Helical states and solitons in noncentrosymmetric superconductors

We show how the two-band nature of superconductivity in noncentrosymmetric compounds leads to a variety of different nonuniform superconducting states induced by a magnetic field. At low fields, a two-band helical state is realized, with a distinctly non-BCS quasiparticle spectrum. At high fields, the superconducting state becomes unstable towards the formation of a lattice of topological phase solitons.