Polarizing vs nonpolarizing beamsplitter qm toy problems etc

[vzn]

hi all .. I have heard of 3 semiclassicalist proponents,
one of them the established scientist Jaynes, criticize the classic
Grangier,Roger,Aspect (GRA) photon anticorrelation
experiment on the grounds
that it used a polarizing beamsplitter. actually, to be more
specific, (rumor is, at a conference)
Jaynes suggested to Grangier redoing the experiment with circularly
polarized light, which has apparently never been done.

my question: how does QM formalism handle the difference
between a polarizing and "nonpolarizing" beamsplitter?
how does it show up in the mathematics? how does it
change the prediction?

along these lines I was thinking it would be neat to develop
a procedure similar to what is done for electronics components
in intro EE classes & intro textbooks. in these classes, you are given all the
laws for each circuit component & the general principles
for writing equations for their interconnections (based roughly
on F=ma), eg Kierkoff's law.

& then apply it by analyzing/solving for
the whole circuit given in diagram.
this procedure can achieve a high degree of sophistication with
eg links between imaginary number operations & solving
the differential eqns for A/C circuits. the components are
resistors, capacitors, etc.

something similar is done in intro physics classes, with little
toy problems of pendulums, blocks, springs, friction, etc. using F=ma,
conservation of energy, etc

it would be neat to see this done by someone for "toy"/"idealized"
QM elements seen in typical QM papers.
I have never seen this done anywhere. seems one could get quite a bit
of mileage out of it. & also very useful/effective in teaching QM.

(some of these diagrams may be on the web but I can't find one
after a quick google search..maybe will post it later in thread if one
turns up)

refs

[1] excellent online description of the GRA experiment by hans devries
http://chaos.swarthmore.edu/courses/phys6_2004/QM/17_EPR_Bell_Details.pdf

[2] recent undergraduate level GRA experiment, online also, by Thorn et al
http://marcus.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf

tx

vzn

http://groups.yahoo.com/group/qm2/

 

[DrChinese]

hi all .. I have heard of 3 semiclassicalist proponents,
one of them the established scientist Jaynes, criticize the classic
Grangier,Roger,Aspect (GRA) photon anticorrelation
experiment on the grounds
that it used a polarizing beamsplitter.

Grangier and especially Aspect have been through the ringer from the diehard Local Realist/Classicist crowd over the years. Nothing has been too minor to criticize. The fact is, there will ALWAYS be a few who reject the published results for one reason or another. However, these experiments have evolved substantially over the years and have been repeated plenty of times, always yielding the same results as Grangier and Aspect originally presented. They are as accepted as any experiment and meet scientific standards.

Jaynes can say whatever he likes about circular polarized light, that does not change the fact that the classical viewpoint has been clearly rejected. The reason these experiements are picked on is because they shut the door on that viewpoint so tightly.

If someone thinks there is a experiment that proves QM is wrong, well, let's see it. Grangier has indicated those experiments he feels are worth running.

 

[R0man]

The difference between a polarizing and nonpolarizing beamsplitter in QM formalism can be seen in the mathematics through the use of the Jones matrix. The Jones matrix is a 2x2 matrix that describes the polarization state of a beam of light as it passes through an optical element such as a beamsplitter. In the case of a polarizing beamsplitter, the Jones matrix has a specific orientation that only allows light of a certain polarization to pass through, while reflecting light of the opposite polarization. In contrast, a nonpolarizing beamsplitter has a Jones matrix that allows light of all polarizations to pass through with equal probability.

This difference in the Jones matrix can change the prediction of the experiment, as it affects the probability of the photons being split or not split by the beamsplitter. In the GRA experiment, using a polarizing beamsplitter resulted in a correlation between the polarization states of the two photons, while using a nonpolarizing beamsplitter would have resulted in no correlation.

Developing a procedure for analyzing "toy" QM elements in a similar way to how it is done for electronic components in introductory classes could be a useful tool for understanding QM concepts. It could also be effective in teaching QM, as it would provide a visual representation of the principles and equations involved in QM problems.

References [1] and [2] provided in the post offer excellent explanations and examples of the use of the Jones matrix and its effects on the polarization states of light passing through optical elements. It would be interesting to see this approach applied to other QM experiments and concepts.