We study the phenomenon of quantum creep in bulk superconductors within the framework of weak-collective-pinning theory. Single-vortex pinning at moderate magnetic fields as well as creep of vortex bundles at high fields are discussed for the case of current densities near critical. In the limit of strong dissipation and for moderate fields the basic parameter determining the tunneling rate is the ratio ${\mathrm{\rho }}_{\mathit{n}}$/ξ (${\mathrm{\rho }}_{\mathit{n}}$=normal-state resistivity, ξ=coherent length), with strong tunneling realized for ${\mathrm{\rho }}_{\mathit{h}}$/ξ≳1 kΩ.

• Received 25 February 1991

DOI:https://doi.org/10.1103/PhysRevLett.66.3297