Questioning Quantum Rules: Is A(A or B) = A(A) + A(B)?

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Homework Help Overview

The discussion revolves around the interpretation of quantum probability rules, specifically questioning the relationship between amplitudes and probabilities in the context of events A and B. The original poster expresses confusion about the correct formulation of the quantum rule regarding the addition of amplitudes and their squared values.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to clarify the quantum rule for calculating probabilities from amplitudes, questioning whether the sum of squared amplitudes should equal one or if it should be the square of the sum of amplitudes. Other participants engage with this confusion, suggesting different interpretations and considerations regarding interference terms.

Discussion Status

Participants are actively exploring the nuances of quantum probability rules, with some providing insights into the relationship between amplitudes and probabilities. There is a lack of explicit consensus, but the discussion is generating productive questions and considerations about the underlying principles.

Contextual Notes

Participants reference specific quantum mechanics concepts and terms, such as amplitudes and interference, indicating a shared understanding of the subject matter. There are also indications of additional questions related to other parts of the homework, suggesting ongoing engagement with the material.

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Homework Statement



See q attached

Homework Equations





The Attempt at a Solution



So basically... my questions is this:

I thought that the rule in quantum for p(A or B) is that A(A or B) = A(A) + A(B) then you square [A(A) + A(B)] to find p(A or B) (where A(X) is amplitude of X)

But then surely the sum of the amplitudes all squared must = 1 rather than sum of amplitudes squared added..
i.e. in this example surely it would be that |(a+b)^2| = 1 rather than |a^2| + |b^2| =1 ?
but i think the latter is the right method...

please help!
 

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Physics news on Phys.org
anyone?
 
hellooo?
 
lal2+lbl2=1

where lal2 is aa*
 
so why is the 'quantum rule' that you add amplidues for different ways of an event happening..i.e.
A(A or B) = A(A) + A(B) then you square [A(A) + A(B)] to find p(A or B)

so p(A or B) = p(A) + p(B) + I (interference term)
..
 
That is if you have two particles.
 
aha okay thanks
 
No 0 e^PIi squared is 1 so a=0
 
Bendavid2 said:
No 0 e^PIi squared is 1 so a=0

sorry - posted the wrong q - meant this one...part b
 

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  • #10
3/4?
 
  • #11
Yup I think so. Chance of finding it in well 0 is 1/2 due symmetrie both side are even so 1/4 + 1/2 is 3/4 so yup.
 
  • #12
noice thinking..you = quantum god.
 
  • #13
Bendavid2 said:
Yup I think so. Chance of finding it in well 0 is 1/2 due symmetrie both side are even so 1/4 + 1/2 is 3/4 so yup.

sorry to be a pain. thanks for you help.. also stuck on q11 c
 

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