  By utilizing the nondegenerate optical parametric amplifier, the quantum
state transfer from a pump state with high frequency to a signal state of lower
frequency is studied theoretically. The noiseless state transfer is
characterized by frequency conversion efficiency and noise figure. It is shown
that the quantum state can be well preserved during the frequency conversion as
long as the optical parametric amplifier is operated far below the threshold,
and meanwhile injected with an input idler field with a power density about ten
times greater than that of the pump. The dependence of the noise figure and
conversion efficiency on the idler amplitude, the analyzing frequency and the
cavity extra loss is also discussed.
