Physical review. B./Physical review. B
Probing a modified Luttinger sum rule in the strongly interacting one-dimensional Fermi-Hubbard model
Annika Böhler, Henning Schlömer, Ulrich Schollwöck, Annabelle Bohrdt, Fabian Grusdt
Abstract
Fermi surface reconstruction in cuprates can lead to an abrupt change in the Fermi momentum ${k}_{F}$ between different phases. This phenomenon remains a subject of debate and is at the heart of an ongoing discussion about the nature of the metallic state in the pseudogap regime. Here we study a minimal model of a ${k}_{F}$ changing crossover in the one-dimensional Fermi-Hubbard model, where a tuning of the on-site interaction leads to a crossover between a spin-$1/2$ Luttinger liquid with small Fermi momentum and a spinless chargon liquid with large Fermi momentum. We attribute this to an emergent $U(1)$ symmetry in the strongly correlated limit, which can be used to derive a modified Luttinger sum rule recovering the large Fermi momentum. We analyze Friedel oscillations at the edge of a system to directly probe the change of Fermi momentum at zero and nonzero temperature. This paves the way for a direct experimental observation of changes of the Fermi momentum using ultracold fermions in a quantum gas microscope, with possible extensions to higher dimensional systems.