  We consider a mesoscopic normal metal, where the spin degeneracy is lifted by
a ferromagnetic exchange field or Zeeman splitting, coupled to two
superconducting reservoirs. As a function of the exchange field or the distance
between the reservoirs, the supercurrent through this device oscillates with an
exponentially decreasing envelope. This phenomenon is similar to the tuning of
a supercurrent by a non-equilibrium quasiparticle distribution between two
voltage-biased reservoirs. We propose a device combining the exchange field and
non-equilibrium effects, which allows us to observe a range of novel phenomena.
For instance, part of the field-suppressed supercurrent can be recovered by a
voltage between the additional probes.
