  We have measured the shot noise in a quantum point contact (QPC) fabricated
by using InGaAs/InGaAsP heterostructure, whose conductance can be electrically
tuned by the gate voltages. The reduced shot noise is observed when the QPC
conductance equals to N(2e^2/h) (N=4, 5, and 6), which is the direct
experimental evidence of the coherent quantized channel formation in the QPC.
The deviation of the observed Fano factor from the theory is explained by the
electron heating effect generated at the QPC.
