Modified DIY Quantum Eraser Experiment Does Not Support Which-Path Information Theory

[bangstrom]

I am interested in knowing if anyone can repeat my modification of the "DIY Quantum Eraser Experiment". Directions for how to perform the experiment can be found on YouTube. 

My modification involves replacing the two linearly polarized films in the experiment with two circularly polarized films to see what happens. I have observed that marking the two light paths with circularly polarized light does not erase the interference pattern contrary to the which-path theory.

Ordinary clear cellophane tape "Scotch tape" serves well as a circular polarizing film and the tapes become orthogonal at a 45 degree angle. The tapes can be applied to glass for support. A microscope slide is ideal. The correct polarizing angle can be verified by examining the films sandwiched between two linear polarizing films or better by examining the films through polarized glasses when backlit by light from a flat screen LCD monitor.

Quote from wiki:

“However, in 1982, Scully and Drühl found a loophole around this interpretation.[11] They proposed a "quantum eraser" to obtain which-path information without scattering the particles or otherwise introducing uncontrolled phase factors to them. Rather than attempting to observe which photon was entering each slit (thus disturbing them), they proposed to "mark" them with information that, in principle at least, would allow the photons to be distinguished after passing through the slits. Lest there be any misunderstanding, the interference pattern does disappear when the photons are so marked. However, the interference pattern reappears if the which-path information is further manipulated after the marked photons have passed through the double slits to obscure the which-path markings. Since 1982, multiple experiments have demonstrated the validity of the so-called quantum "eraser"”

I have always been more than a little dubious about the theory that "which-path" information can alter the results of an experiment and the Fresnel-Arago Laws explain the experiment so much better without the quantum woo.

[swansont]

35 minutes ago, bangstrom said:

My modification involves replacing the two linearly polarized films in the experiment with two circularly polarized films to see what happens. I have observed that marking the two light paths with circularly polarized light does not erase the interference pattern contrary to the which-path theory.

How is this identifying which path, and how do are you then obscuring this information? 

[bangstrom]

1 hour ago, swansont said:

How is this identifying which path, and how do are you then obscuring this information? 

I am saying the which-path information is not telling us which way the photon went through the double slit but something else. Most likely it is telling us which slit the transverse light wave went through on the dielectric plane. I am also saying the absence of an interference pattern was explained in classical physics by Fresnel and Aragon and it has nothing to do with our observation of which-path information.

I have not yet explained how the electrical observation of the photon path applies, but similar to observations with polarized light, the Delayed Choice Quantum Eraser can be explained as involving the combined effects of both linear and polarized light emerging from the birefringent crystals. This is no different from the technology used for the modern type of 3D movies.

[Markus Hanke]

11 hours ago, bangstrom said:

the Delayed Choice Quantum Eraser can be explained as involving the combined effects of both linear and polarized light emerging from the birefringent crystals.

But this has nothing to do with optics - you can send any kind of quantum object through the apparatus (with the appropriate components), and get the same behaviour. The outcome isn’t specific to photons/light - the outcome is in fact totally independent of the type of quantum object used.

[bangstrom]

4 hours ago, Markus Hanke said:

But this has nothing to do with optics - you can send any kind of quantum object through the apparatus (with the appropriate components), and get the same behaviour. The outcome isn’t specific to photons/light - the outcome is in fact totally independent of the type of quantum object used.

The delayed choice double slit quantum eraser has EVERYTHING to do with optics. What happens when you send an electron through a BBO crystal or a C-60 molecule through a polarizing filter? It only works with light.

[swansont]

12 hours ago, bangstrom said:

The delayed choice double slit quantum eraser has EVERYTHING to do with optics. What happens when you send an electron through a BBO crystal or a C-60 molecule through a polarizing filter? It only works with light.

Markus is correct; there is nothing about this inherently tied to photons. You would use different equipment if you were investigating e.g. electron spin effects. You can entangle spin states and manipulate them to get the same results as with photons. People use photons because it’s convenient, not because it’s required.

On 10/15/2021 at 7:20 AM, bangstrom said:

I am saying the which-path information is not telling us which way the photon went through the double slit but something else. 

It sounds like you need to establish what this new physics is.

On 10/15/2021 at 4:31 AM, bangstrom said:

My modification involves replacing the two linearly polarized films in the experiment with two circularly polarized films to see what happens. I have observed that marking the two light paths with circularly polarized light does not erase the interference pattern contrary to the which-path theory.

If that’s all you’ve done, then you aren’t doing a which-path measurement, because circularly polarized light doesn’t discriminate between the photons the way linearly polarized light will.

[Markus Hanke]

19 hours ago, bangstrom said:

What happens when you send an electron through a BBO crystal or a C-60 molecule through a polarizing filter?

That is why I mentioned ‘using appropriate components’ in my post.

Anyway, what the experiment establishes is a general property of quantum systems, and nothing inherently to do with photons.