Particle goes through a double slit + decays, what happens?

[Paper]

What would happen if you send a particle towards a double slit, it goes through interacting with itself quantumly, however before it reaches the screen it decays emitting radiation (Alpha, beta and/or Gamma)?

Would you still see the same pattern on the screen?
Would it affect the wave function of the original particle? What if it were only gamma radiation?
Would it affect the particle's trajectory?

The reason I am curious to know is because I am wondering if you could use the decay to attempt to spy on the particle's path. The main accepted theory for describing the double slit experiment is the "Copenhagen interpretation", however there are alternatives like "De Broglie–Bohm". If it were somehow possible to spy on the particles without touching them (i.e disturbance through measurements), then one could determine if the main theory stands true or if another theory is a better match.

At any rate, my understanding of physics isn't too great.

 

[mfb]

That will depend on details of the setup. The non-decayed particle can interfere with itself, but the decay is usually an incoherent process (decays at different places don't interfere with each other). If you track the decay products and reconstruct the decay point you might get some sort of 2D interference pattern (not just at the distance of the screen, but also before that).

 

[PaleMoon]

when you have possible decay, the "fringe visibility" decreases.

 

[Paper]

So just to make sure I understood these replies in plain English:

* mfb: Your saying that if a particle decays you may be able to track the original particle's position by examining the end position and momentum of the decay products. However that the decay products won't be in "magical quantum interference mode".

* PaleMoon: You are saying that when a particle decays, all products of the decay are no longer interfering with themselves, that the interference of the original particle is lost/not occurring still (because the original particle is now two bits) and therefore that the interference pattern on the screen decreases?


In my mind, the set up would be the particle gun, the two slits near by that gun and then a long distance to the screen, with the distance creating a high probability of seeing decay after the slits but before the particle gets to the screen. Doing this, you could track the decay products all around the experiment area in order to try to track where the product was at the time of decay. If you created a map of all these decay source points then:
* If the quantum superposition theory is true, you can expect the decay products source points to be a random collection
* If pilot wave theory is true, you might expect the decay products source point collections to fit into a predictable pattern

Interestingly someone found a way to determine which slit the particle goes through without messing up the interference pattern: https://arstechnica.com/science/201...rticle-duality-in-the-double-slit-experiment/

How pilot wave theory could even begin to explain Delayed Choice Quantum Eraser is beyond me.

 

[mfb]

* If the quantum superposition theory is true, you can expect the decay products source points to be a random collection
* If pilot wave theory is true, you might expect the decay products source point collections to fit into a predictable pattern

Both are just two different interpretations, they always lead to the same predictions.

Interestingly someone found a way to determine which slit the particle goes through without messing up the interference pattern: https://arstechnica.com/science/201...rticle-duality-in-the-double-slit-experiment/

Well, sort of...

 

[Deepblu]

Interestingly someone found a way to determine which slit the particle goes through without messing up the interference pattern: https://arstechnica.com/science/201...rticle-duality-in-the-double-slit-experiment/

Interesting experiment, what they did actually is using a clever trick of using TEM01 mode combined with entanglement to determine the which path info without disturbing the interference pattern. if this experiment is verified (ex: repeated by others), then the obvious conclusion from it is that which-path info has nothing to do with interference pattern, and that it is actually the measurement we do to know the which-path info is the reason of why the interference pattern disappears. Also it seems that this experiment is in favor of Bohmian Mechanics over the wave collapse interpretation.

Here is a link to the actual paper:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386133/
http://www.pnas.org/content/109/24/9314

Why this experiment is not popular?!

 

[Paper]

@mfb: Well with the current experimental evidence we have both interpretations predict the same results. But if we could do more testing we might be able to find discrepancies ;)

@Deepblu: I thought that too, about the experiment giving favour to Bohmian Mechanics, however how can it explain the Delayed Choice Quantum Eraser experimental results? In fairness how can the wave collapse interpretation even explain that?!

 

[PeterDonis]

I thought that too, about the experiment giving favour to Bohmian Mechanics, however how can it explain the Delayed Choice Quantum Eraser experimental results? In fairness how can the wave collapse interpretation even explain that?!

All QM interpretations use the same underlying math, so they all make the same predictions for all experimental results. The stories they tell in ordinary language are different, but which story you prefer is a matter of opinion, not physics.

 

[Nugatory]

how can it explain the Delayed Choice Quantum Eraser experimental results? In fairness how can the wave collapse interpretation even explain that?!

Try this paper: https://arxiv.org/abs/1707.07884

 

[Demystifier]

What would happen if you send a particle towards a double slit, it goes through interacting with itself quantumly, however before it reaches the screen it decays emitting radiation (Alpha, beta and/or Gamma)?

Would you still see the same pattern on the screen?

No.

Would it affect the wave function of the original particle?

Yes.

What if it were only gamma radiation?

Even then. Gamma radiation takes away energy, and wave function depends on energy.

Would it affect the particle's trajectory?

Yes (whatever you mean by "trajectory").

The reason I am curious to know is because I am wondering if you could use the decay to attempt to spy on the particle's path.

That will not work.

 

[Demystifier]

How pilot wave theory could even begin to explain Delayed Choice Quantum Eraser is beyond me.

Try https://arxiv.org/abs/1703.08341 Sec. 5.1.

 

[Demystifier]

I thought that too, about the experiment giving favour to Bohmian Mechanics, however how can it explain the Delayed Choice Quantum Eraser experimental results? In fairness how can the wave collapse interpretation even explain that?!

Why do you think that Bohmian mechanics or collapse can not explain the delayed choice?