  This letter treats the quantum random walk on the line determined by a 2
times 2 unitary matrix U. A combinatorial expression for the mth moment of the
quantum random walk is presented by using 4 matrices, P, Q, R and S given by U.
The dependence of the mth moment on U and initial qubit state phi is clarified.
A new type of limit theorems for the quantum walk is given. Furthermore
necessary and sufficient conditions for symmetry of distribution for the
quantum walk is presented. Our results show that the behavior of quantum random
walk is striking different from that of the classical ramdom walk.
