Is free electron's motion quantized?

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Discussion Overview

The discussion centers on whether the motion of a free electron is quantized, particularly in the context of manipulating its speed using magnetic fields. Participants explore the implications of quantization and the conditions under which it occurs, as well as the mechanisms by which an electron can change energy levels or orbitals.

Discussion Character

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

Main Points Raised

  • One participant questions if the motion of a free electron is quantized and seeks clarification on the conditions that lead to quantization.
  • Another participant suggests that quantization arises from boundary conditions of the wave function, particularly in the presence of magnetic fields, leading to quantized angular momentum.
  • A later reply expands on the initial question, asking if an electron in a quantized orbit can decrease its energy level without emitting a photon, and whether magnetic fields can facilitate this process continuously.
  • Further contributions mention that in quantum electrodynamics (QED), it is possible to adiabatically change the strength of a magnetic field, allowing energy eigenvalues to change continuously without photon emission, provided the changes are made slowly enough to maintain equilibrium.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms of energy level changes for electrons, particularly regarding the necessity of photon emission. There is no consensus on whether the motion of a free electron is quantized or the conditions under which it may or may not be.

Contextual Notes

Participants reference concepts from quantum mechanics and quantum electrodynamics, indicating that the discussion involves complex theoretical frameworks that may not be fully resolved. The implications of boundary conditions and adiabatic processes are noted as significant factors in the discussion.

sneez
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is free electron's motion quantized?

For example if i knock off electron from an atom and than trap it inside some space where i can manipulate magnetic fields, can i slow and speed up the electron continuously, or will the electron speed be quantized?

please, explain why is it quantized?
 
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Any quantization arises from the boundary conditions of the wave function. Of course, in the case of the magnetic field (in a semi-classical picture), you'll find some sort of quantization of the rotation around the magnetic fields because the particles rotate around them and the angular momentum is quantized.

Quantization is a consequence of various kinds of boundary conditions, usually.
 
That makes sense, thank u
 
I would like to extend the question.

Can electron moving in quantized circular obit 'slow down' or decrees in energy level other way than by emitting a photon?

For example is there i way to slow down an electron by the magnetic fields 'continuously' until it will make 'jump' to lower orbit without emitting a photon?

in general: is the only way to change orbitals to emit photons? or is there another way without emitting the photon?
 
I would like to extend the question.

Can electron moving in quantized circular obit 'slow down' or decrees in energy level other way than by emitting a photon?

For example is there i way to slow down an electron by the magnetic fields 'continuously' until it will make 'jump' to lower orbit without emitting a photon?

in general: is the only way to change orbitals to emit photons? or is there another way without emitting the photon?

The most accurate forum for the discussion of interaction of particles and fields is QED, however QED is very ambigous when it comes to bound state problems. You can adiabatically change the strength of a magnetic field within a first quantised theory and the energy eigenvalues will change continuosly. If it done adiabatically as zero temperature then the particle will remain in the ground state, its energy changing continuously. There is a thery by Gell-mann and Lowe with regard to this.


In QED, External field need not be quantised and as such I would say that yes, this would be possible. The particle will remain in the ground state without the emission of a photon if the potential is altered adiabatically (very slowly such that the system reamins in equilibrium).
 

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