We have performed density-matrix renormalization group studies of a square lattice $t$-$J$ model with small hole doping, $deltall 1$, on long 4 and 6 leg cylinders. We include frustration in the form of a second-neighbor exchange coupling, $J_2 = J_1/2$, such that the undoped ($delta=0$) parent state is a quantum spin liquid. In contrast to the relatively short range superconducting (SC) correlations that have been observed in recent studies of the 6-leg cylinder in the absence of frustration, we find power law SC correlations with a Luttinger exponent, $K_{sc} approx 1$, consistent with a strongly diverging SC susceptibility, $chi sim T^{-(2-K_{sc})}$ as the temperature $Tto 0$. The spin-spin correlations - as in the undoped state - fall exponentially suggesting that the SC pairing correlations evolve smoothly from the insulating parent state.
تحميل البحث