Ameliorating the sign problem for frustrated magnets using plaquette grouping

Frustrated quantum magnets are not amenable to simulation using conventional quantum Monte Carlo because of the infamous sign problem. In the overcomplete basis of singlet product states, updates have a many-to-one property that allows for grouping of updates around plaquettes in such a way that the negative sampling weights are almost entirely eliminated. Results for the J1-J2 quantun Heisenberg model on the square lattice are discussed.