A question about energy in a harmonic potential

Click For Summary

Discussion Overview

The discussion revolves around determining the probability of measuring a specific energy for a particle in a harmonic potential. Participants explore concepts related to quantum mechanics, particularly the harmonic oscillator model, and the methods to identify the most probable energy measurement.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant asks how to find the probability of measuring a certain energy and which energy is most probable.
  • Another participant suggests that elementary quantum physics textbooks, such as Griffiths, provide answers to the question.
  • A participant explains that the state of the particle can be expressed as a linear combination of the eigenstates of the simple harmonic oscillator (SHO) Hamiltonian, and that the probability of measuring a specific energy is related to the coefficients of this combination.
  • A follow-up question is raised about whether one must calculate probabilities for all possible energies to determine the most probable energy.
  • Another participant confirms that if the most probable energy cannot be identified by inspection, calculations will be necessary.
  • A participant inquires whether the expectation value of energy always corresponds to the largest probability and asks for examples where one can determine the most probable energy by inspection.
  • One participant suggests that the probability density for an operator can be used to find the maximum probability for energy measurements.

Areas of Agreement / Disagreement

The discussion includes multiple viewpoints on how to approach the problem of finding the most probable energy, with no consensus on whether the expectation value always has the largest probability or on the necessity of calculating probabilities for all energies.

Contextual Notes

Participants express uncertainty regarding the conditions under which one can determine the most probable energy by inspection, and the discussion does not resolve whether the expectation value of energy is always the most probable measurement.

Physicist
Messages
43
Reaction score
0
Hi all,

If there is a particle in a harmonic potentail how can we find the probability that a single measurment of the system would yield to a certain energy?

How can we know which is the most probable enegy?

Thanks
 
Physics news on Phys.org
I think you can find a neat answer in all elementary quantum physisics books.
See for example:
Griffiths
 
You need to know the state of the particle as a linear combination of the eigenstates φn of the SHO Hamiltonian:

ψ=Σanφn

The probability of finding the partcle with energy En is the square of the modulus of the corresponding an, and the most probable energy is the eigenvalue for which this probability is largest.
 
Tom Mattson said:
and the most probable energy is the eigenvalue for which this probability is largest.

Should I calculate the probability for all possible energies to know which one has the largest probability??

Thanks
 
Physicist said:
Should I calculate the probability for all possible energies to know which one has the largest probability??

If you can't tell by inspection, then you'll have to.
 
Can I say that the expectation value of the energy always has the largest probability?

&

In which cases can I tell by inspection? Can you give an example please?

Thank you very much..
 
If you want the most probably Energy or whatever just think about it this way. The probability density for some operator X, is just

psi^* X psi.

Find the maximum for this distribution.
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 29 ·
Replies
29
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 67 ·
3
Replies
67
Views
8K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K