  Recent progress in optically trapped ultracold atomic gases is now making it
possible to access microscopic observables in doped Mott insulators, which are
the parent states of high-temperature superconductors. This makes it possible
to address longstanding questions about the temperature scales at which
attraction between charge carriers are present, and their mechanism.
Controllable theoretical results for this problem are not available at low
temperature due to the sign problem. In this work, we employ worm-algorithm
Monte Carlo to obtain completely unbiased results for two charge carriers in a
Mott insulator. Our method gives access to lower temperatures than what is
currently possible in experiments, and provides evidence for attraction between
dopants at a temperature scale that is now feasible in ultracold atomic
systems. We also report on spin-correlations in the presence of charge
carriers, which are directly comparable to experiments.
