Papers on Splitting single particles

[Quant]

TL;DR Summary

Experiments of 2023 show splitting of particles

Dear group members,

Can you express your opinion on the following recent (2023) articles insisting that single particles are split in parts in double slit and in Mach -Zehnder interferometer.Is this splitting compatible with QM/QFT? Parts of the abstracts are included here. The full articles are free accessible on Google Science.

A possible solution to the which-way problem of quantum interference Holger F. Hofmann

"Experimentally observable effects of small polarization rotations applied in the slits of a double slit experiment indicate that individual particles passing the slits before their detection in the interference pattern are physically delocalized with regard to their interactions with the local polarization rotations."

"Particles detected in the interference maxima experience no fluctuations at all, indicating a presence of exactly one half of the particle in each slit, while particles detected close to the minima experience polarization rotations much larger than the local rotations, indicating a negative presence in one of the slits and a presence of more than one in the other."


Quantifying the presence of a neutron in the paths of an interferometer Lemmel et.al.

"The results show that individual particles experience a specific fraction of the magnetic field applied in one of the paths, indicating that a fraction or even a multiple of the particle was present in the path before the interference of the two paths was registered."

 

[PeterDonis]

@Quant, please give specific links when you reference papers; just saying "Google Science" is not enough. Here are the preprints I found on arxiv.org:

A possible solution to the which-way problem of quantum interference Holger F. Hofmann

https://arxiv.org/abs/2111.03203v2

Quantifying the presence of a neutron in the paths of an interferometer Lemmel et.al.

https://arxiv.org/abs/2202.00272

 

[PeterDonis]

Is this splitting compatible with QM/QFT?

Are you asking whether the observed experimental results are "compatible with QM/QFT"? If so, the answer is yes, of course they are. Nor do the papers say otherwise.

If you are asking about the particular ordinary language description the papers use, such as phrases like "the particles forming the interference pattern must have been physically delocalized" or "an individual neutron moving through a two-path interferometer may actually be physically distributed between the two paths", those descriptions are interpretation dependent, so discussion of that would belong in the interpretations subforum (and there would be no way to actually resolve the question you are asking because interpretations are not experimentally testable, they all make the same predictions).

 

[Quant]

In QM/QFT a particle is pointlike (almost) not physically distributed.
Distributed is only the wavefunction and it has interpretations.
The fact that neutron is distributed in these experiments is experimental but results are received through weak measurements (introduced by Lev Vaidman) not usual strong ones.
My opinion is that neither QM no QFT predict something similar.
So this is a very initial incident where they fell and must be adjusted somehow as it happened with classical Electrodynamics after Planck black body formula or Newton mechanics after GTR.
The author don't claim this explicitly because of prudence. But clearly say the neutron were entered one at a time and this is not an average result by no means.

I hope other members will join the conversation.

 

[weirdoguy]

I hope other members will join the conversation.

My take is that you showed repeatedly that you don't have enough knowledge to have any opinion on that, and other matters of QM or QFT.

My opinion is that neither QM no QFT predict something similar.

Nonsense.

The author don't claim this explicitly because of prudence.

Nonsense.

Summary: you are here not to learn, but to present some conspiracies and pseudoscience. What for? Like if real world and life wasn't tough enough.

 

[DrChinese]

I hope other members will join the conversation.

After looking at the links provided by @PeterDonis, I guess I don't fully understand what you are trying to say. I don't read anything as an unexpected prediction of QM, nor as an unexpected experimental result. As indicated by references, there has been plenty of discussion in recent (and far past!) years about trying to nail down the path of quantum particles between times T1 and T2 when no direct observations occur. Generally speaking, there is no single (spacetime) path which can be assigned in all contexts.

So to me, when Hofmann refers to "delocalization", that seems normal - not new. And when you talk about a particle being physically split, that seems like description not justified from these papers. I certainly don't believe there is such a thing as two "half-electrons". But it would NOT be surprising (to me) to say a full electron is 50% here and the same full electron is 50% there - when we are not looking.

A lot of it goes back to interpretations (as mentioned by Peter), as different ones might describe these situations with different words.

 

[Nugatory]

In QM/QFT a particle is pointlike (almost) not physically distributed.

It would be more accurate to say that particle detections are (almost) pointlike.

That is the only experimentally confirmed and interpretation-free fact that we have here. We can’t get from facts about particle detections to facts about particles without introducing usually unstated always unjustifiable additional assumptions about the behavior of unobserved particles.

 

[iste]

In QM/QFT a particle is pointlike (almost) not physically distributed.
Distributed is only the wavefunction and it has interpretations.
The fact that neutron is distributed in these experiments is experimental but results are received through weak measurements (introduced by Lev Vaidman) not usual strong ones.
My opinion is that neither QM no QFT predict something similar.
So this is a very initial incident where they fell and must be adjusted somehow as it happened with classical Electrodynamics after Planck black body formula or Newton mechanics after GTR.
The author don't claim this explicitly because of prudence. But clearly say the neutron were entered one at a time and this is not an average result by no means.

I hope other members will join the conversation.

I saw the author talk about this experiment on youtube and iirc they said it was just what they were expecting from quantum theory, nor do they strongly assume a specific interpretation I think. They must be just equating "particle" and quantum state / wavefunction in a super general way.



Also, re: what weak measurements and values show -

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.023048

 

[PeterDonis]

it was just what they were expecting from quantum theory

In terms of the results being consistent with what QM predicts, yes.

nor do they strongly assume a specific interpretation

They don't explicitly do so, but as I noted in post #3, some of the descriptions given in the papers do implicitly assume a particular kind of interpretation.

 

[Quant]

After looking at the links provided by @PeterDonis, I guess I don't fully understand what you are trying to say. I don't read anything as an unexpected prediction of QM, nor as an unexpected experimental result. As indicated by references, there has been plenty of discussion in recent (and far past!) years about trying to nail down the path of quantum particles between times T1 and T2 when no direct observations occur. Generally speaking, there is no single (spacetime) path which can be assigned in all contexts.

So to me, when Hofmann refers to "delocalization", that seems normal - not new. And when you talk about a particle being physically split, that seems like description not justified from these papers. I certainly don't believe there is such a thing as two "half-electrons". But it would NOT be surprising (to me) to say a full electron is 50% here and the same full electron is 50% there - when we are not looking.

That's the point in my argument. Broglie interpretation says neutron 100 % in one point/channel, Copenhagen -full electron 50% here and full electron 50% there, whenever these experiments point 1/2 neutron here and 2/3 there. Is this not totally different?

After looking at the links provided by @PeterDonis, I guess I don't fully understand what you are trying to say. I don't read anything as an unexpected prediction of QM, nor as an unexpected experimental result. As indicated by references, there has been plenty of discussion in recent (and far past!) years about trying to nail down the path of quantum particles between times T1 and T2 when no direct observations occur. Generally speaking, there is no single (spacetime) path which can be assigned in all contexts.

So to me, when Hofmann refers to "delocalization", that seems normal - not new. And when you talk about a particle being physically split, that seems like description not justified from these papers. I certainly don't believe there is such a thing as two "half-electrons". But it would NOT be surprising (to me) to say a full electron is 50% here and the same full electron is 50% there - when we are not looking.

That's the point in my argument. Bohr interpretation is neutron is full and 50% in one channel 50% in other. De Broglie - neutron is full 100% in one channel, an empty wave travelling the other channel. Whereas the experiments show 1/3 in one channel and 2/3 in the other. Is this not totally different?

 

[PeterDonis]

Moderator's note: Thread moved to the interpretations subforum.