Quantum Monte Carlo simulations of infinitely strongly correlated fermions

Numerical simulations of the two-dimensional t-J model in the limit J/t much less than 1 are performed for rather large systems (N similar to 10x10) using a world-line loop algorithm. It is shown that in the one-hole case with J=0, very low temperatures (beta t similar to 2500) are necessary in order to reach Nagaoka's state. Full polarization becomes unstable for J similar to 10(-4)t towards partial polarization up to J/t less than or similar to 0.01. J/t greater than or similar to 0.05 leads to minimal spin. The two-hole case shows enhanced total spin up to the lowest attainable temperatures (beta t=150), well below those reached by other finite-temperature methods. [S0163-1829(98)52140-6].