| Subject: Causal quantum theory
Date: Thu, 24 Mar 2005 16:35:23 +0200 From: Dimi Chakalov <dimi@chakalov.net> To: Adrian Kent <A.P.A.Kent@damtp.cam.ac.uk> CC: Nicolas.Gisin@physics.unige.ch, ppearle@hamilton.edu, a.steane1@physics.ox.ac.uk, celliott@bbn.com Dear Adrian, Regarding your quant-ph/0204104 v3: It seems to me that, for causal quantum theory to be right, and yet not to have been detected in Bell experiments to date, you need the putative global mode of spacetime, http://www.God-does-not-play-dice.net/Tresser.html#collapse You also wrote: "It would be fascinating to see the experiments done, even if they do no more than remove a sliver of doubt. One hopes they will be, once technology allows suitably long range distribution of entanglement." Are you implying that *non-relativistic* quantum bit string commitment is indeed possible?:-) See my email from Thu, 05 Jun 2003 13:48:43 +0300 at http://www.God-does-not-play-dice.net/Adrian.html Regards, Dimi Chakalov
Note: There is nothing certain in non-relativistic QM and hence in quantum communications. This simple statement is known since 1935, and is rooted on Kochen-Specker theorem. If you wish to share your secrets, try first to eliminate the uncertainty in the relativistic "collapse". Briefly, I think non-demolition "measurements" are indeed possible, although not with certainty. As to the technology that would allow
"suitably long range distribution of entanglement", as Adrian Kent hopes,
look no further than your brain, then see what
Adrian Kent has missed in his "Night
Thoughts" below.
D. Chakalov
============ Subject: ...
not with certainty but without disturbing the measured system?
Dear Dr. Luetkenhaus, I wonder if you can play devil's advocate by suggesting a possibility for Eve to listen to Bob & Alice -- not with certainty but without disturbing the measured system [Ref. 1]. I'm afraid this might be possible. Regards, Dimi Chakalov
[Ref. 1] Miloslav
Dusek, Norbert Lutkenhaus, Martin Hendrych, Quantum
"The principle of quantum cryptography
consists in the use of non-orthogonal quantum states. Its security is guaranteed
by the Heisenberg uncertainty principle, which does not allow us to discriminate
non-orthogonal states with certainty and without disturbing the measured
system.
============
Subject: Re: ... not with certainty but without
disturbing the measured system? ============ Subject: Non-relativistic quantum
bit string commitment?
Dear Adrian, Let me set the record straight. Four years ago, in June 1999, I wrote you regarding your "Night Thoughts of a Quantum Physicist", physics/9906040. You politely asked me NOT to send you email, which prevented me from explaining to you some serious errors in your exercise. I'm reading another edition of your 'night thoughts', this time on quantum cryptography, "Quantum Bit String Commitment", quant-ph/0111099. You've been working on it since November 2001 and posted the final published version on Wed, 4 Jun 2003 16:55:51 GMT. It seems to me that you still deeply believe that *non-relativistic* quantum bit string commitment is indeed possible, and suggest "an extra layer of classically unobtainable security with a partial but unconditional security guarantee." Suppose you want to tight your bike to a tree so that nobody can steal it. You can use a good classical iron chain and pray that nobody would like your bike enough to break the chain. Then you add "an extra layer" (see above), "while restricting the amount of information B can obtain". All of the above, however, is based on the interpretation of QM adopted in your community, http://members.aon.at/chakalov/Mermin.html#note Well, make sure you bike is very old and rusty, like those in Amsterdam, and nobody would really like it. Please don't feel obliged to reply, I'm writing this mainly for the readers of my CD ROM "Physics of Human Intention". Needless to say, I will be happy to send you the disk, provided you will try to find my errors. I extend this offer to all recipients of this email. Regards, Dimi
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