Do p and σz Commute?

  • Thread starter Thread starter Niles
  • Start date Start date
  • Tags Tags
    Commutator
Click For Summary
SUMMARY

The discussion centers on the commutation relationship between the momentum operator \( p \) and the third Pauli spin matrix \( \sigma_z \). Niles initially posits that they commute since they act on different spaces. However, further clarification reveals that if the momentum operator is defined as x-momentum and the spin as z-spin, they do not commute due to the implications of measuring x-momentum. Ultimately, it is established that \( p \) and \( \sigma_z \) do commute under specific conditions.

PREREQUISITES
  • Understanding of quantum mechanics principles
  • Familiarity with operators in quantum mechanics
  • Knowledge of Pauli matrices, specifically \( \sigma_z \)
  • Concept of commutation relations in quantum physics
NEXT STEPS
  • Study the implications of commutation relations in quantum mechanics
  • Learn about the role of momentum operators in quantum systems
  • Explore the properties of Pauli matrices and their applications
  • Investigate the measurement theory in quantum mechanics
USEFUL FOR

Students and professionals in quantum mechanics, physicists exploring operator theory, and anyone interested in the mathematical foundations of quantum systems.

Niles
Messages
1,834
Reaction score
0

Homework Statement


Hi

I want to find the commutator between the momentum operator p and σz, the third Pauli spin matrix. I am not quite sure how to get started on this one. Can I get a push in the right direction?

For the record, I would say that it is zero since they act on different spaces. Is this correct?


Niles.
 
Physics news on Phys.org
I think it's important to specify a direction for the momentum operator. I think that, if it's x-momentum and z-spin and you measure x-momentum to be zero every time then you know that the spin vector is probably in the x direction telling you for sure that z-spin is zero, meaning they don't commute.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
5K
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K