Double slit experiment with magnetic traps

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Discussion Overview

The discussion revolves around a proposed modification of the double-slit experiment using magnetic traps for single electrons or electron beams. Participants explore the feasibility of maintaining superposition while measuring magnetic induction in the context of the experiment.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether the proposed setup could indeed keep electrons in superposition while measuring magnetic induction, suggesting it may merely detect which slit the electron went through.
  • Another participant emphasizes that the wavefunction collapses only upon measurement, arguing that the goal of maintaining superposition could be achievable if no information about the path is obtained.
  • Concerns are raised about the effects of acceleration on electrons in circular motion, with some participants noting that centripetal acceleration is involved.
  • There is a discussion about the nature of information transfer and its role in wavefunction collapse, with differing views on whether any interaction with the environment could lead to collapse.
  • One participant references the Stern-Gerlach experiment to illustrate how superposition can evolve through magnetic fields without collapsing until a measurement is made.
  • Another participant challenges the idea that it is possible to measure whether the electron went through both traps, asserting that this would imply the existence of two electrons.
  • Participants express uncertainty about the implications of measuring magnetic induction versus current, debating whether indirect measurements could avoid collapse.
  • A link to an external source is provided to discuss a similar experiment involving magnetic fields that purportedly does not cause collapse, prompting further exploration of the topic.

Areas of Agreement / Disagreement

Participants express differing views on whether the proposed experiment can maintain superposition without collapsing the wavefunction. There is no consensus on the implications of measuring magnetic induction or the nature of information transfer in relation to wavefunction collapse.

Contextual Notes

Participants highlight potential limitations in the proposed experiment, including the effects of environmental interactions and the nature of measurements that could lead to wavefunction collapse. The discussion remains open-ended regarding the feasibility of the experiment and the interpretations of quantum mechanics involved.

  • #31
PeroK said:
This is perhaps a good time to pause, reflect and consider learning a bit more about QM, what it says and what it doesn't say.

There is not a lot of point in arguing about things that are well-established, theoretically and experimentally.
Thx for all the answers.
 
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  • #32
PeterDonis said:
The magnetic induction measurement...is a measurement. That's why we use expressions like, oh, say, "measure the magnetic induction" (which is what you said in the OP of this thread) to describe it.
Correct. The difference is that I don't measure the effect or presence of a single electron, but the effect caused by the whole bunch of them. This is my idea of preventing the collapse of individual electrons, however stupid it sounds.
 
  • #33
Marcin said:
I don't measure the effect or presence of a single electron, but the effect caused by the whole bunch of them.

In other words, you run a large number of electrons through the experiment, and then measure the magnetic induction in each of the traps?

Marcin said:
This is my idea of preventing the collapse of individual electrons

It won't.

First, you'll have the problem that magnetic traps can't store large numbers of electrons--the Pauli exclusion principle prevents it (there are only a small number of states the electrons in the trap can be in, and once those states are filled you're done, the trap can't hold any more electrons).

Second, when you do the magnetic induction measurement, you'll just get two numbers for magnetic induction that will be approximately equal (since each electron has basically a 50-50 chance to go into one trap vs. the other). You won't get anything that shows interference between the electrons (which pretty much invalidates the point of doing a double slit experiment in the first place).

Third, even though you have multiple electrons in both traps, you haven't "prevented collapse"; you've just changed the states that the electrons collapse into when you make the magnetic induction measurement, as compared to the case where you only have one electron and it has a 50-50 chance to be in either trap. (The states change because if the presence of multiple electrons in the trap affects the energy levels of the states, due to the Coulomb repulsion between the electrons.)
 
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  • #34
@PeterDonis I get it, you've made it clear. Thank you.
 
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