Native language: EnglishLevel of quantum mechanics: Introductory or beginner

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    Wavefunction Wavepacket
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Discussion Overview

The discussion revolves around the concepts of wavepackets and wavefunctions in quantum mechanics, specifically addressing their differences and applications, such as in the context of a particle in a box. Participants seek clarification on these foundational topics in introductory quantum mechanics.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant defines a wavepacket as a localized wavefunction, suggesting it has high probability amplitude in a small region and low elsewhere, while a wavefunction is described as a solution to the Schrödinger equation.
  • Another participant questions whether the original poster understands the distinction made between wavepackets and wavefunctions.
  • A participant expresses confusion regarding the wavepacket and its relation to the particle in a box, indicating a desire for further clarification.
  • There is an assertion that the terms wavepacket and wavefunction may be used interchangeably, provided the correct mathematical formulation is applied.
  • One participant acknowledges understanding but seeks confirmation on their interpretation of wavepackets and wavefunctions, indicating a potential misunderstanding of the previous explanation.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the concepts discussed, with some agreeing on the definitions while others remain uncertain or confused about the implications and applications of wavepackets and wavefunctions.

Contextual Notes

There are unresolved aspects regarding the definitions and applications of wavepackets and wavefunctions, particularly in relation to energy localization and the context of a particle in a box. The discussion reflects differing interpretations and levels of comprehension among participants.

Alice Jin
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Dear,

I have a trouble understanding QM.
What's the difference between wavepacket and wavefunction?
Can we use a wavepacket for a particle in a box?
Please reply to this questions.
Thank you in advance.
 
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a wavepacket is a wavefunction which is localized, meaning really high in some small region and small everywhere else. a wavefunction is just slang for a solution to the shrodinger eqn.

here's a wavepacket

Coder_Source_Gaussian_Blur_Smoothing_gauss1.gif


see how it's really high around x=0 and hence it's square, which is the probability amplitude, in a very small range and zero everywhere else. hence the particle which this wave packet describes is most likely to have energy around x=0. therefore the energy is in some sense localized.

here's another wave function

http://www.libraryofmath.com/pages/graphs-of-sine-and-cosine/Images/graphs-of-sine-and-cosine_gr_46.gif

the range of values where it's high, and hence it's probability amplitude is high, is just plain weird. hence you couldn't say it's energy is localized.

really there's no difference between the two, it's slang. so if you want you can call the solution to the shrodinger eqn for a particle in a box a wavepacket, bob, or whatever you want- as long as you write down the correct mathematical formula.
 

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Alice Jin said:
Dear,

I have a trouble understanding QM.
What's the difference between wavepacket and wavefunction?
Can we use a wavepacket for a particle in a box?
Please reply to this questions.
Thank you in advance.

uhh... didn't you just ask this same question here:

https://www.physicsforums.com/showthread.php?t=265538
 
Yeah, I did. But I'm not quiet sure about the wavepacket. That's why I asked different subject. Also I think it's different thing.
 
well do you understand my answer?
 
Thanks, ice109.

What you're saying is that the wavepacket has more or less localized energy at the average position even though the wavepacket is composed of lots of different momenta and for the wavefuction I can consider it like the excited state of paticle in a box. Right?
Am I understood?
 
Alice Jin said:
Thanks, ice109.

What you're saying is that the wavepacket has more or less localized energy at the average position even though the wavepacket is composed of lots of different momenta and for the wavefuction I can consider it like the excited state of paticle in a box. Right?
Am I understood?

you are understood but you've misunderstood me. so first tell me what is your native language and what level of quantum mechanics are you studying?
 

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