  We find that, under certain condition, a quantum dot with odd number of
electron and coupled to two leads can be described by a non-equilibrium
2-channel Kondo model, when the two leads has a large voltage bias between
them. The model is exactly soluble and can be mapped into a free fermion
system, even in the presence of external magnetic field and other relevant
perturbations. All (dynamical) correlation functions can be calculated. The
fixed point of the 2-channel Kondo model is a non-equilibrium fixed point and
is different from the usual 1-channel and 2-channel Kondo fixed point.
