Theory of time-correlated tunneling of density wave solitons

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. C oulomb blockade prevents pair creation until the electric field exceeds a s harp threshold value, which can be much smaller than the classical depinnin g field. Above threshold, the pair creation events become correlated in tim e, by analogy to time-correlated single electron tunneling. We compute the phase polarization and find that, depending on parameters, the: predicted p hase polarization can either be extremely small below threshold, as observe d in NbSe3, or quite substantial, as observed in blue bronze. The lack of s ignificant phase polarization below threshold in NbSe3, indicated by severa l experiments, suggests that the measured threshold field is a quantum S-S' pair creation threshold rather than a classical depinning field.