Spin one operators.  Verify that all my corrections to Desai eq. (27.117) are correct.

ClearAll[ hb, Jx, Jy, Jz, Jxx, Jyy, Jzz] ;
hb = ℏ ;
Jx = {{0,1,0}, {1,0,1}, {0,1,0}} hb/Sqrt[2] ;
Jy = I{{0,-1,0}, {1,0,-1}, {0,1,0}} hb/Sqrt[2] ;
Jz = {{1,0,0}, {0,0,0}, {0,0,-1}} hb ;
Jx // TraditionalForm
Jy // TraditionalForm
Jz // TraditionalForm

(*squares are not unit matrices like the Pauli matrices*)
Jx . Jx / hb^2// TraditionalForm
Jy. Jy /hb^2 // TraditionalForm
Jz . Jz /hb^2 // TraditionalForm

(*expect eigenvalues :±ℏ, 0*)
Eigensystem[#] &/@ {Jx, Jy, Jz}

Jzz =(Jx . Jy - Jy . Jx)/ hb /I;
Jxx =(Jy . Jz - Jz . Jy) / hb /I ;
Jyy =(Jz . Jx - Jx . Jz) / hb / I ;
(*expect zeros:*)
Jxx - Jx // TraditionalForm
Jyy - Jy // TraditionalForm
Jzz - Jz // TraditionalForm