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# Photon Spin Entanglement

In the Face Book group:
my post:

Tests of photon entanglement use the spin attribute of a photon. Is this truly a test of quantum entanglement?

It is really a test of the light polarization of the electromagnetic fields in the EM radiation we see as light.

I posted about the photon on 03/09; an excerpt:

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A photon is just a concept developed by quantum physicists to describe electromagnetic radiation using the definitions common among subatomic particles

'
Some time before the discovery of quantum mechanics people realized that the connection between light waves and photons must be of a statistical character. What they did not clearly realize, however, was that the wave function gives information about the probability of one photon being in a particular place and not the probable number of photons in that place. The importance of the distinction can be made clear in the following way. Suppose we have a beam of light consisting of a large number of photons split up into two components of equal intensity. On the assumption that the beam is connected with the probable number of photons in it, we should have half the total number going into each component. If the two components are now made to interfere, we should require a photon in one component to be able to interfere with one in the other. Sometimes these two photons would have to annihilate one another and other times they would have to produce four photons. This would contradict the conservation of energy. The new theory, which connects the wave function with probabilities for one photon gets over the difficulty by making each photon go partly into each of the two components. Each photon then interferes only with itself. Interference between two different photons never occurs.
—Paul Dirac, The Principles of Quantum Mechanics, Fourth Edition, Chapter 1
'
more from wikipedia:
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The angular momentum of light is a vector quantity that expresses the amount of dynamical rotation present in the electromagnetic field of the light. While traveling approximately in a straight line, a beam of light can also be rotating (or "spinning", or "twisting") around its own axis. This rotation, while not visible to the naked eye, can be revealed by the interaction of the light beam with matter.

There are two distinct forms of rotation of a light beam, one involving its polarization and the other its wavefront shape. These two forms of rotation are therefore associated with two distinct forms of angular momentum, respectively named light spin angular momentum (SAM) and light orbital angular momentum (OAM).

The total angular momentum of light (or, more generally, of the electromagnetic field and the other force fields) and matter is conserved in time.
Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. An individual photon can be described as having right or left circular polarization, or a superposition of the two. Equivalently, a photon can be described as having horizontal or vertical linear polarization, or a superposition of the two.
'

Therefore:
when the electromagnetic radiation is observed that phenomenon can be described as a photon with its various attributes including mass=0, electric charge=0, parity=-1, and spin.

the photon's spin value is the light's EM angular momentum.
I am surprised there is no frequency or wavelength attribute shown in the wikipedia definition.

From another on-line reference, (at hyperphysics.phy-astr.gsu.edu):
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According to the Planck hypothesis, all electromagnetic radiation is quantized and occurs in finite "bundles" of energy which we call photons. The quantum of energy for a photon is not Planck's constant h itself, but the product of h and the frequency. The quantization implies that a photon of blue light of given frequency or wavelength will always have the same size quantum of energy. For example, a photon of blue light of wavelength 450 nm will always have 2.76 eV of energy. It occurs in quantized chunks of 2.76 eV, and you can't have half a photon of blue light - it always occurs in precisely the same sized energy chunks.

But the frequency available is continuous and has no upper or lower bound, so there is no finite lower limit or upper limit on the possible energy of a photon. On the upper side, there are practical limits because you have limited mechanisms for creating really high energy photons. Low energy photons abound, but when you get below radio frequencies, the photon energies are so tiny compared to room temperature thermal energy that you really never see them as distinct quantized entities - they are swamped in the background. Another way to say it is that in the low frequency limits, things just blend in with the classical treatment of things and a quantum treatment is not necessary.
'
Therefore:
when there is a test for entanglement between photons this test uses the measured electromagnetic radiation at the two points.The test is a comparison of the photon model for one sample with that of the other sample. Any observed entanglement is between those two models; spin is in that model.

There is no physical photon particle to 'possess' the spin attribute.

Immediately after this was posted it was given 'angry' feedback by one person, with no comment.
I responded with this comment:

This post is about only the photon; no other subatomic particles are mentioned.

Another response; this comment was submitted by another person (not the angry one):
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These are some interesting ideas, I dont fully know how to refute them conceptually. But there are some 'proofs' you should consider.
If light hits a sensitive photodetector, the detector registers the energy in a somewhat random series of clicks and not a steady output.
The photoelectric effect can be measured and as light hits a metal surface it is delivered in 'packets' equal to hf, as predicted.
There are other less obvious proofs as well.
'

My response to that comment:

I had the same thought before I posted, whether this conclusion is verifiable.
Photon detectors are tuned for the wavelength so they try to catch one and only one wave. That one wave is then called a photon. They are seeking a photon particle but are detecting one wave.
I could be wrong. I do not own a photon detector. My post referenced what is known about photons so I posted my conclusion. If I came to the wrong conclusion I must be interpreting my references wrong.

That person responded with a like to my comment.

I added another comment to the post:

I interpret a single photon source device as designed to generate one and only one wave of EM at the desired frequency. That would be counted as one photon.

This massless particle holding synchronized electromagnetic fields cannot be created in a device, unless it generates one wave.

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