Question about the spatial extent of a single photon in entanglement

[Aloiz Burher]

TL;DR

Can we interpret entanglement as a single, spatially extended energy body rather than two distinct particles?

Hi everyone,
I’ve been reflecting on the double-slit experiment and entanglement, and I have a question regarding the physical nature of the photon.
Instead of viewing entanglement as two distinct particles that communicate, is it mathematically or physically viable to treat the "entangled system" as a single, spatially extended excitation (an energy body) that has been stretched or deformed?
If we consider the photon as a non-divisible, extended structure (like a "V-shape" in space), wouldn't that resolve the paradox of superluminal signaling? In this model, acting on one "end" of the extended excitation would instantly affect the whole system simply because it's one unified object, not because a signal traveled between two points.
Furthermore, could "wavefunction collapse" be interpreted simply as a mechanical interaction where the detector hits this fragile, extended structure, forcing it to localize back into a point?
I'm curious to hear the mainstream perspective on why we don't treat the entangled photon as a single, physically "long" object instead of two "spooky" twins.


I’d like to offer an even more convenient analogy to clarify my point.

Imagine a U-shaped iron rod buried underground, with only its two ends sticking out of the surface.

• The Illusion of Duality: To an observer who doesn't see the buried part, these look like two separate, independent objects (like a pair of entangled photons).
• Instantaneous Reaction: If you push or pull one end, the other end moves at the exact same moment.
• Unity of State: The second end doesn't move because it received a signal through space. It moves because it is part of the same physical entity.

In my view, 'quantum entanglement' might simply be our observation of an object whose true, extended structure remains hidden from us. In this model, the concept of 'signaling' disappears entirely — the sender and the recipient are the same whole. When one 'end' is affected, the status of the entire object is redefined instantly.

Thanks!

 

[PeterDonis]

I’ve been reflecting on the double-slit experiment and entanglement

There is no entanglement in the double-slit experiment, at least not in the most common version that's discussed, in which you can run the light source at low enough intensity that only a single photon is inside the apparatus at one time, and still have an interference pattern build up over time on the detector screen. The state of photons going through the experiment in that case is not an entangled state. The interference pattern comes from each individual photon interfering with itself, not from any entanglement.

First of all, @Aloiz Burher, welcome to PF!

If we consider the photon as a non-divisible, extended structure (like a "V-shape" in space), wouldn't that resolve the paradox of superluminal signaling?

I'm not sure what "paradox" you're referring to. Superluminal signaling is not possible. There is a theorem in QM called the "no signaling theorem" that establishes that.

In this model, acting on one "end" of the extended excitation would instantly affect the whole system

But it doesn't; this isn't possible.

Furthermore, could "wavefunction collapse" be interpreted simply as a mechanical interaction where the detector hits this fragile, extended structure, forcing it to localize back into a point?

I'm not sure what you mean by this. Please be aware that personal speculation is off limits for discussion here at PF.

 

[Nugatory]

Instead of viewing entanglement as two distinct particles that communicate, is it mathematically or physically viable to treat the "entangled system" as a single....

Of course, and that's always been how we view it: the entangled pair is not two distinct particles, it is a single quantum system described by a single wave function. This is baked into the math of quantum mechanics, and one of the things that surprised classically trained physicists in the early days was that the math didn't allow them to think of the entangled pair any other way. But...

... spatially extended excitation (an energy body) that has been stretched or deformed?

doesn't tell us anything. The physics is in the math, and natural language is useful only to the extent that it helps us understand what the math is telling us.

There really is no way of understanding QM without some understanding of the math behind it. That means a lot of math if you're serious about it, but for a more layman-friendly introduction you could do worse than Giancarlo Ghirardi's book "Sneaking a look at God's cards".

 

[Nugatory]

I’d like to offer an even more convenient analogy to clarify my point.
Imagine a U-shaped iron rod buried underground, with only its two ends sticking out of the surface.

• The Illusion of Duality: To an observer who doesn't see the buried part, these look like two separate, independent objects (like a pair of entangled photons).

This works as an analogy, sort of. QM does indeed say that we have one quantum system here. It just so happens that our measuring devices are in different physical locations. But...

• Instantaneous Reaction: If you push or pull one end, the other end moves at the exact same moment.

does not work at all. When we push or pull one end of a rod, the other end does not move at the exact same moment. Instead the change propagates at some speed less than the speed of light (generally, the speed of sound in whatever material we're working with); but what has to be explained is the apparent faster than light propagation of entanglement effects.

 

[Aloiz Burher]

Adding to my previous thoughts:

Hi everyone! I keep thinking about quantum entanglement and want to better understand its nature.

When considering an entangled pair of photons, is it correct from the perspective of quantum mechanics to think of them not as two separate objects exchanging signals, but as a single quantum system? If so, the lack of delay would be a consequence of it being a single state.

I am also interested in the following question: is it possible to assume that at the quantum level, objects (due to their scale or nature) are unstable or "insufficiently defined" on their own while in a superposition? And only when interacting with our macroscopic level (during measurement) do they "gain significance" and stabilize?

I would be grateful if you could share how this phenomenon is described within the framework of quantum decoherence theory or the measurement problem, thank you for your attention!.

 

[PeterDonis]

@Aloiz Burher I just used magic moderator powers to edit your post #5 to remove the long quote of the OP of this thread--not necessary, there's no need to quote yourself unless you're responding to something specific, and certainly no need to quote the entire OP of this thread again--and to remove the quotes around the actual new content of your post.

 

[PeterDonis]

When considering an entangled pair of photons, is it correct from the perspective of quantum mechanics to think of them not as two separate objects exchanging signals, but as a single quantum system?

Yes, that's now they would normally be modeled in QM, as a single two-photon system in an entangled state.

the lack of delay

What lack of delay?

Several people have already responded in this thread to tell you that your intuition about "delay" in such cases is wrong.

 

[PeterDonis]

is it possible to assume that at the quantum level, objects (due to their scale or nature) are unstable or "insufficiently defined" on their own while in a superposition?

What does this mean? Can you give a specific example of a "superposition" that this question would apply to?

Note that "superposition" does not mean the same thing as "entanglement".

 

[bhobba]

Hi everyone! I keep thinking about quantum entanglement and want to better understand its nature.

What we deal with in ordinary non-relativistic QM is a very good approximation to the non-relativistic limit of Quantum Field Theory (QFT), which is the best theory we currently have. Without going into details (it has to do with ordinary QM does not imply that anti-particles must exist and needs that to be included - but is not), that it is an approximation is of no importance (usually only when considering fundamental issues such as is the wave function a complete description - strictly speaking, it is not - is one part of two wave functions - one for the particle and the other for the antiparticle).

What seems strange in QM is often trivial if you look at it as excitations in a quantum field. An entangled pair is simply the excitation of the field for a pair of particles, taken as a whole. That excitation can be such that it is not the same as the excitation of a single particle and the excitation of another single particle. Such are then called entangled.

Thanks
Bill