Wave-packets with opposite momenta.

  • Context: Graduate 
  • Thread starter Thread starter alemsalem
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around the possibility of preparing a particle with wave-packets that have momenta in opposite directions, leading to two localized packets moving away from each other. The scope includes theoretical considerations of wave-packets, tunneling phenomena, and the properties of phase velocity in quantum mechanics.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant questions the feasibility of preparing a particle with wave-packets moving in opposite directions.
  • Another participant suggests that this can be achieved by sending a particle at a potential barrier, leading to tunneling and reflection, resulting in two portions of the wave function moving in opposite directions.
  • Several participants discuss the phase velocity of electrons, with one asking if it exceeds the speed of light and another asserting that it does not, proposing a relationship between phase velocity and group velocity.
  • A participant provides a rough calculation of phase velocity, indicating it is approximately half the particle's velocity.

Areas of Agreement / Disagreement

There is no consensus on the phase velocity of electrons, with differing opinions on whether it exceeds the speed of light. The discussion on wave-packets and tunneling also remains exploratory without a definitive conclusion.

Contextual Notes

Participants express uncertainty regarding the implications of phase velocity and its relationship to the speed of light, as well as the complexities involved in the original question about wave-packets.

alemsalem
Messages
173
Reaction score
5
Is it possible to prepare a particle with a wave-packet having momenta in opposite directions,
so that you have two localized packets moving away from each other (for a single particle)?
 
Physics news on Phys.org
Sure. Send a particle at a potential barrier with a height and width such that the particle has some probability to tunnel through, and some probability to be reflected. After encountering the barrier, a portion of the particle's wave function will be on the other side of the barrier traveling in the original direction, while a different portion will be moving away from the barrier opposite the original direction of motion, having been reflected.
 
is phase velocity of electron in microwave sense is greater than speed of light?
 
please solve my problem...
is phase velocity of electron is greater than speed of light.?
 
i think its very complicated things..
 
its not higher than the speed of light, I think its half the particle's velocity (group velocity)

Vphase = (h*omega)/(h k) = (p^2/2m)/p = p/2m = v/2 roughly speaking..
 

Similar threads

  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 32 ·
2
Replies
32
Views
4K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 70 ·
3
Replies
70
Views
8K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 17 ·
Replies
17
Views
2K
  • · Replies 22 ·
Replies
22
Views
2K
  • · Replies 16 ·
Replies
16
Views
3K