Schneider U, Hackermüller L, Will S, Best Th, Bloch I, Costi T A, Helmes R W, Rasch D, Rosch A
Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
Science. 2008 Dec 5;322(5907):1520-5. doi: 10.1126/science.1165449.
The fermionic Hubbard model plays a fundamental role in the description of strongly correlated materials. We have realized this Hamiltonian in a repulsively interacting spin mixture of ultracold (40)K atoms in a three-dimensional (3D) optical lattice. Using in situ imaging and independent control of external confinement and lattice depth, we were able to directly measure the compressibility of the quantum gas in the trap. Together with a comparison to ab initio dynamical mean field theory calculations, we show how the system evolves for increasing confinement from a compressible dilute metal over a strongly interacting Fermi liquid into a band-insulating state. For strong interactions, we find evidence for an emergent incompressible Mott insulating phase. This demonstrates the potential to model interacting condensed-matter systems using ultracold fermionic atoms.
费米子哈伯德模型在强关联材料的描述中起着基础性作用。我们在三维光学晶格中由超冷（40）K原子构成的排斥相互作用自旋混合物中实现了这种哈密顿量。通过原位成像以及对外部约束和晶格深度的独立控制，我们能够直接测量陷阱中量子气体的压缩性。结合与从头算动态平均场理论计算的比较，我们展示了随着约束增加，系统如何从可压缩的稀金属经过强相互作用费米液体演变为带绝缘态。对于强相互作用，我们发现了出现不可压缩莫特绝缘相的证据。这证明了使用超冷费米子原子对相互作用凝聚态系统进行建模的潜力。
