Dimensional Crossover by a Local Inhomogeneity in Soliton-Pair Nucleation

Soliton-pair nucleation rates Gamma = A exp(-B) are studied in highly-biased sine-Gordon systems with a local inhomogeneity for both a thermal activation regime and a quantum tunneling regime. It is found that the local inhomogeneity strongly affects the nucleation rates by modifying the bias-dependence of the exponent B. This change in the exponent B is explained as a dimensional crossover caused by the local inhomogeneity. It is also shown that there is another crossover, at which A becomes independent of the system size.