Tag Archives: nature materials

Laser experiments may lead to faster computer chips

So long silicon: Laser experiments may lead to faster computer chips

Smarter America

Published July 29, 2013

  • faster electron transfer.jpg

    An optical laser pulse (the red streak) shatters the ordered electronic structure (blue) in an insulating sample of magnetite, switching the material to electrically conducting (red) in one trillionth of a second. (Greg Stewart/SLAC)

So long silicon! A small change in the design of a computer chip could soon lead to the creation of smaller, faster and far more powerful computers.

Researchers at the U.S. Department of Energy’s SLAC National Accelerator Laboratory reported that magnetite, a naturally magnetic mineral — the most magnetic of all the minerals on Earth — was found to have the fastest-possible electrical switching time. Electrical switching, or moving a “switch” from a non-conductive state to a conductive one, is the process that makes our current electrical circuits.

The team of scientists used SLAC’s Linac Coherent Light Source (LCLS) X-ray laser and found that that it takes only 1 trillionth of a second – thousands of time faster than current transistors – to flip the on-off electrical switch in samples of magnetite.

The findings were published July 28 in Nature Materials, a scientific journal.

According to Roopali Kukreja, the lead author of the study and a materials science researcher at Stanford University, this project unveiled the so-called “speed limit” for electrical switching in this material.

Researchers say that when the laser pulse struck the sample, the electronic structure was rearranged into non-conducting “islands” surrounded by electrically conducting regions, hundreds of quadrillionths of a second later.

First, scientists hit the samples with a visible-light laser, fragmenting the material’s electronic structure at an atomic scale, which rearranged it and formed the islands. Following closely by an ultrabright, ultrashort X-ray pulse in adjusted intervals, they measured how long it took for the material to switch from a non-conducting to an electrically conducting state.

The magnetite samples were then cooled to -190 degrees Celsius, locking the molecular changes in place, according to Kukreja. Follow-up studies were conducted on a hybrid material that exhibits ultrafast switching properties at room temperature, making it more commercially viable than magnetite. Future experiments will attempt to identify other compounds and techniques to induce electrical switching, possibly creating superior transistors.

With a global search underway for new materials that go beyond modern semiconductor transistors, the LCLS x-ray could help hone in on processes that occur at the atomic size, according to Hermann Dürr, the principal investigator of the LCLS experiment and senior staff scientist for the Stanford Institute for Materials and Energy Sciences.

This experiment shows that although magnetite’s magnetic properties have been known for thousands of years, there is a lot that can still be learned, notes Dürr.

Read more: http://www.foxnews.com/tech/2013/07/29/experiment-with-laser-shows-possible-replacement-for-silicon-chips/?intcmp=trending#ixzz2abUfnPnx


Filed under Humor and Observations

Invisibility Cloak Invented


Invisibility cloak now a reality, scientists say


Published November 13, 2012


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    Nov. 12, 2012: A member of the lab at Duke University’s Pratt School of Engineering has made a giant leap toward creating an invisibility cloak. (Duke University)

Let’s hope Star Fleet perfects the technology before the Romulans get their hands on it.

Scientists have made the impossible possible, disappearing a cylinder by guiding light around it before putting those photons back on their original path — essentially bending light around the object. This new approach achieves invisibility where others have failed. With a catch, however: It only works from one direction.

The math is incredibly complex and the materials necessary difficult to produce. And while the underpinning concepts allow invisibility in microwaves and hold promise for radar, it won’t be easy to make it work at optical wavelengths, cautioned Duke University’s Nathan Landry and John Pendry of London’s Imperial College, who published their results in the journal Nature Materials.

‘We built the cloak, and it worked.’

– Nathan Landy, a graduate student at Duke’s Pratt School of Engineering

Still, it’s a breakthrough six years in the making. The team made their initial discovery in 2006, a new approach to “transportation optics”: artificially structured stuff called meta-materials designed with specific properties. In this case, they move light around in particular ways to shape an electromagnetic signature, hiding an object from radar and some types of cameras.

Their “cloaking” concept ignited a meta-materials research boom and the field of invisibility exploded. But most of the most promising approaches to rely on meta-materials that reflect some of the incident light, making invisibility impartial.

This involved seeing a reflection of what lies behind an object. Now this team has introduced a diamond-shaped cloak allowing the edges to match up.

By doing so, they bent light around their 1 centimeter high, 7.5 centimeter wide cylinder without reflections.

“We built the cloak, and it worked,” said Landy, a graduate student working in the laboratory at Duke’s Pratt School of Engineering. “It split light into two waves which traveled around an object in the center and re-emerged as the single wave minimal loss due to reflections.”

There are drawbacks to even this research effort, of course. It can only hide objects so small they are not visible to the naked eye, and that success has predominantly been in wavelengths longer than what the eye can, see such as infrared, microwaves and radio.

Although media reports have hyped the breakthrough as producing an invisibility cloak for Harry Potter, this is not the case. The ultimate result would not be flexible material.

It may prove a whole lot easier to hide objects from other waves such as from heat, magnetic fields or acoustics — think a “Get Smart” cone of silence.

For defense applications, much of the research focuses on meta-materials to make platforms from tanks, planes and helicopters to light tactical vehicles invisible – at least to certain light and sound wavelengths. BAE’s Adaptiv technology has shown huge promise in this area.

Next stop, invisible jet? Has anyone told Wonder Woman?

Ballet dancer turned defense specialist Allison Barrie has traveled around the world covering the military, terrorism, weapons advancements and life on the front line. You can reach her at wargames@foxnews.com or follow her on Twitter @Allison_Barrie.

Read more: http://www.foxnews.com/science/2012/11/13/invisibility-cloak-now-reality-scientists-say/#ixzz2C8l854KB

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Filed under Humor and Observations