Correlation length of the two-dimensional Ising spin glass with bimodal interactions

We study the correlation length of the two-dimensional Edwards-Anderson Ising spin glass with bimodal interactions using a combination of parallel tempering Monte Carlo updates and a rejection-free cluster algorithm in order to speed up equilibration. Our results show that the correlation length grows similar to exp(2J/T) suggesting through hyperscaling that the degenerate ground state is separated from the first excited state by an energy gap similar to 4J, as would naively be expected.