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To the Hubbard model on a square lattice we add an interaction, W , which depends upon the square of a near-neighbor hopping. We use zero temperature quantum Monte Carlo simulations on lattice sizes up to 16 × 16, to show that at half-filling and constant value of the Hubbard repulsion, the interaction W triggers a quantum transition between an antiferromagnetic Mott insulator and a d x 2 −y 2 superconductor. With a combination of finite temperature quantum Monte Carlo simulations and the Maximum Entropy method, we study spin and charge degrees of freedom in the superconducting state. We give numerical evidence for the occurrence of a finite temperature Kosterlitz-Thouless transition to the d x 2 −y 2 superconducting state. Above and below the Kosterlitz-Thouless transition temperature, T KT , we compute the one-electron density of states, N (ω), the spin relaxation rate 1/T 1 , as well as the imaginary and real part of the spin susceptibility χ( q, ω). The spin dynamics are characterized by the vanishing of 1/T 1 and divergence of Reχ( q = (π, π), ω = 0) in the low temperature limit. As T KT is approached N (ω) develops a pseudo-gap feature and below T KT Imχ( q = (π, π), ω) shows a peak at finite frequency.

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We consider a Hubbard model on a square lattice with an additional interaction, W , which depends upon the square of a near-neighbor hopping. At half-filling and a constant value of the Hubbard repulsion, increasing the strength of the interaction W drives the system from an antiferromagnetic Mott insulator to a d x 2 −y 2 superconductor. This conclusion is reached on the basis of zero temperature quantum Monte Carlo simulations on lattice sizes up to 16 × 16.

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