Please urgent help.[quantum] I have a homework I have tried a lot of thinks but I couldnot manage to solve. problem: for two particle j1 = 2 ; j2 = 1 and the condition is m=m1 + m2 = 2. by using Clebsch Gordan coefficients for the possible states !22> and !32>, create a matrix which will be a 2x2 matix lest say U and create j square for the system. find the matrix product U(transpose).j(square).U. I know that this pruduct will be the identity matris I if you take the h(bar) as 1 I have created the matrix U that is -squareroot(1/3) squareroot(2/3) squareroot(2/3) squareroot(1/3) but I have problem with the j(square) I know the j(square)= j1(square) + j2(square) + [(j1-.j2+) + (j1-.j2+)] + 2j1z.j2z here j1- and j2- are lowering and j1+ and j2+ are rising optrs. please someone help me with the building of j(square) matris. I really have done whatever I can do.