QIP – Post 2

The afternoon’s talks began with one by Rahul Jain.  Frankly, it was another talk on computational complexity and, while interesting, is a topic for which I have a threshold that Jain’s talk exceeded.

Stefano Pironio followed Jain with a really cool discussion on using violations of Bell inequalities to generate random numbers (it included a great Dilbert cartoon in which Dilbert is introduced to a random number generator that is a horned monster that only spits out the number 9, the comment being that one can never really know if it is truly a random occurrence or not).  Anyway, Pironio’s main idea is that violations of Bell inequalities are inherently random events.  The first suggestion that this could be used for cryptography appeared in Roger Colbeck’s PhD thesis and embodies many aspects of no-signalling theorems.  For his Bell estimator, Pironio did not use probabilities.  The result is an expansion of randomness that, in conjunction with Chris Monroe’s group, was used to generate 42 new random bits.

The last talk of the afternoon was on the great paper by the collaboration I’m now calling Flame-broiled Bacon.  Yes, I’m referring to the paper on adiabatic gate teleportation, some of which is discussed here by his co-authorness, The Pontiff (AKA The Bacon).  Mr. Flame-broiled (i.e. Steve Flammia) used some nifty Metallica font to begin the talk, introducing the newly arrived Baby Bacon, named Max (someone in the audience suggested renaming him Min).  Basically, the work Steve spoke about involved creating a spin triplet but in which two of the particles are entangled using a specific Hamiltonian.  This entangled state is then transferred to the third + the middle one (I’m explaining this really badly).  Essentially, the adiabatic evolution teleports the state of one to another.  [Note that somewhere in here Steve made a possibly unintentional reference to the Jackson 5 (ABC, easy as 123) and missed a great opportunity to make a reference to ZZ Top courtesy of ZZ coupling.  Hey, if you want a serious synopsis, go somewhere else.  This blog highlights the hidden gems.]  Their scheme has the advantage of being more robust to errors.  Steve also highlighted an interesting implementation involving turning on and off B-fields in a way that can be used to teleport information., pointing out that this is a bit like a quantum transistor.  The applied field introduces a quantum phase transition that yields a quantum logic gate.  Instead of transferring current as in a transistor, this scheme transfers information!

8 Responses to “QIP – Post 2”

  1. May I suggest you people combine efforts on the same page?

    Etherpad is a real-time shared notebook:

  2. quantummoxie Says:

    What fun would that be? 🙂

  3. Hello. Would most of you consider it significant, if we could recover amplitude information in a case heretofore been considered “lost” from decoherence? (Roughly similar to quantum eraser, but this is after noise.) That certainly would impact quantum cryptography. I propose an experiment that might be able to do that, post of 12/31/09 at the linked website. It’s a draft post, but the idea is reasonably easy to digest. (No illustration yet, but it’s a cascaded double Mach-Zehnder interferometer with phase-scrambling “confuser” in one leg of the first square path.)

  4. quantummoxie Says:


    Unfortunately the link’s not working at the moment. Hmmm… In any case, I would think it would be significant but would want to see the setup. Hopefully that link will fix itself.

    Update: Here is a working link to Neil’s proposal.

  5. OK, I appreciate your interest. I’m working on an image. I had an bitmap already but the blog system didn’t like that. Will try later, maybe this evening. Meanwhile to anyone: the text explains what BS2 output comes out, and recombining that in another BS produces the indicated results.

  6. PS: the dark colors make this blog is hard to use (BTW I have Linux SeaMonkey which is like FireFox/Mozilla/~Netscape.) I have to “pick my own colors” to use the comment box etc. Just FYI.

  7. Hello, I put up an illustration, and a lively discussion is going on. Seriously, I think I’m on to something important. tx

  8. quantummoxie Says:


    Sorry for not responding sooner. This conference has been insanely busy and I haven’t had the time. I have to go check in for my flight now, but I promise to look at it this week sometime. It sounds like a cool idea.

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