Inthispaper,wetreatedquantumlogicgateasquantummechanicssystemandstudiedHamiltonianandmatrixrepresentationofunitarytransitioninthequantumlogicgate.Theconsistenceofinput(output)statesofquantumlogicgatesandwavefunctionsofquantummechanicssystemsareobtained.Thesewillbeusefulformakingchoiceoftwostatesystemstoimplementquantumlogicoperation.