Tunneling with broadening of energy levels

In summary, the problem at hand is calculating the probability of an electron tunneling through a barrier with fixed initial and final energies that have a certain broadening. The solution involves creating a wave packet initially on the left, moving towards the barrier, and then emerging as two packets, one moving to the left and one to the right. This can be analytically shown by summing the results of a planewave.
  • #1
MrPhoenix
1
0
Dear all,
I was wondering about the problem of calculating the probability that an electron will tunnel through a certain barrier (let's assume it is a constant value). Problem is that the initial and final energies of the electron are fixed and possesses a certain broadening (for example gaussian on each of initial and final energies). Does anyone have any suggestion on how to treat such problem?

Any comment is deeply appreciated.
 
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  • #2
This is not enough information. By superposing states in a narrow energy band, you can get states with very different physical properties; for example, you can get a wave packet localized (in position) on the left side of the barrier, and moving to the left. Now tunneling is not an issue because the wave packet never hits the barrier!

The interesting problem is to create a wave packet initially on the left, but moving to the right, towards the barrier. It will hit the barrier, and then two packets will emerge, one on the left moving to the left, and one on the right moving to the right. The probability of the transmitted packet will be given (to a good approximation) by the usual formula from the plane-wave analysis. It's possible to show this analytically by making various approximations (I once worked through it, but I'm sorry I can't supply a specific reference where it's done).
 
Last edited:
  • #3
MrPhoenix said:
Dear all,
I was wondering about the problem of calculating the probability that an electron will tunnel through a certain barrier (let's assume it is a constant value). Problem is that the initial and final energies of the electron are fixed and possesses a certain broadening (for example gaussian on each of initial and final energies). Does anyone have any suggestion on how to treat such problem?

Any comment is deeply appreciated.

What you can do is look at the result for a planewave and then sum them according to your choice of superpositions.
 

Related to Tunneling with broadening of energy levels

1. What is tunneling with broadening of energy levels?

Tunneling with broadening of energy levels refers to the phenomenon in quantum mechanics where a particle can pass through a barrier even if it does not have enough energy to overcome the barrier. This is possible due to the uncertainty principle, which allows for a small probability of the particle being on the other side of the barrier.

2. How does tunneling with broadening of energy levels occur?

Tunneling with broadening of energy levels occurs when a particle with a certain energy level encounters a potential barrier. The barrier causes the energy level of the particle to broaden, or spread out, which increases the probability of the particle tunneling through the barrier.

3. What are some real-life applications of tunneling with broadening of energy levels?

Tunneling with broadening of energy levels has many practical applications, including in the development of transistors and other electronic devices. It is also used in scanning tunneling microscopy, which allows scientists to study the surface of materials at the atomic level.

4. What factors affect the probability of tunneling with broadening of energy levels?

The probability of tunneling with broadening of energy levels is affected by several factors, including the width and height of the barrier, the energy level of the particle, and the mass of the particle. A higher barrier or lower energy level will result in a lower probability of tunneling.

5. What are some limitations of tunneling with broadening of energy levels?

While tunneling with broadening of energy levels has many practical applications, it also has limitations. For example, it is only applicable to particles with very small masses, such as electrons. It also becomes less significant as the barrier width increases, making it less useful for larger scale systems.

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