I Quantum Interpretations of this optical effect

[andresB]

I generally stay away from discussion about the interpretations of QM, but just for this time I would like to know what's the point of view from Bohmian, many worlds, thermal and other interpretations of the following: https://arxiv.org/abs/1305.0168

 

[A. Neumaier]

I generally stay away from discussion about the interpretations of QM, but just for this time I would like to know what's the point of view from Bohmian, many worlds, thermal and other interpretations of the following: https://arxiv.org/abs/1305.0168

In the thermal interpretation, the separation into many photons is an illusion, as the real player is the field intensity. Thus the classical analysis given in the paper applies essentially unchanged. The apparent weirdness comes from the erroneous picture that individual photons travel along the beam.

 

[julcab12]

I generally stay away from discussion about the interpretations of QM, but just for this time I would like to know what's the point of view from Bohmian, many worlds, thermal and other interpretations of the following: https://arxiv.org/abs/1305.0168

Illusions are part reality of dynamics. It the same way how Strong lensing, form of gravitational lensing produces fixations of multiplicity-- Illusion(incomplete picture) created by bending of light. Some of the pure relativist argues that a phenomenon on the same value exist in QM. Flat, Straight are a placeholder doesn't exist in nature. Spacetime and fields are intrinsically curved and dynamic. They tend to picture QM in a different light-- Relational without time.

http://philsci-archive.pitt.edu/14179/1/relationalQM.pdf
"According to Rovelli RQM, in the world, there are observers. These are not necessarily human observers, but any physical object, such as a measuring apparatus, would qualify . During a measurement interaction with another object, an observer witnesses an event (a discrete, occurrent entity) corresponding to this object having a determinate property relative to the observer (these properties are not necessarily finely grained physical quantities: it can be a macroscopic aggregated quantity, or, for example, position with a finite degree of precision). Quantum mechanics is what allows an observer (supposedly 1 “In RQM, physical reality is taken to be formed by the individual quantum events (facts) through which interacting systems affect one another. [. . . ] each quantum event is only relative to the system involved in the interaction.”

 

[Heikki Tuuri]

I wonder if there is a calculation error in the paper. EDIT: No error!

We may use particles with a rest mass m in the experiment. We can implement a beam splitter with a wall with a hole in it.

Let us increase the mass m enough, so that the system behaves like a classical system. Then we may assume that the particle did take a definite path through the system. If it ends up at D_2, it definitely did not kick the double-sided mirror M to the left, contrary to what the paper claims. It either did not kick at all, or kicked to the right.

The paper talks about a photon "taking a path" through the system. We do not use such language in standard quantum mechanics. The paper is suspicious, even though it was accepted to a peer-reviewed journal.

If we analyze the classical waves, if we set r = t, then M gets no net force and no photons reach D_2. If we tune r > t, then some photons reach D_2 and M feels a force to the left. Classically, it is not that the flux to D_2 "causes" the net force on M. The tuning causes these two effects.

The authors claim that if we shoot, say, 1 billion photons, and by chance they all end up in D_1, then we can measure no impulse on M to the left. Is that really true?

EDIT: Yes! One billion photons cannot be wrong. The system probably behaves in the experiment like a classical system which produces the same result.

Let us take a simple example. We shoot 1 billion photons through a beam splitter which is just a mirror with a small hole in it. If it happens that all photons pass through without changing their path, then the impulse on the beam splitter is zero. It is like having a beam splitter with a 100% transmission.

Analogously, we may guess that the Aharonov et al. device would behave like classical system where transmission is 50%. Then there is no impulse on M.

Note that if we have a classical wave in the Aharonov device, and the transmission is < 50%, then the intensity at D_2 cannot be zero "by chance". The intensity is always > 0 for a classical wave.

The Aharonov thought experiment shows that, if we by chance, measure the system behaving like a system where transmission is 50%, then the result is like for a classical system where the transmission is 50%. The classical limit imitates what we actually, by chance, measured.

 

[vanhees71]

In the thermal interpretation, the separation into many photons is an illusion, as the real player is the field intensity. Thus the classical analysis given in the paper applies essentially unchanged. The apparent weirdness comes from the erroneous picture that individual photons travel along the beam.

Amazing! The same conclusion is reached in the standard (minimal) interpretation. A classical em. wave (like a laser beam from a usual laser pointer) is quantumtheoretical described as a coherent state, and a naive particle picture of photons a la old quantum theory doesn't make sense to interpret this state. All there is to describe this experiment is the observable momentum flow imposed on the mirror, and what comes out is indeed just the same in QED and CED. Even the calculation is almost the same (as usual in the linear-optical regime you just put hats on your classical fields, and nothing changes).

 

[Heikki Tuuri]

There is an error in how Aharonov et al. interpret the result as showing that photons detected at D2 through some mystical process cause a net push to the left on the mirror M.

Let us change the setup so that we remove the tilted mirror in the up right corner. The ray continues straight there, but we let it reflect from a perfect vertical mirror M2, and place D_1 at the reflection path after the mirror.

Aharonov et al. claim that photons that end up at D_2 somehow mystically push M2 to the right.

Let us imagine a test run where, by chance, all the 1 billion photons we shoot end up being detected at D_2. Is it possible that M2 will feel a force to the right even though D_1 registers no photons? It is clear M2 cannot feel a force. If M2 would absorb an impulse which we can measure, that would amount to measuring a flux of photons impinging on the atoms of M2. It would be a strong measurement of a non-zero flux in the terminology of Aharonov.

Photons that bounce on M2 cannot end up at D_2. We have a contradiction since we assumed that all the photons are detected at D_2 and the flux there is 100%. If the fluxes do not add up to 100%, then conservation of energy is broken.

As mentioned before, our analysis is not limited to interpretational issues. It also serves as a guide for our intuition. Suppose that, by a quantum fluctuation, we receive more than the average number of photons at detector D1. The classical intuition will led us to expect that now the mirror will receive an even larger momentum inwards. Our analysis above tells us differently - since the effect is due to photons going towards D2 and now there are fewer of them, the inward momentum will be smaller.

The above is a quote from the end of the paper. Since the claim is wrong for the case where all the photons are detected at D_2, the claim may be overall wrong.