How to Demonstrate [Lk, r^2] = 0?

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SUMMARY

The discussion focuses on demonstrating that the commutator [Lk, r^2] equals zero, where L represents angular momentum and r^2 is the square of the position vector. The participant clarifies that L can be expressed as L = r x p, with p being the momentum operator. The solution involves breaking down the commutator into three parts: [Lz, x^2], [Lz, y^2], and [Lz, z^2], which are to be calculated individually to confirm that their sum results in zero.

PREREQUISITES
  • Understanding of angular momentum operators in quantum mechanics
  • Familiarity with commutation relations
  • Knowledge of position and momentum operators
  • Basic grasp of vector calculus and cross products
NEXT STEPS
  • Study the derivation of angular momentum operators in quantum mechanics
  • Learn about commutation relations and their implications in quantum mechanics
  • Explore the properties of the position operator in quantum mechanics
  • Investigate the significance of the commutator in quantum mechanics
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Students and professionals in quantum mechanics, particularly those studying angular momentum and commutation relations, will benefit from this discussion.

jc09
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Homework Statement


Show that [ Lk , r^2] = 0


Homework Equations





The Attempt at a Solution


know that L=r x p=r x(-ih(bar)V)
 
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With the k I take it you mean the third component?

Lets write it like this [Lz,r^2]=[Lz,x^2+y^2+z^2]=[Lz,x^2]+[Lz,y^2]+[Lz,z^2]. Can you work out these three commutators?
 

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