Mobile small bipolarons on a three-dimensional cubic lattice
  We use numerically exact quantum Monte Carlo (QMC) to compute the properties of three-dimensional bipolarons for interaction strengths where perturbation theory fails. For intermediate electron-phonon coupling and Hubbard U, we find that bipolarons can be both small and light, a prerequisite for bipolaron superconductivity. We use the QMC results to make estimates of transition temperatures, which peak at between 90-120 K and are demonstrated to be insensitive to Coulomb repulsion and impurities. 
A. R. Davenport, J. P. Hague and P. E. Kornilovitch
cond-mat.str-el cond-mat.supr-con