View Full Version : *Statistical* communication at a distance at ORNL (?)
Hayden McGuinness
Aug17-04, 11:27 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>\n\nI happened upon this paper, ostensibly written by a researcher at\nORNL, claiming that statistical superluminal communication (that is, I\nassume, communication with some _inherent_ error rate, but I guess\nideally can be made arbitrarily small) is possible and proposes a\nspecific quantum optics implementation. I was curious enough to check\nthis out and as far as I can tell he is truly a researcher at ORNL and\non his site even cites the paper, which I guess is some internal\ndocument. The pdf is at\n\nhttp://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF\n\nand the relevant section is 2. The setup is relatively simple and I\'m\nwondering if someone with quantum optics experience could evaluate his\nclaims. It would be helpful to see the math (more than just what he\ngives, i.e. the progress of the states through the various optical\ncomponents) if this scheme is correct or not.\n\nThanks,\nHayden\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>I happened upon this paper, ostensibly written by a researcher at
ORNL, claiming that statistical superluminal communication (that is, I
assume, communication with some _inherent_ error rate, but I guess
ideally can be made arbitrarily small) is possible and proposes a
specific quantum optics implementation. I was curious enough to check
this out and as far as I can tell he is truly a researcher at ORNL and
on his site even cites the paper, which I guess is some internal
document. The pdf is at
http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF
and the relevant section is 2. The setup is relatively simple and I'm
wondering if someone with quantum optics experience could evaluate his
claims. It would be helpful to see the math (more than just what he
gives, i.e. the progress of the states through the various optical
components) if this scheme is correct or not.
Thanks,
Hayden
Ralph Hartley
Aug18-04, 10:34 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>\nHayden McGuinness wrote:\n> I happened upon this paper, ostensibly written by a researcher at\n> ORNL, claiming that statistical superluminal communication\n....\n> The pdf is at\n>\n> http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF\n>\n> and the relevant section is 2. The setup is relatively simple\n\nI found that to be an interesting puzzle. Sort of like figuring out some of\nthe more subtle perpetual motion machines. You *know* it can\'t work, but it\ncan be fun to see where the trick is.\n\nIn this case the relevant part is the left half of their Figure 1, which\npurports to distinguish a superposition of polarizations from a mixture.\n\nSplitter\nPolarizer\n___\n|\\ | \\\nIn->--|-\\-|---------------\\\n|_|\\| |\\\n| |\n__|__ 90 degree |\n| | |Polarization |\n|__|__|Rotator |\n| |\n\\| \\|\n\\-----------------\\---->A\n\\ |\\\n|\nV\nB\n\nThe idea is that if a photon in a superposition of polarizations enters,\nthe splitter separates the two components, then the rotator changes one of\nthem so that they both have the same polarization. After recombining at the\nlast partial mirror, it is impossible to tell which path it took, so you\nshould get interference. Adjusting the path lengths, you can get all the\nlight to go to A and none to B.\n\nHowever, if the photon is in a mixed state (it is actually polarized one\nway or the other, the experimenter doesn\'t know which, but someone else\nmight know) then it must go one way or the other, and no interference is\npossible. The probability of coming out at A and B are equal.\n\nIndeed, if the device worked as described above, then superluminal\ncommunication would be possible, with an error rate as low as one liked.\n\nOf course the device does *not* work as described!\n\nWhen I started this email, I intended to say why it doesn\'t, but now I have\ndecided not to spoil the fun.\n\nRalph Hartley\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>Hayden McGuinness wrote:
> I happened upon this paper, ostensibly written by a researcher at
> ORNL, claiming that statistical superluminal communication
....
> The pdf is at
>
> http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF
>
> and the relevant section is 2. The setup is relatively simple
I found that to be an interesting puzzle. Sort of like figuring out some of
the more subtle perpetual motion machines. You *know* it can't work, but it
can be fun to see where the trick is.
In this case the relevant part is the left half of their Figure 1, which
purports to distinguish a superposition of polarizations from a mixture.
Splitter
Polarizer
___
|\ | \In->--|-\-|---------------\|_|\| |\| |
__|__ 90 degree |
| | |Polarization |
|__|__|Rotator |
| |\| \|
\-----------------\---->A
\ |\
|
V
B
The idea is that if a photon in a superposition of polarizations enters,
the splitter separates the two components, then the rotator changes one of
them so that they both have the same polarization. After recombining at the
last partial mirror, it is impossible to tell which path it took, so you
should get interference. Adjusting the path lengths, you can get all the
light to go to A and none to B.
However, if the photon is in a mixed state (it is actually polarized one
way or the other, the experimenter doesn't know which, but someone else
might know) then it must go one way or the other, and no interference is
possible. The probability of coming out at A and B are equal.
Indeed, if the device worked as described above, then superluminal
communication would be possible, with an error rate as low as one liked.
Of course the device does *not* work as described!
When I started this email, I intended to say why it doesn't, but now I have
decided not to spoil the fun.
Ralph Hartley
<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>Ralph Hartley:\n\nhttp://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF\n<Of course the device does *not* work as described!>\n\nThe device does not work at all, I suppose.\nBut if it does not work, it means that it is\nirrelevant whether, on the right side, you set\nthe switch on or off. The outcome, on the left\nside, is the same. Is that correct?\ns.\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>Ralph Hartley:
http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF
<Of course the device does *not* work as described!>
The device does not work at all, I suppose.
But if it does not work, it means that it is
irrelevant whether, on the right side, you set
the switch on or off. The outcome, on the left
side, is the same. Is that correct?
s.
Ralph Hartley
Aug24-04, 04:52 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>scerir wrote:\n> Ralph Hartley:\n>\n> http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF\n> <Of course the device does *not* work as described!>\n>\n> The device does not work at all, I suppose.\n> But if it does not work, it means that it is\n> irrelevant whether, on the right side, you set\n> the switch on or off. The outcome, on the left\n> side, is the same. Is that correct?\n\nThat is correct.\n\nThe puzzle is to determine which outcome that is, and why.\n\nRalph Hartley\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>scerir wrote:
> Ralph Hartley:
>
> http://accelconf.web.cern.ch/AccelConf/p01/PAPERS/TPPH041.PDF
> <Of course the device does *not* work as described!>
>
> The device does not work at all, I suppose.
> But if it does not work, it means that it is
> irrelevant whether, on the right side, you set
> the switch on or off. The outcome, on the left
> side, is the same. Is that correct?
That is correct.
The puzzle is to determine which outcome that is, and why.
Ralph Hartley
Hayden McGuinness
Aug24-04, 04:55 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>I believe the matter would be cleared up rather quickly if we just do\nthe math. The problem for me is that I don\'t know what some of the\noperators are. For example, we are starting out with the state (I\nwon\'t bother to normalize) phi =|A:1>|B:0> +|A:0>|B:1>, where A and B\nare the different paths (left and right really), and 1 and 0 are horz\nand vert. Now, if the A path has a 90 degree rotator for both\npolarizations (no polarizing beam splitter) ,then (I think), the new\nstate becomes phi =|A:0>|B:0> +|A:1>|B:1>, right? Also, if there is a\n\\pi phase shifter in path A then the state because phi = -|A:0>|B:0>\n-|A:1>|B:1> . Now, we just need to see what all the operations make\nthe final state in. Problem is I don\'t know exactly what interference\nmathematically, with these quantum states, is. When do we say there is\ninterference and the photons go to detector A or B, what does this\nstate look like? Also, I\'m not quite sure what semi-transparent mirror\ndoes, in mathematical language (it seems like it would just be beam\nsplitter, although then there would just be beam splitter in the\ndiagram).\n\nBy the way, I don\'t think it is *clear* that this scheme should not\nwork; after all it\'s not truly communication at a distance since,\nthere is an *inherent error rate*, and no violation of relativity is\nproduced. For example, I don\'t think anyone quibbles with the claim\nthat we can do communication at a distance with an error rate of 50%.\n:}\n\nHayden\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>I believe the matter would be cleared up rather quickly if we just do
the math. The problem for me is that I don't know what some of the
operators are. For example, we are starting out with the state (I
won't bother to normalize) \phi =|A:1>|B:0> +|A:0>|B:1>, where A and B
are the different paths (left and right really), and 1 and are horz
and vert. Now, if the A path has a 90 degree rotator for both
polarizations (no polarizing beam splitter) ,then (I think), the new
state becomes \phi =|A:0>|B:0> +|A:1>|B:1>, right? Also, if there is a
\pi phase shifter in path A then the state because \phi = -|A:0>|B:0>-|A:1>|B:1> . Now, we just need to see what all the operations make
the final state in. Problem is I don't know exactly what interference
mathematically, with these quantum states, is. When do we say there is
interference and the photons go to detector A or B, what does this
state look like? Also, I'm not quite sure what semi-transparent mirror
does, in mathematical language (it seems like it would just be beam
splitter, although then there would just be beam splitter in the
diagram).
By the way, I don't think it is *clear* that this scheme should not
work; after all it's not truly communication at a distance since,
there is an *inherent error rate*, and no violation of relativity is
produced. For example, I don't think anyone quibbles with the claim
that we can do communication at a distance with an error rate of 50%.
:}
Hayden
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