  Effect of quantum fluctuations concerned with the orbital degrees of freedom
is discussed for the model with SU(4) symmetry in one dimension. An effective
Hamiltonian is derived from the orbitally degenerate Hubbard model at quarter
filling. This model is equivalent to the Bethe soluble SU(4) exchange model.
Quantum numbers of the ground state and the lowest branch of excitations are
determined. The spin-spin correlation functions are obtained numerically by the
density matrix renormalization group method. It shows a power-law decay with
oscillations of the period of four sites. The period originates from the
interference between the spin and orbital degrees of freedom. The exponent of
the power-law decay estimated from the finite size data is consistent with the
prediction by the conformal field theory.
