Notation regarding the dipole approximation

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SUMMARY

The dipole approximation in quantum mechanics (QM) is represented by the Hamiltonian \(\hat {V}_{\text{dipole}} = -\mathbf{d}\cdot \mathbf{E}\), where \(\mathbf{E}\) is the electric field and \(\mathbf{d}\) is the dipole operator. Including the hat on the dipole operator, as in \(\hat{\mathbf{d}}\), is not standard practice because it may confuse readers into interpreting it as a unit vector. While it is important for beginners to recognize operators, experienced students can often infer context without the hat. Thus, omitting it is acceptable in advanced discussions.

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  • Understanding of quantum mechanics principles
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  • Basic comprehension of vector notation in physics
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Niles
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Homework Statement


Hi

Whenever I read about the dipole approximation in QM, then the Hamiltonian is given as
<br /> \hat {V}_{\text{dipole}} = -\mathbf{d}\cdot \mathbf{E}<br />
where E is the electric field and d the dipole operator. What I am wondering about is that d is an operator. Is it wrong to include the hat in the interaction? As in
<br /> \hat {V}_{\text{dipole}} = -\hat{\mathbf{d}}\cdot \mathbf{E}<br />This is probably a silly question, but it is something that has been on my mind for some time.Niles.
 
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It's normal to be pedantic about putting hats on operators when students are just starting to learn about them. Later on in the course they can distinguish operators from context, so they might get left off by laziness. In the case of the dipole operator above, it's also likely that putting the hat might cause some readers to believe that it refers to a unit vector, so it's reasonable to leave it off.
 
I see, thanks!
 

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