Degeneracy-reshaped spin squeezing in high-spin Fermi-Hubbard systems weakly coupled to light

Abstract

We study spin squeezing in strongly interacting high-spin Fermi-Hubbard systems weakly coupled to light. We show that spin squeezing dynamics is qualitatively modified by the degeneracies associated with the internal spin structure. We identify these degeneracies as the microscopic origin of the breakdown of conventional maximal-spin description and develop an effective framework based on population eigenstates that quantitatively reproduces spin squeezing evolution. Our results uncover a generic mechanism by which degeneracy reshapes collective spin dynamics.