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
--
http://www.God-does-not-play-dice.net
http://www.God-does-not-play-dice.net/download.html
 

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
March 24, 2005
Last update: February 1, 2006

 

============

Subject: ... not with certainty but without disturbing the measured system?
Date: Wed, 01 Feb 2006 15:10:27 +0200
From: Dimi Chakalov <dimi@chakalov.net>
To: Norbert Luetkenhaus <luetkenhaus@pi5240.physik.uni-erlangen.de>
CC: Miloslav Dusek <dusek@optics.upol.cz>,
     Martin Hendrych <hendrych@sloup.upol.cz>

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
--
http://www.God-does-not-play-dice.net
http://www.God-does-not-play-dice.net/download.html

[Ref. 1] Miloslav Dusek, Norbert Lutkenhaus, Martin Hendrych, Quantum
Cryptography, quant-ph/0601207 v1.
http://arxiv.org/abs/quant-ph/0601207

"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.
...
"It should be noted that quantum mechanics does not avert eavesdropping; it only enables us to detect the presence of an eavesdropper. Since only the cryptographic key is transmitted, no information leak can take place when someone attempts to listen in. When discrepancies are found, the key is simply discarded and the users repeat the procedure to generate a new key.
...
"Eavesdropping is nothing else than a kind of measurement on the information carrier. If non-orthogonal states are used in transmission, eavesdropping must disturb some of them, i.e. induce errors."

============

Subject: Re: ... not with certainty but without disturbing the measured system?
From: Dimi Chakalov <dimi@chakalov.net>
Date: Wed, 01 Feb 2006 18:17:07 +0200
To: Norbert Lütkenhaus <nlutkenhaus@iqc.ca>
CC: Miloslav Dusek <dusek@optnw.upol.cz>,
Martin Hendrych <hendrych@optnw.upol.cz>

Dear Norbert,

Thank you for your prompt reply. Sorry for not writing your name correctly in my preceding email.

> it is possible for Eve to listen to Alice and Bob without disturbing the
> system if she is lucky. However, the probability for this to happen can
> be made exponentially small in the security paramter (number of signals).
> The ususal security analyses take care of that (see e.g. the paper by
> Inamori, NL, and Mayers).
>
> I guess, this is what you are hinting at?

Jain. Yes -- because there is a possibility for Eve that can be made exponentially small, but not zero (especially in a huge network). No -- because what I meant was a non-demolition "measurement" that does not produce any "collapse" whatsoever: Eve just connects to your brain(s) and does copy&paste without you being aware (do you know Sheldrake's morphogenetic field?). She cannot be certain that her "copies" are genuine, of course, but with a little luck ... and your cryptography is for the birds.

See how your brain works at

http://www.God-does-not-play-dice.net/Rosinger.html

[snip]

Regards,

Dimi
 

============

Subject: Non-relativistic quantum bit string commitment?
Date: Thu, 05 Jun 2003 13:48:43 +0300
From: Dimi Chakalov <dchakalov@surfeu.at>
To: Adrian Kent <a.p.a.kent@damtp.cam.ac.uk>
CC: mermin@ccmr.cornell.edu, bennetc@watson.ibm.com,
     divince@watson.ibm.com, peres@photon.technion.ac.il,
     a.steane1@physics.ox.ac.uk, artur.ekert@qubit.org,
     tapster@falcor.dera.gov.uk, lkgrover@lucent.com,
     William.K.Wootters@williams.edu, shor@research.att.com,
     slloyd@mit.edu, p.knight@ic.ac.uk, m.plenio@ic.ac.uk
 

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
http://members.aon.at/chakalov
--
Dead matter makes quantum jumps; the living-and-quantum matter is smarter.