The Fermi-Hubbard model is an iconic model of solid state physics that is believed to capture the intricate physics of strongly correlated phases of matter such as High-Tc superconductivity. Such a state of matter is supposedly achieved upon doping a cold antiferromagnetic Mott insulator. Pairing of dopants (holes), in particular, is considered to be a key mechanism for the occurrence of unconventional superconductivity.
Here, I will present our experimental observation of hole pairing due to magnetic correlations in a Fermi-Hubbard-type system in our Lithium quantum-gas microscope. We engineer mixed-dimensional Fermi-Hubbard two-leg ladders in which a potential offset between the legs suppresses the tunneling along the rungs, while enhancing spin exchange and singlet formation, thus drastically increasing the hole binding energy. We observe in particular that holes preferably sit on the same rung in order to maintain magnetic ordering, and we extract a binding energy on the order of the spin exchange energy. We furthermore find indications for repulsion between pairs when there are several hole pairs in the system.
|Presenter name||Thomas Chalopin|