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arXiv · 2605.31240

Emergence of spin entanglement with the pseudogap onset in the Fermi-Hubbard model

Frederic Bippus·Thomas Chalopin·Gabriele Bellomia·Gergő Roósz·Titus Franz·Antoine Georges·Anna Kauch·Immanuel Bloch·Karsten Held
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Abstract

Despite decades of intense theoretical and experimental investigation, the two-dimensional Fermi-Hubbard model still resists a complete microscopic understanding. Conventional approaches typically probe global observables and locally resolved correlation functions. Here, we develop a complementary perspective based on the measurement of entanglement. Using both an ultracold-atom quantum simulator and numerical simulations based on the dynamical vertex approximation, we find that entanglement is closely tied to the onset of the enigmatic pseudogap regime: spin-singlet entanglement emerges only as the pseudogap sets in and, in contrast to classical correlations, remains confined to nearest-neighbour sites in this regime. Our results, therefore, disfavour purely classical-fluctuation theories of the pseudogap and constrain microscopic models to those that develop nearest-neighbour spin-singlet entanglement at the pseudogap onset.

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Frederic Bippus, Thomas Chalopin, Gabriele Bellomia, Gergő Roósz, Titus Franz, Antoine Georges, Anna Kauch, Immanuel Bloch, Karsten Held. 2026-05-29. Emergence of spin entanglement with the pseudogap onset in the Fermi-Hubbard model. https://arxiv.org/abs/2605.31240

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