Wednesday, February 24, 2016

What is the value of the following commutator containing the spin 1/2 operators; [[S_x*S_y,S_y],S_z]?

Remember the definition of the commutation relation
[a,b]=ab-ba
Preform this operation on [S_x*S_y,S_y]
[[S_x*S_y,S_y],S_z]=[[S_x*S_y*S_y-S_y*S_x*S_y,S_z]
The following is the commutation relation for spin 1/2 systems.
[S_x,S_y]=i barh S_z
For cyclic permutations of x , y , and z . barh is represents the reduced planks constant here.
=[[S_x,S_y]S_y,S_z]
=[i barh S_z*S_y,S_z]
=i barh S_z[S_y,S_z]
=-barh^2S_z*S_x
http://easyspin.org/documentation/spinoperators.html

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