Observation of enhanced rotational symmetry breaking at low temperatures in the doped Hubbard model

The behavior of the doped Hubbard model at low temperatures is a central problem in correlated electron physics, with relevance to understanding cuprate superconductors. Extensive computational studies have shown that its low-temperature physics is governed by several competing symmetry-breaking tendencies, such as the loss of rotational or translational symmetry. However, the physics of these states remains poorly understood due to the computational challenges in simulating temperatures T<0.2t with standard techniques. Building on recent experimental progress in cooling in Fermi-Hubbard quantum simulators, we report the observation of a region of enhanced rotational symmetry breaking in the spin sector at temperatures T~0.1t. Using programmable potentials and tunable interactions, we study the evolution of this regime vs doping, temperature, and interaction strength. This work signals the emergence of novel physics at low temperatures in the Hubbard model, and demonstrates the approach of quantum simulation to a physical regime that challenges modern computational techniques.