quantum computing
pontiff | March 31, 2008Normally when I think about quantum computers, I think about systems which are pretty cold, since a thermal equilibrium state at high temperature is a very mixed state. But is it really true that a quantum computer needs to be cold to quantum compute? I've often wondered (some would say pontificated) about this, and so I was excited when I found this Physical Review Letter describing quantum computing using plasmas.
The idea of this new approach, according to the paper, is to use modes in the Debye sheath as qubits. Because of the Child-Langmuir law, the current in this sheath is quantized…
pontiff | March 31, 2008Postdoc in Italy, AQIS 2008 Call for Papers, the Register reports on QUEST, and the New Scientist morphs into the No Scientist.
There is a postdoc position available in Italy:
A Post Doctoral fellowship in Quantum Information Theory is available at the University of Camerino, Department of Physics, associated with the EU project "Correlated Noise Errors in Quantum Information Processing" (CORNER FP7-ICT-2007).
The research work consists in the development of optimal encoding and decoding procedures for quantum memory channels. This should be done in connection with the channels…
pontiff | March 28, 2008Linear optics quantum computing, where one combines linear optics with the nonlinear processes of single photon creation and single photon detection, is a relative newcomer onto the scene of possible routes toward quantum computing. Whenever I think about these schemes, what jumps into my head is a crazily filled optical bench, like the one below from the Zeilinger group:
Now, I'm but a mere theorist, but I think even theorists like me understand that trying to build a large scale version of this scheme, which has considerable overhead behind it in terms of the number of modes needed, is a…
pontiff | March 27, 2008It looks like DARPA is getting back into funding academic research in quantum computing. Here is a new BAA for a program called QuEST. And it looks like they want revolution, not evolution:
DARPA is soliciting innovative research proposals in the area of Quantum Entanglement Science and Technology (QuEST). Proposed research should investigate innovative approaches that enable revolutionary advances in the fundamental understanding of quantum information science related to "small" quantum systems. Specifically excluded is research which primarily results in incremental improvement to the…
pontiff | March 24, 2008Over at Emergent Chaos I found an article which throws down the gauntlet over quantum computers. And there isn't anything I cherish more than gauntlets thrown down!
Note: I should preface this by saying that I don't consider myself a over the top hyper of quantum computers in the sense attacked by the author. I find quantum computers fascinating, would really like to see if one can be built, but find the hyperbole that accompanies any small advance in the field a bit over the top. However I also think the article misses a lot of important points (and insinuates that people haven't…
pontiff | March 15, 2008As noted by Lance, the new journal ACM Transactions on Computation Theory is now accepting papers. Note for quantum computing theorists:
ACM Transactions on Computation Theory will cover theoretical computer science complementing the scope of the ACM Transactions on Algorithms and the ACM Transactions on Computational Logic including, but not limited to, computational complexity, foundations of cryptography, randomness in computing, coding theory, models of computation including parallel, distributed and quantum and other emerging models, computational learning theory, theoretical computer…
pontiff | March 12, 2008How cut-throat is arXiv:0803.0272? This cut-throat (taken from v2 of the paper):
X. CONCLUSION AND FURTHER READING
This section will be completed when our error correction simulations have generated more data.
Reminds me of my idea to write a paper and submit it to the arxiv entitled "An Efficient Quantum Algorithm for the Graph Isomorphism Problem." Sure, version 1, won't have the algorithm, but hey, why should I make you wait?
pontiff | March 7, 2008Hurray! My letter to Physics Today along with a delightful response from N. David Mermin has been published. I particularly enjoyed Mermin's closing line:
It may be quixotic (but certainly not Qxotic) to try to correct the spelling of an entire community, but I owe it my best shot. What else is retirement good for?
Sweet! Now I can check off from my list of things to do in life: "Get published in Physics Today over issues related to my literature degree."
pontiff | March 3, 2008Over at Information Processing, the InfoProcessor talks about teaching Bell's theorem:
I find that the hardest thing about teaching this material in class is that, after half a year of training students' brains to think quantum mechanically, it is extremely difficult to get them to feel the weirdness of Bell's theorem and spooky action. It all seems quite normal to them in the context of the course -- they know how to calculate, and that's just how quantum mechanics works!
In the comments an anonymous commenter says that this is all backward, that Bell's theorem isn't strange, and that we…
pontiff | February 21, 2008QCMC 2008 in Calgary call for abstracts, Quantum Information and Control in Cairns, Australia call for abstracts, Covaqial, Brassard nominated for Herzberg Medal, and the limits of quantum computers.
QCMC 2008, to be held in Calgary (why do I want to say "yippee ki yay" whenever I hear the word "Calgary?") is asking for abstract submissions:
This is a call for abstract submission to the Ninth International Conference on Quantum Communication, Measurement and Computing (QCMC), which will be held at the University of Calgary, Canada, on August 19 to 24, 2008.
A one-page abstract of your…
pontiff | February 19, 2008There are days when I wish quantum cryptography was a mature, installed, technology. Today is one of those days. Why? You might think its because I'm a quantum obsessed physicist whose daily sustenance depends on the future of quantum information science. But no. Today I wish quantum cryptography were installed because today the Supreme Court rejected a challenge to the Bush administration's domestic spying program;
The Supreme Court rejected a challenge Tuesday to the Bush administration's domestic spying program.
The justices' decision, issued without comment, is the latest setback to…
pontiff | February 16, 2008Yes we work on Saturdays. Okay work may be the wrong word. Updated as the day goes along and my brain doesn't fill up (plus I'm chairing a session, so is it ethical to chair and blog at the same time?)
The first talk of the morning was by Edward Farhi. Farhi talked about the NAND tree algorithm (see the Optimizer along with quant-ph/0702144 and its plethora of follow up works.) This was only the second computer talk Farhi has given. That's right, hell has frozen over, and MIT physic professors have given up transparencies and are now using computers. I feel like an era has come to pass…
pontiff | February 15, 2008Sloan awards have been announced for this year. On the list I noticed at least two three quantum computing/information related names: Alexandre Blais (University of Sherbrooke), Andris Ambainis (University of Waterloo), and Jason Petta (Princeton.) Congrats!
pontiff | February 15, 2008Jeff Kimble, who taught me all about waves as a second year undergraduate at Caltech, is interviewed by Scientific American.
My favorite part:
Switching gears--this new movie, Jumper, is about a kid, and some other people, who teleport from place to place.
I didn't know that.
If you saw X-Men, with Nightcrawler...
I haven't seen X-Men either.
Do you watch Heroes on NBC?
No. I watch some of the football playoffs.
But you know Captain Kirk...
I have some advice. Just don't talk about teleporting people in your story. The technical base of our society is information commerce, and in the next 20…
pontiff | February 15, 2008Live blogging from day one of the talks at SquInT 2008. Updated as the day goes along. So hit that refresh button :)
In a sign that history may be warping itself into a cirlce, the first speaker of the day was Serge Haroche, who was the first speaker at the first SqUinT conference ten years ago. Close time like curves anyone?
Haroche talked about quantum nondemolition measurements of a photon number in a cavity (see 0707.3880.) A quantum nondemolition measurement is a measurement of eigenstates which commutes with the free evolution of the quantum system (thus only external interactions…
pontiff | February 14, 2008I've never live blogged before (well I've been alive while I've blogged, but that is different, I guess), but maybe it will make me pay more attention to the talks, so here goes nothing. Oh, and happy Hallmark(TM) Valentines day! I'll be updating these posts as the conference goes along.
John Martinis led a tutorial on measuring coherence in one qubit (Rabi flopping, Ramnsey interference, lifetimes, spin echo), measuring fidelities of one qubit gates, and process tomography for one and two qubit systems. All illustrated with beautiful experimental data from his group at UCSB.
Most…
pontiff | February 13, 2008Yep, lucky me I'm off to Santa Fe tomorrow morning for the tenth annual SquInT conference. Holy moly ten years of SqUiNT conferences really makes me feel old. I wonder how many Chiles I've eaten over all of those conferences (and I don't even want to think about how many Margaritas or quantum beers I've had.)
For fun, and because I'm procrastinating and because I'm self-centered, I decided to go back and look at how I'd participated in this conference:
SqUiNT I (1999): Poster: "Concatenating decoherence free subspaces with quantum error correcting codes"
SqUinT II (2000): Talk: Quantum…
pontiff | February 12, 2008Via the Computational Complexity (welcome back Lance), the list of accepted papers for CCC 2008 has been posted. Woot, that's a lot of quantum inspired papers. By my count 7 of 33. Quoteth Feynman
...and I'm not happy with all the analyses that go with just the classical theory, because nature isn't classical, dammit, and if you want to make a simulation of nature, you'd better make it quantum mechanical...
pontiff | February 8, 2008New results out of the Martinis lab at UCSB have shown single qubit gate fidelities of 0.98 for a superconducting phase qubit. This is significantly better than previous single qubit gate fidelities in their system and in any other superconducting qubit system. It is an extremely impressive number. (Seems that carefully crafted microwaves pulses were a big help in getting the gate fidelity to this level.) Martinis is speaking at SQUINT 2008, but just in a tutorial section. Maybe we will get lucky and a bit of these new fidelities will leak into his talk.
pontiff | February 7, 2008Two faculty postions in experimental Quantum Information and Nanoscience are being advertised at the University of Bristol. The positions are a part of the Centre (not sure what that word is) for Quantum Photonics and will be housed in the new £11M Nanoscience & Quantum Information Building. Since quantum and nano are so small they should be able to cram a lot of work in this new building! Oh wait, that's not how it works.
The listing:
The University of Bristol is seeking to make two academic (faculty) appointments jointly in the Department of Physics and Department of Electrical…