Ket bra notation, and radial momentum

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Discussion Overview

The discussion revolves around the interpretation of ket bra notation involving the radial momentum operator and the treatment of a comma in the expression . Participants explore the meaning of this notation in the context of quantum mechanics, particularly regarding wavefunctions and quantum numbers.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant states that = and seeks clarification on the comma in the notation.
  • Another participant expresses confusion about the use of a comma, noting they have never seen it used in that context and questioning the meaning of two wavefunctions in the expression.
  • A different participant suggests it might be a typo in the source material, referencing their experience with commas used for angular momentum quantum numbers.
  • One participant explains that the letters in bra or ket notation represent quantum numbers related to some operator, proposing that "pr,g" refers to two different quantum numbers.
  • Another participant challenges this interpretation, asserting that "pr" should be understood as the radial momentum operator \hat{p}_{r} rather than a quantum number, and questions the existence of quantum numbers for momentum.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the meaning of the notation . There are competing interpretations regarding the role of the comma and the nature of the terms involved.

Contextual Notes

There is uncertainty regarding the correct interpretation of the notation, with some participants suggesting it may be a typo or misrepresentation. The discussion highlights the ambiguity in the use of commas in quantum mechanical notation.

Ed Quanta
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I am told that <f|pr,g>=<prf|g> where pr is the operator for radial momentum and f and g are wavefunctions.

I know how to calculate <prf|g>, but I am not sure how to treat the comma in <f|pr,g>.

Anyone have an answer to this?
 
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Ed Quanta said:
I am told that <f|pr,g>=<prf|g> where pr is the operator for radial momentum and f and g are wavefunctions.

I know how to calculate <prf|g>, but I am not sure how to treat the comma in <f|pr,g>.

Anyone have an answer to this?
Who was it that told you that? I've never see a comma used like that. It has no meaning to me. A wave function is in a one-to-one correspondance with a bra or a ket so I don't see what two wave functions mean in there.

Pete
 
Maybe it is a typo in the book but I am not sure. I have only
seen commas used in kets when distinguishing between m and l values for angular momentum of a particle.
 
the letters inside a bra or ket denote the quantum numbers of that state with respect to some operator.
the notation pr,g must just refer to 2 different quantum numbers
 
Newton said:
the letters inside a bra or ket denote the quantum numbers of that state with respect to some operator.
the notation pr,g must just refer to 2 different quantum numbers

It's not possible...That "pr" is supposed to be [itex]\hat{p}_{r}[/itex] and not a quantum number.And besides,what quantum numbers are there for momentum??

Daniel.
 

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