that the common linear-in-temperature resistivity is primarily associated with an approximately Curie-like charge compressibility and weakly temperature-dependent diffusivity. The two models separate only at lower temperatures, where the attractive model develops a pronounced feature in the charge diffusivity correlated with signatures of pair formation. These results show that linear-in-temperature incoherent transport in the Hubbard model can be remarkably insensitive to the microscopic nature of the low-energy correlations. Our results suggest that transport in the incoherent regime appears insensitive to what the system will ultimately become at low temperature; the distinction between competing low-energy states becomes visible only when their characteristic correlations acquire sufficiently long spatial or temporal coherence.
