Measuring momentum in a square well

In summary, the conversation revolves around the concept of measuring momentum in an infinite or finite square well in quantum mechanics. One of the postulates states that measuring an observable will leave it as an eigenstate of the corresponding operator. However, this presents a problem for both infinite and finite square wells as the wavefunction would exist beyond the boundaries in the former and result in a free particle in the latter. The conversation concludes with a reference to a paper discussing the momentum operator for the square well.
  • #1
thoughtgaze
74
0
Hi

I'm a little confused when it comes to measuring the momentum in a infinite or finite square well. Is this even possible? One of the postulates of quantum mechanics states that measuring an observable will leave it as an eigenstate of that observables corresponding operator just after measurement. Fine and dandy but for an infinite square well this would result in the wavefunction existing beyond the boundaries. For a finite square well this would also result in the wavefunction being an eigenstate of the momentum operator and therefore a free particle. Can someone explain where I am going wrong/what I'm missing. Thanks.
 
Physics news on Phys.org
  • #3
George Jones said:
I think this is a bit subtle. What is the momentum operator for the square well? See

http://arxiv.org/abs/quant-ph/0103153.

This looks great George, thanks. Reading it now.
 

FAQ: Measuring momentum in a square well

1. How is momentum measured in a square well?

Momentum in a square well is measured by taking the product of an object's mass and velocity. This can be calculated using the equation p = mv, where p is momentum, m is mass, and v is velocity.

2. What is a square well potential?

A square well potential is a type of potential energy function that has a flat region surrounded by infinite potential walls. It is commonly used in physics to model the behavior of particles in a confined space.

3. Why is momentum important in a square well?

Momentum is important in a square well because it helps to determine the behavior and motion of particles within the well. It is also used to calculate other important quantities such as kinetic energy and potential energy.

4. How does the depth of the well affect momentum?

The depth of the well can affect momentum by changing the allowed energy levels for particles within the well. A deeper well will have a greater impact on the momentum of particles, as they will have more energy and therefore a higher velocity.

5. Can momentum be conserved in a square well?

Yes, momentum is conserved in a square well, just as it is conserved in any other physical system. This means that the total momentum of all particles within the well will remain constant, even as they interact and change direction.

Similar threads

I Measurements and uncertainty principle
Replies
12
Views
1K
I Momentum eigenfunctions in an infinite well
Replies
31
Views
2K
I On Wave Function Collapse and Accuracy of Energy Measurment
Replies
18
Views
2K
Finding the probability of making a measurement E1
Replies
17
Views
2K
I Question about Uncertainty Principle
Replies
9
Views
2K
I Two Ways of Calculating the Solution to the Infinite Square Well?
Replies
28
Views
2K
I (Baby QM) Analytic Solution to the Infinite Square Well Problem
Replies
2
Views
917
I Physical interpretation of phase in solutions to Schrodinger's Eqn?
Replies
12
Views
3K
I Is there a reason eigenvalues of operators correspond to measurements?
Replies
2
Views
1K
Eigenfunction of multiple operators simultaneously?
Replies
4
Views
2K

Hot Threads

Recent Insights

Back
Top