Posted by Benjamin Roudenis on December 23, 2009 0 comments
By dipping an ordinary piece of paper into ink infused with carbon nanotubes and silver nanowires, scientists have been able to create a low-cost battery or supercapacitor that is ultra-lightweight, bendable and very durable. The paper can be crumpled, folded or even soaked in acidic or basic solutions and still will work.
Stanford University scientist Yi Cui had previously created nanomaterial energy storage devices using plastics, but his new research showed that a paper battery is more durable because the ink adheres more strongly to paper. Coating a sheet of paper with ink made of carbon nanotubes and silver nanowires produced a highly conductive storage device that could be used in a multitude of applications.
“These nanomaterials are special,” Cui said. “They’re a one-dimensional structure with very small diameters. “The small diameter helps the nanomaterial ink stick strongly to the fibrous paper, making the battery and supercapacitor very durable. The paper supercapacitor may last through 40,000 charge-discharge cycles – at least an order of magnitude more than lithium batteries. The nanomaterials also make ideal conductors because they move electricity along much more efficiently than ordinary conductors, Cui said.
The flexibility of paper allows for many clever applications. “If I want to paint my wall with a conducting energy storage device,” Cui said, “I can use a brush.” In his lab, he demonstrated the battery by connecting it to an LED (light-emitting diode), which glowed brightly.
Posted by Benjamin Roudenis on December 22, 2009 0 comments
Researchers knew that the information carried in light pulses could be transferred to clouds of ultracold atoms, called Bose-Einstein condensates. In this technique, a laser called a control laser prepares the atomic cloud for an incoming light beam. As the photons fly in, they leave an imprint in a subset of the atoms. This imprint, stored in a quantum property known as spin, contains all the relevant information needed to reconstitute the light beam. But the imprint is fragile and deteriorates in milliseconds. The light’s information is lost as other atoms in the cloud interfere with the imprint.
Lene Hau of Harvard University and colleagues overcame this problem by sequestering the matter imprint from the rest of the atoms in the cloud. The team shone a pulse of laser light — which looks like the yellow light from street lamps, Hau says — into a small cloud of sodium atoms. A three-microsecond pulse produced a stretch of light about a kilometer long, but as the pulse entered the atom cloud, it began to compress. Like an accordion closing, the light folded up and crammed itself into a space just 0.02 millimeters long. The spin states of the sodium atoms in the light’s path were changed, forming the matter imprint. By turning off the control laser, the researchers were able to freeze the matter imprint.
Next, the researchers strengthened the magnetic field applied to the atom cloud to protect the imprint from interfering atoms. At a certain magnetic field, Hau says, interactions between the imprint and the rest of the atoms start to become repulsive, and the imprint separates from the cloud like a drop of oil in water. “This matter imprint digs a little hole for itself in the condensate,” Hau says. “It can snugly sit there for long periods of time.”
After waiting 1.5 seconds, the team revived the light beam. First, the researchers coaxed the matter imprint to the outside of the cloud by changing the magnetic field, and then they turned the control laser back on. The light beam that emerged from the atom cloud was weaker than the light beam that went in but similar in other regards, such as frequency and polarization, Hau says. Improving the stability of the magnetic field will likely lead to longer storage times, she adds.
Posted by Benjamin Roudenis on December 5, 2009 0 comments
It amazes me how many people still don’t run active protection against viruses, spyware and malware on their computers. Thanks to Microsoft, now there is no excuse!
Microsoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free download (Your PC must run genuine Windows to install Microsoft Security Essentials) from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It’s easy to tell if your PC is secure — when you’re green, you’re good. It’s that simple.
Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your Windows-based PC the way you want—without interruptions or long computer wait times.
Operating System: Genuine Windows XP (Service Pack 2 or Service Pack 3); Windows Vista (Gold, Service Pack 1, or Service Pack 2); Windows 7
Posted by Benjamin Roudenis on December 1, 2009 0 comments
Using a few ultracold ions, intense lasers and some electrodes, researchers have built the first programmable quantum computer. The new system, described in a paper to be published in Nature Physics, flexed its versatility by performing 160 randomly chosen processing routines.
Earlier versions of quantum computers have been largely restricted to a narrow window of specific tasks. To be more generally useful, a quantum computer should be programmable, in the same way that a classical computer must be able to run many different programs on a single piece of machinery.
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Researchers led by David Hanneke of the National Institute of Standards and Technology in Boulder, Colo., based their quantum computer on two beryllium ions chilled to just above absolute zero. These ions, trapped by an electromagnetic field on a gold-plated alumina chip, formed the quantum bits, or qubits, analogous to the bits in regular computers represented by 0s and 1s. Short laser bursts manipulated the beryllium ions to perform the processing operations, while nearby magnesium ions kept the beryllium ions cool and still.
Hanneke and colleagues chose 160 programs for the quantum computer to run. “We picked them, quite literally, at random,” Hanneke says. “We really wanted to sample all possible operations.”
The researchers ran each program 900 times. On average, the quantum computer operated accurately 79 percent of the time, the team reported in their paper, which was published online November 15. “Getting this kind of control over a quantum system is really interesting from a physics perspective,” Hanneke says.
