First quantum crypto bank transfer

Jerrold Leichter jerrold.leichter at smarts.com
Mon Aug 23 06:50:09 EDT 2004


| > The press will always focus on things people understand, and which
| > seem to have short-term relevance. If you're objecting to researchers
| > blowing their own horns ... well, that's the way the world works.
| > It's certainly been the way physics has had to work since it became
| > impossible for an individual, and ultimately even an institution like
| > a university. to be able to fund the experiments necessary to move
| > forward. Without public support, research will starve to death.
|
| 1) There is a difference between
|   -- rightfully blowing one's horn, when one has something to
|    blow about, versus
|   -- lying.
| I object to lying.  Lying includes claiming something has
| short-term relevance when it doesn't.  The blame attaches
| primarily with the mountebanks who originated the lies.
| Blame attaches secondarily to the press for uncritically
| propagating the lies, but that's another matter.
|
| 2) As for "how the world works" ... the real world has means
| for sanctioning people who lie about their work....
I don't really disagree.  *This particular* announcement; indeed, many of the
recent announcements, may well rise to the level of lying - though it's always
important to separate what (a) the researchers said; (b) what some PR flak
turned it into; (c) the hash the press made of it.  However, the comments I've
seen on this list and elsewhere have been much broader, and amount to "QM
secure bit distribution is dumb, it solves no problem we haven't already
solved better with classical techniques."  Even if some snake-oil salesmen
have attached themselves to the field doesn't say research in the field is
worthless.  Should we attack Shannon because some snake-oil salesmen use his
proof of security of one-time pads to "prove" that their (non-OTP) systems are
secure?

Also, there is a world of difference between:

	1.  Showing something is possible in principle;
	2.  Making it work on the lab bench;
	3.  Making it into something that works in the real world.

For QM key exchange, step 1 goes back maybe 10-15 years, and most people
thought it was a curiosity - that you could never maintain coherence except in
free space and over short distances.  Step 2 is a couple of years back, the
first surprise being that you could actually make things work through fiber,
then through a couple of Km of fiber coiled on a bench.  Step 3 is very
recent.  Yes, everyone - including some frauds - are jumping on this right
now.  The first couple of experiments are interesting; beyond that, it's
nothing new.  But look at this from a different point of view:  What are being
solved now are some of the *engineering* problems of distributing coherent QM
states across multi-Km distances in the dirty real world.  Yes, the people who
solve *that* problem usually have no particular strengths at the crypto side;
so, yes, what they are producing today isn't useful, and is oversold.  But it
*may* provide a basis for some so-far-unseen next step.

BTW, if we look at QM *computation* in comparison, we've barely made it
through Step 1.  There are still plausible arguments that you can't maintain
coherence long enough to solve any interesting problems. Some of the papers
I've seen solve the problem only in their titles:  They use a QM system, but
they seem to only make classical bits available for general use.   The
contrast between this work and QM key exchange is striking.  Will the
engineering successes with key exchange somehow feed back to solve some of the
problems with computation?  Perhaps not, but after all, transistors were
invented to build phone lines, not computers!
							-- Jerry

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