  We consider a one-dimensional superconducting wire where the total number of
electrons can be controlled in the Coulomb blockade regime. We predict that a
pi soliton (kink) will spontaneously form in the system when the number of
electron is odd, because this configuration has a lower energy. If the wire
with an odd number of electrons is closed in a ring, the phase difference on
the two sides of the soliton will generate a supercurrent detectable by SQUID.
The two degenerate states with the current flowing clockwise or
counterclockwise can be utilized as a qubit.
