Schneibster
Nov25-04, 03:39 AM
<jabberwocky><div class="vbmenu_control"><a href="jabberwocky:;" onClick="newWindow=window.open('','usenetCode','toolbar=no, location=no,scrollbars=yes,resizable=yes,status=no ,width=650,height=400'); newWindow.document.write('<HTML><HEAD><TITLE>Usenet ASCII</TITLE></HEAD><BODY topmargin=0 leftmargin=0 BGCOLOR=#F1F1F1><table border=0 width=625><td bgcolor=midnightblue><font color=#F1F1F1>This Usenet message\'s original ASCII form: </font></td></tr><tr><td width=449><br><br><font face=courier><UL><PRE>Hi, I\'ve been honing this idea for about 3 or 4 months, and now I\'d like\nto bring it here and discuss it. I\'ll start out by stating that I am not\na professional physicist; I have been studying physics on an amateur\nbasis for most of my life, so most of my knowledge is from various\ngeneral-reader-level books. However, I do have a degree in electronics\nengineering, so hopefully I will not make a complete fool of myself\nhere.\n\nAs a review, the Delayed Choice quantum eraser was proposed by Scully\nand Drühl in \'this\' (http://prola.aps.org/abstract/PRA/v25/i4/p2208_1)\narticle, and then performed by Kim, Kulik, Shih, and Scully in 1999 as\nreported in \'this\'\n(http://xxx.lanl.gov/PS_cache/quant-ph/pdf/9903/9903047.pdf) article.\nBasically, photons are led through a dual-slit apparatus, and then\nsplit with a β-BBO crystal spontaneous parametric down-converter\n(SPDC) into orthogonally-polarized pairs that are separated with a\nGlan-Thompson prism and sent to two separate measurement areas.\n\nIn the first area, the photons are allowed to fall on a movable\ndetector that checks various positions for photon count. This is\nessentially looking for interference fringes, which would show up as\nhigh incidences at some locations and low or zero incidences at others.\nThese photons are labeled "signal" photons in the 1999 paper.\n\nIn the second measurement area, the photons are either captured by one\nof two detectors that determine their "which-path" data, which is valid\nfor determination of the which-path data for their associated signal\nphoton, or are sent to a "scrambler" that makes it impossible to\nreclaim the which-path data from them. These are labeled as "idler"\nphotons in the 1999 paper. The scrambler is labeled as a "quantum\neraser" in the 1982 paper.\n\nThe "Delayed Choice" is introduced by making the path to the idler\nmeasurement area longer than the path to the signal measurement area.\n\n\nThe experimenters report that, after correlation, the collection of\nsignal photons that are correlated with idler photons that went to the\nquantum eraser show interference, whereas the collection of signal\nphotons that are correlated with idler photons that went to the\nwhich-path determination detectors do not show interference.\n\nBy conventional causality, because\na) No matter what we do to the signal photons, the idler photons are\nunaffected as far as we can tell,\nbut\nb) depending on whether we measure the which-path information we do or\ndo not see interference in the signal photons,\nwe interpret the idler photon measurement or non-measurement of\nwhich-path information as the "cause" and non-interference or\ninterference as the "effect." Therefore, by that conventional\ninterpretation, this experiment appears to violate the normal time\ndirection of causes preceding effects.\n\nI wondered whether it might be possible to make this time reversal\nexplicit. My direction of attack was to attempt to differentiate the\ninterference case from the non-interference case -without resort to the\ncorrelation, or in fact to any measurement of the idler photons.-\n\nAfter developing this into something like a paper or proposal, I\nrealized that I had forgotten to consider that the superposition of the\ninterference patterns detected in the initial experiment might add up to\nthe non-interference case. After spending some time being frustrated at\nsuch an oversight, I evaluated the published experimental results, and\nfound that\na) they are not sufficiently detailed to absolutely confirm or deny\nthat there is a difference between the interference and\nnon-interference patterns,\nbut\nb) they tend to indicate that there will be a difference.\n\nThe original experimental data were not published, but from the two\nfigures that show the interference cases, and the figure that shows the\nnon-interference case, I obtained the following values for photon impact\ncount, working from left to right across the graphs and giving the\nimpact count at each data point:\nFigure 3:\n17 21 27 19 26 36 61 81 99 87 46 35 56 77 110 121 123 55 43 33 41 66 60\n58 18 12 14 11\nFigure 4:\n18 16 18 33 63 56 37 33 32 55 79 117 123 94 60 42 56 82 103 94 72 38 28\n39 29 40 21 17\nThe two figures added together:\n35 37 45 52 89 92 98 114 131 148 125 152 179 171 170 163 179 137 146\n127 113 104 88 97 47 52 35 28\nAnd last, the sequence from Figure 5:\n16 35 50 71 96 103 123 98 119 102 103 91 49 36 41\nNote that the data from figures 3 and 4 is taken at 0.1mm (100μm)\nintervals, whereas the data for figure 5 is at 0.2mm (200μm)\nintervals.\n\nThe trough-to-peak difference in local minima and maxima of impacts\nappears to be 17-25% of the maximum for the non-interference case, but\n23-30% for the interference case. In addition, there are many more\napparent "deviations" from the best curve in the interference case than\nin the non-interference case. However, as I noted above, the data appear\nto be too sparse to absolutely rule out the possibility that they cannot\nbe distinguished from one another.\n\nMy proposal is therefore as follows:\n1. Replace the stepper-motor-driven detector with a CCD array that can\nread single lines. Such arrays \'exist\'\n(http://naysika.mi.iasf.cnr.it/epic/pnfocalplane.htm) and if properly\noriented would allow the detection of evidence of interference fringes\nvery quickly, if combined with appropriate electronics and fast image\nprocessing.\n2. Use optical delay lines, preferably variable switched delay lines\nwith external fiber-optic hookups to facilitate the use of measured\ncable lengths to introduce the desired delay.\n3. Replace the beam splitters that randomly direct one half of the\nidler photons to the eraser, and the other half to the which-path\ndetectors, with LCD optical switches. Such switches are currently in\nuse in optical networking switches available from over fifty companies\nworldwide.\n\nI would begin by attempting to successfully differentiate the\ninterference pattern from the non-interference pattern. If this were\nsuccessful, then I would proceed with attempting to apply negative\nfeedback to the experiment, in which the detection of interference\nwould cause the measurement of the idler photons\' which-path\ninformation, and detection of non-interference would cause the idler\nphotons to be sent to the eraser.\n\nI seek opinions on whether this experiment is possible (i.e., whether\nthe interference and non-interference cases can be differentiated), and\non what the results might be if it -is- possible, and on what might\nhappen if it is possible and negative feedback is applied.\n\n------------------------------------------------------------------------\nThis post submitted through the LaTeX-enabled physicsforums.com\nTo view this post with LaTeX images:\nhttp://www.physicsforums.com/showthread.php?t=53899#post380482\n\n</UL></PRE></font></td></tr></table></BODY><HTML>');"> <IMG SRC=/images/buttons/ip.gif BORDER=0 ALIGN=CENTER ALT="View this Usenet post in original ASCII form"> View this Usenet post in original ASCII form </a></div><P></jabberwocky>Hi, I've been honing this idea for about 3 or 4 months, and now I'd like
to bring it here and discuss it. I'll start out by stating that I am not
a professional physicist; I have been studying physics on an amateur
basis for most of my life, so most of my knowledge is from various
general-reader-level books. However, I do have a degree in electronics
engineering, so hopefully I will not make a complete fool of myself
here.
As a review, the Delayed Choice quantum eraser was proposed by Scully
and Drühl in 'this' (http://prola.aps.org/abstract/PRA/v25/i4/p2208_1)
article, and then performed by Kim, Kulik, Shih, and Scully in 1999 as
reported in 'this'
(http://xxx.lanl.gov/PS_cache/quant-ph/pdf/9903/9903047.pdf) article.
Basically, photons are led through a dual-slit apparatus, and then
split with a β-BBO crystal spontaneous parametric down-converter
(SPDC) into orthogonally-polarized pairs that are separated with a
Glan-Thompson prism and sent to two separate measurement areas.
In the first area, the photons are allowed to fall on a movable
detector that checks various positions for photon count. This is
essentially looking for interference fringes, which would show up as
high incidences at some locations and low or zero incidences at others.
These photons are labeled "signal" photons in the 1999 paper.
In the second measurement area, the photons are either captured by one
of two detectors that determine their "which-path" data, which is valid
for determination of the which-path data for their associated signal
photon, or are sent to a "scrambler" that makes it impossible to
reclaim the which-path data from them. These are labeled as "idler"
photons in the 1999 paper. The scrambler is labeled as a "quantum
eraser" in the 1982 paper.
The "Delayed Choice" is introduced by making the path to the idler
measurement area longer than the path to the signal measurement area.
The experimenters report that, after correlation, the collection of
signal photons that are correlated with idler photons that went to the
quantum eraser show interference, whereas the collection of signal
photons that are correlated with idler photons that went to the
which-path determination detectors do not show interference.
By conventional causality, because
a) No matter what we do to the signal photons, the idler photons are
unaffected as far as we can tell,
but
b) depending on whether we measure the which-path information we do or
do not see interference in the signal photons,
we interpret the idler photon measurement or non-measurement of
which-path information as the "cause" and non-interference or
interference as the "effect." Therefore, by that conventional
interpretation, this experiment appears to violate the normal time
direction of causes preceding effects.
I wondered whether it might be possible to make this time reversal
explicit. My direction of attack was to attempt to differentiate the
interference case from the non-interference case -without resort to the
correlation, or in fact to any measurement of the idler photons.-
After developing this into something like a paper or proposal, I
realized that I had forgotten to consider that the superposition of the
interference patterns detected in the initial experiment might add up to
the non-interference case. After spending some time being frustrated at
such an oversight, I evaluated the published experimental results, and
found that
a) they are not sufficiently detailed to absolutely confirm or deny
that there is a difference between the interference and
non-interference patterns,
but
b) they tend to indicate that there will be a difference.
The original experimental data were not published, but from the two
figures that show the interference cases, and the figure that shows the
non-interference case, I obtained the following values for photon impact
count, working from left to right across the graphs and giving the
impact count at each data point:
Figure 3:
17 21 27 19 26 36 61 81 99 87 46 35 56 77 110 121 123 55 43 33 41 66 60
58 18 12 14 11
Figure 4:
18 16 18 33 63 56 37 33 32 55 79 117 123 94 60 42 56 82 103 94 72 38 28
39 29 40 21 17
The two figures added together:
35 37 45 52 89 92 98 114 131 148 125 152 179 171 170 163 179 137 146
127 113 104 88 97 47 52 35 28
And last, the sequence from Figure 5:
16 35 50 71 96 103 123 98 119 102 103 91 49 36 41
Note that the data from figures 3 and 4 is taken at .1mm (100μm)
intervals, whereas the data for figure 5 is at .2mm (200μm)
intervals.
The trough-to-peak difference in local minima and maxima of impacts
appears to be 17-25% of the maximum for the non-interference case, but
23-30% for the interference case. In addition, there are many more
apparent "deviations" from the best curve in the interference case than
in the non-interference case. However, as I noted above, the data appear
to be too sparse to absolutely rule out the possibility that they cannot
be distinguished from one another.
My proposal is therefore as follows:
1. Replace the stepper-motor-driven detector with a CCD array that can
read single lines. Such arrays 'exist'
(http://naysika.mi.iasf.cnr.it/epic/pnfocalplane.htm) and if properly
oriented would allow the detection of evidence of interference fringes
very quickly, if combined with appropriate electronics and fast image
processing.
2. Use optical delay lines, preferably variable switched delay lines
with external fiber-optic hookups to facilitate the use of measured
cable lengths to introduce the desired delay.
3. Replace the beam splitters that randomly direct one half of the
idler photons to the eraser, and the other half to the which-path
detectors, with LCD optical switches. Such switches are currently in
use in optical networking switches available from over fifty companies
worldwide.
I would begin by attempting to successfully differentiate the
interference pattern from the non-interference pattern. If this were
successful, then I would proceed with attempting to apply negative
feedback to the experiment, in which the detection of interference
would cause the measurement of the idler photons' which-path
information, and detection of non-interference would cause the idler
photons to be sent to the eraser.
I seek opinions on whether this experiment is possible (i.e., whether
the interference and non-interference cases can be differentiated), and
on what the results might be if it -is- possible, and on what might
happen if it is possible and negative feedback is applied.
------------------------------------------------------------------------
This post submitted through the LaTeX-enabled physicsforums.com
To view this post with LaTeX images:
http://www.physicsforums.com/showthread.php?t=53899#post380482
to bring it here and discuss it. I'll start out by stating that I am not
a professional physicist; I have been studying physics on an amateur
basis for most of my life, so most of my knowledge is from various
general-reader-level books. However, I do have a degree in electronics
engineering, so hopefully I will not make a complete fool of myself
here.
As a review, the Delayed Choice quantum eraser was proposed by Scully
and Drühl in 'this' (http://prola.aps.org/abstract/PRA/v25/i4/p2208_1)
article, and then performed by Kim, Kulik, Shih, and Scully in 1999 as
reported in 'this'
(http://xxx.lanl.gov/PS_cache/quant-ph/pdf/9903/9903047.pdf) article.
Basically, photons are led through a dual-slit apparatus, and then
split with a β-BBO crystal spontaneous parametric down-converter
(SPDC) into orthogonally-polarized pairs that are separated with a
Glan-Thompson prism and sent to two separate measurement areas.
In the first area, the photons are allowed to fall on a movable
detector that checks various positions for photon count. This is
essentially looking for interference fringes, which would show up as
high incidences at some locations and low or zero incidences at others.
These photons are labeled "signal" photons in the 1999 paper.
In the second measurement area, the photons are either captured by one
of two detectors that determine their "which-path" data, which is valid
for determination of the which-path data for their associated signal
photon, or are sent to a "scrambler" that makes it impossible to
reclaim the which-path data from them. These are labeled as "idler"
photons in the 1999 paper. The scrambler is labeled as a "quantum
eraser" in the 1982 paper.
The "Delayed Choice" is introduced by making the path to the idler
measurement area longer than the path to the signal measurement area.
The experimenters report that, after correlation, the collection of
signal photons that are correlated with idler photons that went to the
quantum eraser show interference, whereas the collection of signal
photons that are correlated with idler photons that went to the
which-path determination detectors do not show interference.
By conventional causality, because
a) No matter what we do to the signal photons, the idler photons are
unaffected as far as we can tell,
but
b) depending on whether we measure the which-path information we do or
do not see interference in the signal photons,
we interpret the idler photon measurement or non-measurement of
which-path information as the "cause" and non-interference or
interference as the "effect." Therefore, by that conventional
interpretation, this experiment appears to violate the normal time
direction of causes preceding effects.
I wondered whether it might be possible to make this time reversal
explicit. My direction of attack was to attempt to differentiate the
interference case from the non-interference case -without resort to the
correlation, or in fact to any measurement of the idler photons.-
After developing this into something like a paper or proposal, I
realized that I had forgotten to consider that the superposition of the
interference patterns detected in the initial experiment might add up to
the non-interference case. After spending some time being frustrated at
such an oversight, I evaluated the published experimental results, and
found that
a) they are not sufficiently detailed to absolutely confirm or deny
that there is a difference between the interference and
non-interference patterns,
but
b) they tend to indicate that there will be a difference.
The original experimental data were not published, but from the two
figures that show the interference cases, and the figure that shows the
non-interference case, I obtained the following values for photon impact
count, working from left to right across the graphs and giving the
impact count at each data point:
Figure 3:
17 21 27 19 26 36 61 81 99 87 46 35 56 77 110 121 123 55 43 33 41 66 60
58 18 12 14 11
Figure 4:
18 16 18 33 63 56 37 33 32 55 79 117 123 94 60 42 56 82 103 94 72 38 28
39 29 40 21 17
The two figures added together:
35 37 45 52 89 92 98 114 131 148 125 152 179 171 170 163 179 137 146
127 113 104 88 97 47 52 35 28
And last, the sequence from Figure 5:
16 35 50 71 96 103 123 98 119 102 103 91 49 36 41
Note that the data from figures 3 and 4 is taken at .1mm (100μm)
intervals, whereas the data for figure 5 is at .2mm (200μm)
intervals.
The trough-to-peak difference in local minima and maxima of impacts
appears to be 17-25% of the maximum for the non-interference case, but
23-30% for the interference case. In addition, there are many more
apparent "deviations" from the best curve in the interference case than
in the non-interference case. However, as I noted above, the data appear
to be too sparse to absolutely rule out the possibility that they cannot
be distinguished from one another.
My proposal is therefore as follows:
1. Replace the stepper-motor-driven detector with a CCD array that can
read single lines. Such arrays 'exist'
(http://naysika.mi.iasf.cnr.it/epic/pnfocalplane.htm) and if properly
oriented would allow the detection of evidence of interference fringes
very quickly, if combined with appropriate electronics and fast image
processing.
2. Use optical delay lines, preferably variable switched delay lines
with external fiber-optic hookups to facilitate the use of measured
cable lengths to introduce the desired delay.
3. Replace the beam splitters that randomly direct one half of the
idler photons to the eraser, and the other half to the which-path
detectors, with LCD optical switches. Such switches are currently in
use in optical networking switches available from over fifty companies
worldwide.
I would begin by attempting to successfully differentiate the
interference pattern from the non-interference pattern. If this were
successful, then I would proceed with attempting to apply negative
feedback to the experiment, in which the detection of interference
would cause the measurement of the idler photons' which-path
information, and detection of non-interference would cause the idler
photons to be sent to the eraser.
I seek opinions on whether this experiment is possible (i.e., whether
the interference and non-interference cases can be differentiated), and
on what the results might be if it -is- possible, and on what might
happen if it is possible and negative feedback is applied.
------------------------------------------------------------------------
This post submitted through the LaTeX-enabled physicsforums.com
To view this post with LaTeX images:
http://www.physicsforums.com/showthread.php?t=53899#post380482