ARPES in Fermi-Hubbard Systems with Arbitrary Interactions

Cold atom realizations of the Fermi-Hubbard model in optical lattices have reached temperatures in the pseudogap regime [1,2]. Spectroscopic studies are particularly valuable in this regime, where they can teach us about the nature of the quasiparticles in the system and their dispersions. Angle-resolved photoemission spectroscopy (ARPES), a technique widely used in condensed matter physics for this purpose, has been challenging to implement in Hubbard systems. Effective photo-ejection of an atom from the system relies on transfer to a final state where interactions are negligible. This has been realized using radiofrequency spin flips for systems with attractive interactions, but the technique used cannot be easily extended to repulsive interactions [3]. In this work, we develop a novel ARPES technique that utilizes ejection to an unoccupied Hubbard miniband with negligible final state interactions. This enables the study of photoemission spectra at arbitrary interactions, including in doped Mott insulators.

[1] M. Xu et al., Nature 642, 909 (2025)

[2] T. Chalopin et al., arxiv:2412.17801 (2024)

[3] P. Brown et al., Nature Phys. 16, 26 (2020)