Quantum Algorithms
Friday, February 27, 2004
"Intellectual" Conservative on Quantum Theory
From The Intellectual Conservative. The Divinity Case: Imposing Secular Dogmatism: "Today much of what we call 'science' is simply theory. Quantum mechanics, for example, has several different explanations for reality at the subatomic level. Mathematical models are useful, but imperfect, predictors of reality at that level. Quantum mechanics actually 'works' only at the scale of our perceptions, the ordinary world which we observe."

There's a lot wrong with this paragraph, but the last sentence is the most glaring: quantum mechanics does not apply at the scale of our perceptions. As far as the second to last sentence goes: Some quantum level experiments have agreed with theory to some rediculous number of decimal places. The different explanations he refers to are part of philosohpy, not the core of quantum mechanics.
Quantum Relays Using Classical Parts
From Technology Review, quantum repeaters will extend the range of quantum networks, Simple Optics Make Quantum Relay: "The challenge was finding a way to preserve entanglement, which links particle properties like polarization regardless of the distance between the particles....It will be 20 years before the method can be used practically, according to the researchers."
Thursday, February 26, 2004
Note to Feed Aggregator Users
I updated this blog's template to play better with newsfeed aggregation software, but I had to change recent posts individually too, so sorry for the duplicates. For those of you who don't use an RSS/atom aggregator, you should try one. Bloglines is good, with minor problems. NetNewsWire for Mac is supposed to be the best, although I've never tried it, because for some reason I don't use Macs anymore.
Update [26-Feb]: Here is an auto-generated list of feeds I'm subscribed to.
Spin Valve Created
PhysicsWeb - Spintronics goes organic: "Jing Shi and colleagues at the University of Utah in the US have made the first organic 'spin valve' - a device that changes resistance depending on the applied magnetic field. Previous spin valves were made from metals or insulators "
Tuesday, February 24, 2004
Quantum Channel Capacity
From New Journal of Physics: "Channel capacity describes the size of the nearly ideal channels, which can be obtained from many uses of a given channel, using an optimal error correcting code. In this paper we collect and compare minor and major variations in the mathematically precise statements of this idea which have been put forward in the literature."
Monday, February 23, 2004
Knuth's Vacation Photos
Do you ever wonder what geniuses do on vacation? Well for Mr. and Mrs. Donald Knuth, the answer is: take pictures of every diamond shaped road sign you see. It's surprisingly interesting to look at. At least *I* think so.
Church-Turing Thesis vs Quantum Measurement
In this paper, [quant-ph/0402128] Computable Functions, the Church-Turing Thesis and the Quantum Measurement Problem, the authors argue that quantum mechanics cannot break the "Turing barrier." If true, on the one hand, it would be bit disappointing that quantum computers will never do anything truly new (only faster, in some cases. It was already known that qubit-based quantum computers cannot break the "Turing barrier," but quantum mechanics was an open question). On the other hand, it is exciting that the Church-Turing thesis would seem to be not just a statement on the limits of classical computation, but also a limit of physical reality.
Sunday, February 22, 2004
The Best Quantum Computing Resources
I have created a meta-resource for quantum computing newbies. It basically lists some of the best sites/books relating to quantum computing, in my opinion. Instead of being exhaustive, it only lists high quality resources.
New Supernova Findings Bolster Dark Matter
From NY Times, New Data on 2 Doomsday Ideas, Big Rip vs. Big Crunch: "Models which predict wild dark energy densities which change a lot with time don't look so good," Dr. Yun Wang, a cosmologist at the University of Oklahoma, said. "Everybody will go back to the drawing board." Sounds like there's still lots of work to do, but the score over the past few months is: Dark Energy 1, no-Dark Energy 1.
Friday, February 20, 2004
Commerical Quantum Crypto
From SmallTimes, brief summary of recent commercial developments
Decoherence of Matter Waves by Thermal Emission of Radiation Experiment Agrees With Theory
New in Nature (not the free section), Decoherence of matter waves by thermal emission of radiation. From the abstract: "We find good quantitative agreement between our experimental observations and microscopic decoherence theory. Decoherence by emission of thermal radiation is a general mechanism that should be relevant to all macroscopic bodies." A draft is available here.
Update [23-Feb]: Article about this research from SF Chronicle. One person quoted says this is Nobel Prize quality stuff.
Wednesday, February 18, 2004
Feb VJ of Quantum Information
The Feb issue contains the algorithm/computation papers "Simulation of quantum random walks using the interference of a classical field" and "Perturbative formulation and nonadiabatic corrections in adiabatic quantum-computing schemes" along with many others in different subfields.
Monday, February 16, 2004
Google Weirdness
If you search for "quantum algorithm" or "quantum algorithms" right now on google, this blog comes up on about the fifth page or so. The weird thing is, only a week ago, this blog was the #1 hit for both those searches...now it's around #50. Very bizarre that it would fall so far so quickly.
Update [17-Feb]: This website is now completely off google, as far as I can tell. I'm glad I don't make my living from website traffic which would make me dependent on the whims of the google searchbots.
Update [20-Feb]: Google's searchbots "heard" me, so this blog is back on page two at least. Here is a short article, Keeping an Eye on Google, from Technology Review.
Sunday, February 15, 2004
Quantum Atomic Clocks
Very high level overview from science.nasa.gov: Spooky Atomic Clocks
Saturday, February 14, 2004
Another Suspect Press Release
From PRNewswire, ATMOL Inc. to Introduce the Remarkable Breakthrough of Technical Analysis 'J- CHART' at Traders EXPO in New York. "...J-Chart is able to avoid Random-Walk's effects. Furthermore, J- Chart utilizes the Pair Production Phenomenon of Quantum Physics as backbone for its ability of price forecasting."

It's one thing to use computing buzzwords to promote a product, but throwing in quantum physics appears disingenuous in this example. Perhaps they are using some mathematical formalism that has some strong resemblance to pair production in quantum mechanical equations, but that does not justify the above quote. It would be like someone having F = m*a; in their source code and claiming they use the power of Newtonian Mechanics in their software. Meaningless at best, misleading at worst.
Faster Than Light Inter-Galactic Email
From NewsFactor Network - Quantum ComSat May Send Mail Faster Than Light Speed: "The use of entangled photons for quantum cryptography was shown experimentally by different groups for long distances using optical fibers," University of Geneva physicist Ivan Marcikic told NewsFactor. "By using satellites, this distance becomes several orders of magnitude longer. It is thus a new approach to increase the distance between two entangled photons."

You also need a non-faster than light classical communication channel in order to correctly interpret the results of the measurements...but maybe I'm missing something. This looks like the relevant paper. There's nothing in there about faster than light infomation travel, although it does have an interesting discussion of transmitting entangled qubits via satellites. The overhyping/lack of understanding by newsfactor isn't doing anybody any good.
Tuesday, February 10, 2004
Electricity Teleportation
From Technology Review: Electricity Teleportation Devised: "The method could eventually be used to instantly transport information between the quantum bits, or qubits, of a quantum computer if electrons could be transported over distances of around 100 microns."
Update [15-Feb]: Another article on the topic here, from Physical Review Focus.
Securing eVoting with Quantum Cryptography
From this Newswire Canada press release, via Cryptonomicon.Net: Swiss companies will use "this technology [...] to reinforce the security of E-Voting applications through tamper and eavesdropping detection via a Quantum Channel connecting the central Government's servers with local county servers."
New Issue VJ of Quantum Information
Better late than never, Virtual Journal of Quantum Information--January 2004 came out today. It features a paper entitled "Quantum information and relativity theory" along with 8 algorithm and computation articles, including "Universal quantum interfaces".
Monday, February 09, 2004
Stroustrup's Foundations class at Texas A&M
I'm sure just about every physicist wishes they could go back in time and sit in on the famous Feynman lectures during the 60's. Well right now, a lucky group of beginning engineering students are learning basic computer science from Dr Bjarne Stroustrup. There probably won't be a book series in 40 years to commemorate these lectures, but you can see the course website here: ENGR 112 - Foundations of Engineering II (B)
Saturday, February 07, 2004
A New Kind of Science Online
David Appell of Quark Soup points out here, "Stephen Wolfram's much discussed book A New Kind of Science is now freely available online."
Update [24-Feb]: There is a good review of the book here by Scott Aaronson, which concentrates on computational complexity and quantum physics related aspects.
Quantum Weight Loss
I often get disappointed at scientists in various disciplines for not being more vocal when their field gets trampled through the media and the public gets a serious dose of mis-information. Well guess what, according to FemOne, their new "Lean Choices(TM) Weight Loss System" uses the "fascinating technology of quantum physics into a system that is simple and easy to live with." Wow really? I checked out their website, and I couldn't find much on this "quantum physics technology" they use, the best I could find was this here:

"Backed by quantum physics and thanks to cutting-edge technology, [Bio-Lean Energy Buttons] harmonize your body’s response to external stressors that bombard us everyday. Recent studies indicate that stress can negatively impact the body’s ability to absorb vital nutrients, which in turn leads to the inability to lose unwanted weight and is a contributing factor in stress related illness. There is also further proof that electromagnetic fields (EMFs) from cell phones, computers and other electronic devices stimulate stress responses in our bodies. Bio-Lean Energy Buttons are programmed to a “healthy frequency” and literally “harmonize” how EMFs affect the body."

More stuff here:

"This relates to research in quantum physics that proves that if external stressors are “neutralized,” or reduced, your body’s cells will resonate and “respond in harmony” to nutritional and lifestyle factors in a healthier way...."

No one has a copyright on quantum physics, so anyone can say anything they want about it. But that doesn't mean the quantum physics community should just sit back quietly as they do so. FemOne doesn't say enough about their product's use of quantum physics for me to say that they are explicitly misrepresenting their product, but I would definitely like to see some legitimate research backing up their claims.
Wednesday, February 04, 2004
Bush budget: $16.2 million for quantum computing and communications
Out of the $60 billion of proposed for "IT spending" in the 2005 US budget, a full 0.027% is earmarked for "quantum-level computing and communications systems and other projects."
Tuesday, February 03, 2004
Galaxy Clusters and Dark Energy
I don't have much evidence on my side, but I've long been a bit suspicious about the existence of dark energy. This recent development, upon much more analysis, could spell the beginning of the end for dark energy: Universe Today - Are Galaxy Clusters Corrupting Our View of the Big Bang?
Update [07-Feb]: Physics Web's take on this, which includes link to the original paper, which was originally published June 2003, and updated in Jan 2004.
Update [09-Feb]: Economist weighs in too

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