Theory of time-correlated tunneling of density wave solitons

Abstract
We discuss a model in which an applied field induces quantum nucleation of soliton-antisoliton (S-S') pairs in a pinned charge or spin density wave. Coulomb blockade prevents pair creation until the electric field exceeds a sharp threshold value, which can be much smaller than the classical depinning field. Above threshold, the pair creation events become correlated in time, by analogy to time-correlated single electron tunneling. We compute the phase polarization and find that, depending on parameters, the predicted phase polarization can either be extremely small below threshold, as observed in NbSe₃, or quite substantial, as observed in blue bronze. The lack of significant phase polarization below threshold in NbSe₃, indicated by several experiments, suggests that the measured threshold field is a quantum S-S' pair creation threshold rather than a classical depinning field.