Category: Computer Science

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Back To Tech, Back to Unreality

I’m at SQuint 2007 which is being held on the campus of Caltech this year. Quite a turnout this year: something like 150 people attending! In fine Caltech tradition the night of my arrival I got pretty much no sleep. And I keep getting the feeling that I have a homework due somewhere on campus.
Cool work by Patricia Lee at NIST:

Abstract. We report on the experimental demonstration of radio frequency addressing of atoms in every other site of a double-well optical lattice, independent of their nearest neighbors at a distance of less than an optical wavelength. By dynamically controlling the lattice and the vector light shifts, the atoms’s spatial and spin degrees of freedom are entangled in each double well. We have also observed a coherent spin-exchange interaction between pairs of atoms in the double-well lattice, which can be used as a mechanism for a square-root-of-swap gate.

During the talks on quantum error correction, it was mentioned that in the very cool threshold paper of Aliferis, Gottesman, and Preskill (quant-ph/0504218), they call the inductive proof of the threshold theorem for fault-tolerance the “threshold dance.” This, of course, brings up the interesting question of what the dance moves are in this dance and the even more important question which is should this dance be part of my upcoming wedding?

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For 100 Billion I Could Do It, I Think

From a Boston Herald article (appears to be an AP news release):

“Users don’t care about quantum computing – users care about application acceleration. That’s our thrust,” he said. “A general purpose quantum computer is a waste of time. You could spend hundreds of billions of dollars on it” and not create a working computer.

And you’re probably happy that you don’t have an account on fool.com or else you might read this article comparing the demonstration to December 17, 1903.

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QEC07

A new conference: the First International Conference on Quantum Error Correction. QEC07 website here. Dec 17-21, 2007:

Quantum error correction of decoherence and faulty control operations forms the backbone of all of quantum information processing. In spite of remarkable progress on this front ever since the discovery of quantum error correcting codes a decade ago, there remain important open problems in both theory and applications to real physical systems. In short, a theory of quantum error correction that is at the same time comprehensive and realistically applicable has not yet been discovered. Therefore the subject remains a very active area of research with a continuing stream of progress and breakthroughs.
The First International Conference on Quantum Error Correction will bring together a wide group of experts to discuss all aspects of decoherence control and fault tolerance. The subject is at this point in time of a mostly theoretical nature, but the conference will include talks surveying the latest experimental progress, and will seek to promote an interaction between theoreticians and experimentalists.
Topics of interest include, in random order: fault tolerance and thresholds, pulse control methods (dynamical decoupling), hybrid methods, applications to cryptography, decoherence-free subspaces and noiseless subsystems, operator quantum error correction, advanced codes (convolutional codes, catalytic, entanglement assisted, …), topological codes, fault tolerance in the cluster model, fault tolerance in linear optics QC, fault tolerance in condensed matter systems, unification of error correction paradigms, self-correcting systems, error correction/avoidance via energy gaps, error correction in adiabatic QC, composite pulses, continuous-time QEC, error correction for specific errors (e.g., spontaneous emission), etc.

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D-wave In D-news

Lots of blogging and press picking up on D-wave and Orion so I thought I’d collect a few here. The offical press release is here. I’d love to hear from anyone who has attended.
Scott Aaronson called me a Chinese restraraunt placemat in his The Orion Quantum Computer Anti-Hype FAQ (Update (3:17pm 2/13/07): Scott’s post now contains an update by the great Lawrence Ip, who now works for Google.) Doug Natelson, who gave an excellent talk here at UW a few weeks ago, poses three questions about the D-wave demo. Peter Rhode is every bit the skeptic and beats out Doug Natelson with four points. Ars-technica’s Chris Lee takes a shot at explaining adiabatic quantum computation and uses the word deathmatch here. You can find a bad quantum computing joke at the end of this blog post. I find this post amusing, if for nothing more than bringing politics into quantum computing. Coherence* remains the prettiest quantum computing website and has a choice Seth Lloyd comment “I’ll be a bit of a skeptic until I see what they have done. I’m happy these guys are doing it. But the proof of the pudding is in the eating.”
More mainstreamish media produces some truely incredible hype. One of my favorites is at physorg.com where we find the title a “New supercomputer to be unveiled” along with the choice gibberish “A Canadian firm is claiming to have taken a quantum leap in technology by producing a computer that can perform 64,000 calculations at once.” I flipped a coin 16 times today, can I get some venture capital? 🙂 Personally I like Gizmodo’s title: “D-Wave Quantum Computer to Span Multiple Universes Next Tuesday?” They also use the word sugerdaddy. If you want more reasons to be angry about hype or at bad journalism, go over to a wired gadget blog where you’ll find

There are certain classes of problems that can’t be solved with digital computers,” said Herb Martin, the firm’s CEO, over a decidedly-noisy digital cell phone. “Digital computers are good at running programs; quantum computers are good at handling massive sets of variables.”

Turing is certainly turning in his grave over that first sentence and, since Peter Shor is alive and well, I wonder if he is spinning today?
And don’t even get me started on this EETimes article. Choice:

Nondeterministic polynomial (NP) problems are the most difficult to solve on conventional computers because each variable adds yet another dimension to its possible solutions.

No, no, no! So many no’s I can’t even write it down. First of all NP problems include problems in P, so they definitely aren’t the most difficult to solve on a conventional computer. Second, the essentence of NP-complete problems is NOT just that you have an exponential search space. You’d think a Electrical Engineering rag would have taken some computer science courses? Then, of course EETimes only digs their grave deeper:

Quantum computers, on the other hand, can evaluate all possible solutions simultaneously and find the optimal solution, often in just a few clock cycles, thereby not only vastly speeding up the time taken to find the solution but also finding the most optimal result.

Okay, at that point I’ll admit I had to stop reading cus my brain was about to explode.
Oh, and whatever you do, don’t search for “first quantum computer” if you’ve ever performed a quantum computing experiment (that includes a lot of MIT Physics majors? Ack, is NMR quantum computation really quantum computation?) You might get a little miffed at all the years you spent in grad school doing what you thought were small quantum computer experiments.

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One Link, Many Link, Social Link

Just back from an awesome lecture by Raghu Ramakrishnan (Yahoo Research/U Wisconsin) entitled “Community Systems: The World Online.” Wow. The talk should be online here soon. In my head I’ve always kind of associated social websites like flicker, youtube, etc as “stuff for fun” so to speak. But Raghu makes a strong case, I think that these sorts of websites are actually the manner in which make the next step towards improving the responsiveness of the web. Okay so maybe that wasn’t his main point, but I’d like to argue that this idea was a valid conclusion to draw from his talk. Indeed, some might even claim that the new boom (Are we at the beginning? Hop on quick youngsters!) in websites with a “social” aspect (by which I mean all sites which have a community aspect, not just those with a “social” component) is all about the increased usefulness of exploiting the community link networks for increased functionality on using the web. It is almost like, as Google moved beyond Altavista (and others) use of one link in anchor text to many links, these social sites are experience a similar revolution in the mining of the community information links beyond the simple one link stage.

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Quantum Engineering Sounds Fun

I missed this last year, but Yale has established a Institute for Nanoscience and Quantum Engineering. Who will be the first to file out a tax for with “Occupation: Quantum Engineer?”
Update: Oh, and I missed this one too. The University of Maryland, NIST, and the NSA have established the Joint Quantum Institute under the direction of Christopher J. Lobb and Carl J. Williams. It will be hard for west coast types to avoid jokes about what they are smoking at this institute, won’t it? 🙂

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Talk Next Week

For local Seattlites the following shameless self promotion message 🙂 Next Tuesday at 4pm I’m giving a talk in the Physics department (C421 Physics/Astronomy Building) for the Condensed Matter and Atomic (CMA) Physics Seminar. The title of the talk is “When Physics and Computer Science Collide: A Cross Cultural Extravaganza” and the abstract is

In 1994 Peter Shor discovered that computers operating according to quantum principles could efficiently factor integers and hence break many modern cryptosystems. Since this time researchers from disciplines–physics, computer science, chemistry, and mathematics–have been engaged in building an entirely new discipline now known as quantum information science. Being a highly interdisciplinary endeavor, quantum information science requires not just mastery of physics or of computer science, but an ability to take insights from both fields across the cultural divide. In this talk I will discuss how physicists can contribute to the computer science side of quantum computing and how computer scientists can contribute to the physics side of quantum computing via a series of vignettes taken from research in my group here at UW.