  We show that sine-Gordon solitons appear in the low-energy effective theory
of a domain wall in a U(1) gauge theory with two charged complex scalar fields
with masses, if we introduce the Josephson interaction term between the scalar
fields. We identify these sine-Gordon solitons as vortices or CP(1) sigma model
instantons in the bulk, which are absorbed into the domain wall world-volume.
These vortices can be called as Josephson vortices since they appear in
Josephson junctions of two superconductors. This set up gives a physical
realization of a lower dimensional analogue of Atiyah-Manton construction of
Skyrmions from instanton holonomy.
