  We propose a general design of a metallic double-nanowire structure which may
support an equilibrium dissipationless electric current in the presence of
magnetic field. The structure consists of a compact wire element of a specific
shape, which is periodically extended in one spatial dimension. Topologically,
each wire element is equivalent to a ring, which supports a dissipationless
current in the presence of magnetic flux similarly to the persistent electric
current in a normal metal nanoring. Geometrically, each wire element breaks
spatial inversion symmetry so that the equilibrium electric current through the
device becomes nonzero. We also argue that the same effect should exist in long
planar chiral nanoribbons subjected to external magnetic field.
