Problem 1 [4]
For ℓ = 1, the angular-momentum components ˆLx, ˆLy and ˆLz are represented by the
matrices
Lx =
0 ℏ/√2 0
ℏ/√2 0 ℏ/√2
0 ℏ/√2 0
Ly =
0 −iℏ/√2 0
iℏ/√2 0 −iℏ/√2
0 iℏ/√2 0
Lz =
ℏ 0 0
0 0 0
0 0 −ℏ
,
(i) Compute L2 = L2
x + L2
y + L2
z and show that it is a multiple of the identity matrix.
(ii) Compute the eigenvalues of Lx and Ly.
(iii) Show that
1
0
1
is an eigenvector of Ly . If a system is in this state, what are the
probabilities for finding the values ℏ, 0, and −ℏ, respectively, in a single measurement
of Lz ?