Direct observation of nonlocal fermion pairing in an attractive Fermi-Hubbard gas

• 成果类型: Article
• 署名作者: Hartke, Thomas; Oreg, Botond; Turnbaugh, Carter; Jia, Ningyuan; Zwierlein, Martin
• 署名单位: Massachusetts Institute of Technology (MIT); Massachusetts Institute of Technology (MIT)
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8433
• DOI: 10.1126/science.ade4245
• 发表日期: 2023-07-07
• 页码: 82-+
• 关键词: phase-diagram; superconductivity; crossover; condensation; EVOLUTION; state

摘要

The Hubbard model of attractively interacting fermions provides a paradigmatic setting for fermion pairing. It features a crossover between Bose-Einstein condensation of tightly bound pairs and Bardeen-Cooper-Schrieffer superfluidity of long-range Cooper pairs, and a pseudo-gap region where pairs form above the superfluid critical temperature. We directly observe the nonlocal nature of fermion pairing in a Hubbard lattice gas, using spin- and density-resolved imaging of similar to 1000 fermionic potassium-40 atoms under a bilayer microscope. Complete fermion pairing is revealed by the vanishing of global spin fluctuations with increasing attraction. In the strongly correlated regime, the fermion pair size is found to be on the order of the average interparticle spacing. Our study informs theories of pseudo-gap behavior in strongly correlated fermion systems.