Superfluid transition temperature of bond bipolarons with Coulomb interaction

Utilizing an exactly sign-problem-free quantum Monte Carlo method, we explore the influence of long-range Coulomb interaction on the superfluid transition temperature of bipolarons in two dimensions. The model studied here is the bond Su-Schrieffer-Heeger model with phonon-modulated electron hopping. Previously, in the absence of long-range Coulomb interaction, this model demonstrated the emergence of small-size, light-mass bipolarons that undergo a superfluid transition at high values of the transition temperature Tc [Physical Review X 13, 011010, (2023)]. Our findings indicate that even with the inclusion of long-range Coulomb interaction, Tc remains substantially high, even in the deep adiabatic regime where the phonon frequency is ω/t = 0.5 and the Coulomb interaction $V = U/10$. This result suggests a physical mechanism for superconductivity in the low-density regime, which could hold relevance for ongoing experiments on dilute superconductors.