Department of Physics, University of California, San Diego, California 92093, USA.
Condensed Matter Theory Center and Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
Phys Rev Lett. 2018 Oct 19;121(16):167205. doi: 10.1103/PhysRevLett.121.167205.
The interaction effects in ultracold Fermi gases with SU(N) symmetry are studied nonperturbatively in half filled one-dimensional lattices by employing quantum Monte Carlo simulations. We find that, as N increases, weak and strong interacting systems are driven to a crossover region, but from opposite directions as a convergence of itinerancy and Mottness. In the weak interaction region, particles are nearly itinerant, and interparticle collisions are enhanced by N, resulting in the amplification of interaction effects. In contrast, in the strong coupling region, increasing N softens the Mott-insulating background through the enhanced virtual hopping processes. The crossover region exhibits nearly N-independent physical quantities, including the relative bandwidth, Fermi distribution, and the spin structure factor. The difference between even-N and odd-N systems is most prominent at small N's with strong interactions, since the odd case allows local real hopping with an energy scale much larger than the virtual one. The above effects can be experimentally tested in ultracold atom experiments with alkaline-earth(-like) fermions such as ^{87}Sr (^{173}Yb).
通过量子蒙特卡罗模拟，我们非微扰地研究了超冷费米气体在具有 SU(N) 对称的半满一维晶格中的相互作用效应。我们发现，随着 N 的增加，弱相互作用和强相互作用系统都被推向了一个交叉区域，但由于巡游和莫特绝缘性的收敛方向相反。在弱相互作用区域，粒子几乎是巡游的，粒子间的碰撞被 N 增强，导致相互作用效应的放大。相比之下，在强耦合区域，通过增强的虚拟跃迁过程，N 的增加软化了莫特绝缘背景。交叉区域表现出几乎与 N 无关的物理量，包括相对带宽、费米分布和自旋结构因子。在具有强相互作用的小 N 情况下，偶数-N 和奇数-N 系统之间的差异最为明显，因为奇数情况允许具有比虚拟跃迁大得多的能量尺度的局部实跃迁。上述效应可以在具有碱性土（类）费米子如 ^{87}Sr（^{173}Yb）的超冷原子实验中进行实验验证。
