Exploring pseudogap physics with a neutral-atom Hubbard quantum simulator in the cryogenic regime (Precision Many Body Physics Focus session)

Understanding doped Mott insulators remains a central challenge in condensed-matter physics, underlying phenomena ranging from anomalous metals to high-temperature superconductivity. Ultracold fermionic atoms in optical lattices provide pristine realizations of the Hubbard model, yet until recently their achievable temperatures have remained above the regime where the most enigmatic phases emerge. In this talk, I will present a several-fold reduction in temperature in large-scale Hubbard-model quantum simulations, enabled by dynamically transforming low-entropy product states into strongly correlated states of interest. This advance brings the system to temperatures where long-range antiferromagnetism is nearly saturated at half-filling, and—crucially—into a regime of doped Hubbard physics that can not yet be reliably simulated via classical computation.

Leveraging these ultralow temperatures, we perform thermodynamic and spectroscopic measurements that reveal a crossover between a normal metal and a pseudogapped metal in the Fermi-Hubbard model. Compressibility measurements uncover a line of thermodynamic anomalies that separates an underdoped from an overdoped metal at strong interactions. Lattice-modulation spectroscopy shows a momentum-dependent loss of low-energy spectral weight on the underdoped side, allowing us to map out a pseudogap phase diagram across interaction strength and doping. The observed pseudogap, its relation to spin and charge correlations, and its connection to cuprate phenomenology together demonstrate that the Hubbard model hosts a pseudogapped metallic state and suggest links to incipient charge order.

These results showcase how quantum simulation can now reach the temperatures, scales, and observables required to confront long-standing open problems in correlated electron physics, create new synergies with state-of-the-art numerical methods, and potentially illuminate the mechanisms underlying high-temperature superconductivity.