PAIRING CORRELATIONS IN A 2-LAYER HUBBARD-MODEL

Superconducting properties of coupled Hubbard planes are studied by qu antum Monte Carlo simulations. It is found that the interlayer couplin g supports the pairing mechanism but it does not lead to off-diagonal long-range order in the purely electronic system. In addition, we have performed Monte Carlo studies based on a recently proposed variationa l wave function. Yielding identical results, the variational wave func tion overcomes the sign problem and allows us to analyze ground-state properties of strongly correlated many-body problems for system sizes and complexities not accessible otherwise.