Photon Polarization / Superposition of States

We can ask ourselves what the subject ‘looks like’, at the single-particle level, of polarized light. We know that at the level of wave-mechanics, both plane-polarized and circularly-polarized light are easy to understand: Either way, the dipole-moments are at right angles to the direction of propagation, all the time, even if randomly so. But there also needs to be a particle / photon -based explanation for all the properties of light, in order to satisfy the demands of Quantum Mechanics.

And so a key question could be phrased as, ‘If we pass randomly-polarized light through a simple linear polarizer, which consists of a gel-block, and which absorbs EM vibrations along one disfavored axis, maybe because it has been made ohmic along that axis, why is the maximum intensity of plane-polarized light that comes out, in fact so close to 50% of the intensity, of the randomly-polarized beam that went in?’ Using wave-mechanics, the answer is easy to see, but using particle-physics, the answer is not so obvious.

And one reason fw the answer may not be obvious, is because we might be visualizing each photon, as being plane-polarized at an angle unique to itself. In that case, if the polarizer only transmits light, which is polarized to an extremely pure degree, the number of photons whose plane of polarization lines up with the favored angle perfectly, should be few-to-none. Each photon could then have an angle of polarization, which is not exactly lined up with the axis which the polarizer favors, and would thus be filtered out. And yet, the strength of the electric dipole-moment which comes out of the polarizer, along the disfavored axis, could be close to zero, while the total amount of light that comes out, could be close to 50% of how much light came in.

If each incident photon had been plane-polarized in one random direction, then surely fewer than 50% of them, would have been polarized, in one exact direction.

(Updated 04/10/2018 … )

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How Accuracy-Of-Prediction may not be Adequate Proof.

What modern people may be tempted to think, is that if a hypothesis exists, which predicts real-world events with great precision, this hypothesis must also be a true statement, of how the real world operates. And I’d like to point out a Historic example, where this was not the case. That example, was the Ptolemaic system of Astronomy.

This system of Astronomy taught, since thousands of years, that the stars in the nighttime sky are attached to rotating shells, which are somehow pinned to the Earth’s axis, as well as being hinged to each other. Thereby, certain stars now known as fixed stars, would exist as belonging to one such shell, while other stars which are now known as planets of our own Solar System, exist as belonging to an additional shell, which is rotating around the first shell, I described, along an additional axis.

What modern people may not see, is that this system was able to predict with extreme precision, where each planet or star was going to appear, at any point in time, which in turn was seen as adequate proof, that the system was ‘true’.

In fact, when Nikolaus Copernicus suggested that the planets, including the Earth, in fact orbit our Sun, his model had a weakness: The Copernican hypothesis suggested circular orbits. And what this did, was to produce inaccuracies, with respect to the observable positions of each planet, over which the Ptolemaic system was far more accurate.

This weakness was only corrected by Johannes Kepler, who discovered that the orbits of the planets are elliptical. Making these orbits elliptical, made them consistent both with Newtonian Physics and Newtonian Gravity, as well as with the observable positions of planets in the nighttime sky.

And so a precedence exists, where a system of ideas was presented, which was extremely accurate in its numerical predictions, but which was ultimately false. I strongly suspect that today’s notions of Quantum Mechanics are a repeat of that.

Dirk

 

Hypothesis Disproved

A linear polarizer which I had ordered on-line recently arrived, and I did a promised experiment today, to test a hypothesis.

Hypothesis:

In This earlier posting and This earlier posting, I had proposed what amounts to two hypotheses combined:

  1. That photons may be circularly-polarized as one of their fundamental states, specifically left-handedly or right-handedly, so that other states of light can emerge from those states, eventually also due to a superposition of these two, intrinsic states.
  2. That quantum superposition can generally be collapsed, after which it will not resume as such, but after which witnessing of the resulting state may still take place.

The second hypothesis was meant as a synonym, for stating that:

  • Quantum-Mechanics is to take a form, in which certain states of particles are primary, while others are secondary, so that the secondary states can only form from the superposition of the primary states, while the reverse does not follow. This paraphrasing of the second hypothesis was further meant as a motivation to test, whether the particle-nature of matter and energy are in fact primary – hence, the circularly-polarized photons – and not the wave-nature.

Equipment used in the experiment:

A circular polarizer: A complex component, which has the logical operations of filtering light first, so that only light whose wave-function is plane-polarized along one axis is transmitted, and then secondly, to circularly-polarize the resulting light, so that its wave-functions along any two axes will be phase-shifted 90⁰ with respect to time. This was meant as a source for a primary state of light, polarized in an unknown direction out of two possible directions, since the retail store that sold me this circular polarizer, also did not label, whether it would produce left-handed or right-handed light. It’s to serve as a sufficiently-reliable source of circularly-polarized light.

A linear polarizer: A technically simpler component, which simply transmits light whose wave-function is plane-polarized along one axis, while absorbing light, whose wave-function is perpendicular to the plane transmitted. This was meant as an alternative, secondary state of light, formed as the superposition of left-handed and right-handed, circularly-polarized light.

A light-source: To consist of a mundane room-lighting fixture, which is assumed to generate randomly-polarized light.

Comments:

  1. The matter will be regarded as trivial, that when stating ‘the wave function’, I am referring to ‘the electrostatic wave-function’, which is assumed to be perpendicular to the magnetic wave-function, while also being in-phase with it at all times.
  2. The question will be ignored, whether the circular polarizer itself physically consists of two distinct layers, that perform its logical operations one-by-one, or whether it is of some other design, that accomplishes the same logical operations in some other way.

Procedure:

Control:

Light from the light-source will first be passed through the linear polarizer, and then through the circular polarizer, to confirm that two axes of plane-polarized light, when perpendicular, will lead to near-zero overall transmission, while when they are parallel, will lead to maximum transmission, which will also be used as the notional reference, corresponding to ‘50% transmission’.

Test-Case:

Light from the light-source will first be passed through the circular polarizer, the output of which is somehow to correspond to photons polarized in one circular direction, after which it will be passed to the linear polarizer.

Expected Result:

Because according to the hypotheses, the circularly-polarized light corresponds to an intrinsic state, which will no longer become superposed with the opposite state, the second component, the linear polarizer in the test-case, should not be able to output linearly- or plane-polarized light, because to do so should require the availability of both left- and right-handed photons. But, the linear polarizer will only receive a full amplitude of one or the other.

Real results:

Control:

The control case performed as expected.

Test-Case:

In the test-case, regardless of what orientation was chosen between the two polarizers, light emerged from the last, with constant brightness corresponding to ‘50% transmission’.

Conclusion:

While the principal is to be upheld, that circularly-polarized light may be one system for stating polarization, out of which plane-polarized light can emerge, eventually through quantum superposition, the reverse also seems to be possible.

However, this does not seem to favor an intrinsic state, as belonging to classical concepts of a particle, because the wave-function can be manipulated, regardless of the eventual existence of particles. And so this result further seems to suggest that wave-particle duality is plausible.

(Further Observations as of 02/24/2018 : )

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The Myth of Wave / Particle Duality

This posting describes some of the History, which many people may be bypassing, in their appreciation of Quantum Mechanics.

About until the 1920s, ‘light’ was largely thought to consist of waves. But a problem with that was, how to explain, why light can travel through apparently empty space. After all, the light that reaches us from distant stars is not fundamentally different, from light that originates on Planet Earth. And until the 1920s, it was believed that there exists a mysterious “Aether“, which transmitted light through space.

A basic premise of wave-propagation, such as in the case of sound-waves, is that there must first be some sort of medium, to conduct the waves, which in the case of sound may be air. But the need for the existence of a medium, also explains why there is no sound in space.

But during the 1920s, the existence of an aether was disproved. Decisively. And so another explanation was needed, of what constitutes light. And the thought seemed more logical, that particles can easily travel through empty space – hence, photons. Even though this was not actually the first form in which photons were theorized.

But then obviously, this raises questions, about how these particles are supposed to relate to waves, where waves were at first easier to observe.

I think that the way many people today are presented, what Quantum-Mechanics consists of, is just, “Wave / Particle Duality”. But then what many students believe – and what I once believed myself – is, that Quantum Mechanics holds some sort of secret key, as to how Matter and Energy might simultaneously consist of particles and waves. And in reality, QM holds no such decisive, secret answers. The only real secret which QM may hold, is a detail that could be embarrassing to the present way in which QM works.

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