O brave new quantum world!
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.
Hoisted from DaOptimizer’s comments, YouTube videos of d-wave’s announcement. Also, Lieven Vandersypen (who factored 15, which sounds simple, but if you think the factoring experiment done on IBM’s NMR machine was simple, then you haven’t seen their pulse sequence!) weighs in on D-wave here.
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.
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.
A reader points me to physics/0702069: “Would Bohr be born if Bohm were born before Born?” by H. Nikolic. My head hurts just reading that title.
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? 🙂
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.
Am I reading this correctly? Is it really nearly 5000 euros to buy this report on quantum cryptography?
Congrats to Gilles Brassard for being one of three Herzberg award finalist. The winner will be announced on March 19 and will get $1 million in extra research funds. (Herzberg, for those who don’t know, won the Nobel Prize in Chemistry…I have many fond memories of Herzberg’s books (i.e. Molecular Spectra and Molecular Structure: Spectra of Diatomic Molecules 
Well it’s been two weeks and I have had absolutely zero time to think about scirate. (It was midterm week!) So far 71 users have registered. Whoop! I have certainly slowed down the progress of science (what do you think this blog and scirate.com is for, after all?) So what were the highest scited papers in the time preiod Jan 23-Feb 6?
7 votes: quant-ph/0701173 [abs] Quantum walks on quotient graphs by Hari Krovi and Todd A. Brun
7 votes: quant-ph/0702031 [abs] A scheme for demonstration of fractional statistics of anyons in an exactly solvable model by Y.J. Han, R. Raussendorf, and L. M. Duan.
6 votes: quant-ph/0701165 [abs] A precise CNOT gate in the presence of large fabrication induced variations of the exchange interaction strength by M. J. Testolin, C. D. Hill, C. J. Wellard and L. C. L. Hollenberg
6 votes: quant-ph/0702020 [abs] How much of one-way computation is just thermodynamics? by Janet Anders, Damian Markham, Vlatko Vedral and Michal Hajdusek
5 votes: quant-ph/0701149 [abs], quant-ph/0702008 [abs]
The first papers with 7 votes, quant-ph/0701173, explores the role symmetries of a graph play in (discrete) quantum random walks on theses graphs. Of course whenever a physicist sees the word “symmetries” the immediate reaction should be “change basis”! Indeed for a proper choice of coin in the quantum random walk, the symmetries of the graph (the group of automorphisms) can be inherited by the unitary operator discribing the evolution of the quantum random walk. Whenever you have a unitary operator which is symmetric under a representation of a group, then, via Schur’s lemma, you know that this unitary operator will have a very nice form. Indeed if you decompose the representation into its irreducible irreps, then the unitary operator can only have support over the space of degeneracies of a given irreducible irrep. So, for the quantum random walks, this means that the walk will be confined to a particular subspace. In the setup considered in the paper this works out to be a walk on the quotient graph obtained from the original graph and some subgroup of the automorphism group. Very fun stuff. The authors then go on to analyze hitting times, worry mostly about the case of inifinite hitting times. They develop a criteria for spotting when the walk on the quotient time is not infinite (building on some prior work.) Okay, so what’s the next step? At what point can you identify when the walk will have fast hitting times would be nice. Also can you use the above arguments to spot when classical walks will be exponentially slower?
The second paper with 7 votes, quant-ph/0702031 is four pages, so it must be going to PRL 😉 The basic idea of this paper is fairly straightforward. The authors point out that it is easy to think about generating the ground state of Kitaev’s toric code using methods within experimental reach in ion traps and in optical lattices. This prepared state can then be used to “demonstrate” anyon statistics. In other words, instead of preparing a state in Kitaev’s toric code by cooling to the (degenerate) ground state, one can just prepare such a ground state using a simple quantum circuit, perform the braiding operations, and observe the effects of the (abelian) anyon statistics. Okay, so let me play the devil’s advocate here (something I don’t do well since I’m a coward.) Should we really claim that this is would constitute a “demonstration of fractional statistics of anyons”? My worry here is with the word “anyon” which, it seems, we usually restrict to things which are quasiparticle excitations. Of course this may just be a matter of taste, but I’d be curious to hear what others think. On a less subjective, and more concrete point, one interesting issue which was not addressed in the paper (at least on my admittedly fast first reading) was how errors will propogate in the scheme described for preparing the Kitaev state. Is it true that the preparation is in any way fault-tolerant? For example if you’re doing this in ions is it really possible with current two gate fidelities to demonstrate this in the 6 qubit setting? Interestnig stuff! How long before one of the experimental groups gets to exclaim “fractional statistics” after performing a few thousand experiments 🙂 ?
Okay, enough Scirate pimping. Let’s see what the next round of papers bring (how long before ideas hatched at QIP hit the presses? 🙂 )