Thursday, September 24, 2009
Sunday, September 20, 2009
Researchers have devised a penny-sized silicon chip that uses photons to run Shor's algorithm - a well-known quantum approach - to solve a maths problem.
The algorithm computes the two numbers that multiply together to form a given figure, and has until now required laboratory-sized optical computers.
This kind of factoring is the basis for a wide variety of encryption schemes.
The work, reported in Science, is rudimentary but could easily be scaled up to handle more complex computing.
Shor's algorithm and the factoring of large numbers has been a particular case used to illustrate the power of quantum computing.
Quantum computers exploit the counterintuitive fact that photons or trapped atoms can exist in multiple states or "superpositions" at the same time.
For certain types of calculations, that "quantum indeterminacy" gives quantum computers a significant edge.
While traditional or "classical" computers find factoring large numbers impracticably time-consuming, for example, quantum computers can in principle crack the problem with ease.
That has important implications for encryption methods based on factoring, such as the "RSA" method that is used to make transactions on the internet more secure.
Optical computing has been touted as a potential future for information processing, by using packets of light instead of electrons as the information carrier.
But these packets, called photons, are also endowed with the indeterminate properties that make them quantum objects - so an optical computer can also be a quantum computer.
In fact just this kind of photon-based quantum factoring has been accomplished before, but the ability to put the heart of the machine on a standard chip is promising for future applications of the idea.
"The way people used to make this kind of circuit consumed square metres of laboratory space and took graduate students many months to align," said Jeremy O'Brien, the University of Bristol researcher who led the work.
"Doubling the complexity of the circuit often times turns it from being a difficult task to a practically impossible one, whereas for us to double the complexity it's really straightforward," he told BBC News.
The Bristol team's approach makes use of waveguides - channels etched into the chips that provide a path for the photons around the chips like the minuscule wires in conventional electronics.
While Professor O'Brien said he is confident that such waveguides are the logical choice for future optical quantum computers, he added that there is still a significant amount of work to do before they make it out of the laboratory.
The prototype version, finds the factors of 15 - three and five - a task that the team concedes could be easily accomplished by a child.
"To get a useful computer it needs to be probably a million times more complex, so a full-scale useful factoring machine is still at least two decades away," he said.
"But this is one important step in that direction."
Saturday, September 19, 2009
Augmented Reality in a Contact Lens
A new generation of contact lenses built with very small circuits and LEDs promises bionic eyesight
Image: Raygun Studio
BY BABAK A. PARVIZ // SEPTEMBER 2009
The human eye is a perceptual powerhouse. It can see millions of colors, adjust easily to shifting light conditions, and transmit information to the brain at a rate exceeding that of a high-speed Internet connection.
But why stop there?
In the Terminator movies, Arnold Schwarzenegger’s character sees the world with data superimposed on his visual field—virtual captions that enhance the cyborg’s scan of a scene. In stories by the science fiction author Vernor Vinge, characters rely on electronic contact lenses, rather than smartphones or brain implants, for seamless access to information that appears right before their eyes.
These visions (if I may) might seem far-fetched, but a contact lens with simple built-in electronics is already within reach; in fact, my students and I are already producing such devices in small numbers in my laboratory at the University of Washington, in Seattle [see sidebar, "A Twinkle in the Eye"]. These lenses don’t give us the vision of an eagle or the benefit of running subtitles on our surroundings yet. But we have built a lens with one LED, which we’ve powered wirelessly with RF. What we’ve done so far barely hints at what will soon be possible with this technology.
Conventional contact lenses are polymers formed in specific shapes to correct faulty vision. To turn such a lens into a functional system, we integrate control circuits, communication circuits, and miniature antennas into the lens using custom-built optoelectronic components. Those components will eventually include hundreds of LEDs, which will form images in front of the eye, such as words, charts, and photographs. Much of the hardware is semitransparent so that wearers can navigate their surroundings without crashing into them or becoming disoriented. In all likelihood, a separate, portable device will relay displayable information to the lens’s control circuit, which will operate the optoelectronics in the lens.
These lenses don’t need to be very complex to be useful. Even a lens with a single pixel could aid people with impaired hearing or be incorporated as an indicator into computer games. With more colors and resolution, the repertoire could be expanded to include displaying text, translating speech into captions in real time, or offering visual cues from a navigation system. With basic image processing and Internet access, a contact-lens display could unlock whole new worlds of visual information, unfettered by the constraints of a physical display.
Besides visual enhancement, noninvasive monitoring of the wearer’s biomarkers and health indicators could be a huge future market. We’ve built several simple sensors that can detect the concentration of a molecule, such as glucose. Sensors built onto lenses would let diabetic wearers keep tabs on blood-sugar levels without needing to prick a finger. The glucose detectors we’re evaluating now are a mere glimmer of what will be possible in the next 5 to 10 years. Contact lenses are worn daily by more than a hundred million people, and they are one of the only disposable, mass-market products that remain in contact, through fluids, with the interior of the body for an extended period of time. When you get a blood test, your doctor is probably measuring many of the same biomarkers that are found in the live cells on the surface of your eye—and in concentrations that correlate closely with the levels in your bloodstream. An appropriately configured contact lens could monitor cholesterol, sodium, and potassium levels, to name a few potential targets. Coupled with a wireless data transmitter, the lens could relay information to medics or nurses instantly, without needles or laboratory chemistry, and with a much lower chance of mix-ups.
Three fundamental challenges stand in the way of building a multipurpose contact lens. First, the processes for making many of the lens’s parts and subsystems are incompatible with one another and with the fragile polymer of the lens. To get around this problem, my colleagues and I make all our devices from scratch. To fabricate the components for silicon circuits and LEDs, we use high temperatures and corrosive chemicals, which means we can’t manufacture them directly onto a lens. That leads to the second challenge, which is that all the key components of the lens need to be miniaturized and integrated onto about 1.5 square centimeters of a flexible, transparent polymer. We haven’t fully solved that problem yet, but we have so far developed our own specialized assembly process, which enables us to integrate several different kinds of components onto a lens. Last but not least, the whole contraption needs to be completely safe for the eye. Take an LED, for example. Most red LEDs are made of aluminum gallium arsenide, which is toxic. So before an LED can go into the eye, it must be enveloped in a biocompatible substance.
Racetrack Memory: The Future Third Dimension of Data StorageA device that slides magnetic bits back and forth along nanowire 'racetracks' could pack data in a three-dimensional microchip and may replace nearly all forms of conventional data storage.
A device that slides magnetic bits back and forth along nanowire "racetracks" could pack data in a three-dimensional microchip and may replace nearly all forms of conventional data storage
More from the Magazine
The world today is very different from that of just a decade ago, thanks to our ability to readily access enormous quantities of information. Tools that we take for granted—social networks, Internet search engines, online maps with point-to-point directions, and online libraries of songs, movies, books and photographs—were unavailable just a few years ago. We owe the arrival of this information age to the rapid development of remarkable technologies in high-speed communications , data processing and—perhaps most important of all but least appreciated—digital data storage.
Each type of data storage has its Achilles’ heel, however, which is why computers use several types for different purposes. Most digital data today, such as the information that makes up the Internet, resides in vast farms of magnetic hard disk drives (HDDs) and in the HDDs of individual computers. Yet these drives, with their rotating disks and moving read/write heads, are unreliable and slow. Loss of data because of so-called head crashes occurs relatively often. Regarding speed, it can take up to 10 milliseconds to read the first bit of some requested data. In computers, 10 milliseconds is an eon—a modern processor can perform 20 million operations in that time.
POSTED BY: DEXTER JOHNSON // FRI, SEPTEMBER 18, 2009
I saw this catchy headline over at Scientific American: Tree Electricity Runs Nano-Gadget. Apparently the headline was inspired by research reported in the IEEE’s Transactions on Nanotechnology by researchers from the University of Washington in Seattle who discovered they could derive enough electricity from a maple tree to run a device, as long as that device had dimensions of 130 nanometers.
Now I get why a science publication would pick this up as a cute little story to entertain its readers and even its listeners (it is accompanied with a podcast), but I am trying to figure out if there is any larger goal aimed at by the researchers. I admittedly could not locate the experiment on the IEEE Transactions on Nanotechnology website to determine what the greater purpose was.
But I have been thinking that if you were able to hook up all the trees in the state of Washington into one macroscale device you might be able to power something like an iPod for an hour or so. Might make for an interesting experiment.
Friday, September 18, 2009
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Sunday, September 13, 2009
Try double-clicking directly on:
/Applications/eclipse/Eclipse.app/Contents/MacOS/eclipseHint: You may have to right-click on Eclipse.app and select "Show package contents."
If that doesn't work, check in:
/Applications/eclipse/Eclipse.app/Contents/MacOSfor a file named eclipse.ini
Check the file for file names or paths that no longer exist and change/delete them.
Thursday, September 3, 2009
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