Phase III – Stealth Is.

Scientists at the University of Glasgow have, for the first time, been able to drag light by slowing it down to the speed of sound and sending it through a rotating crystal.
Most people may think the speed of light is constant, but this is only the case in a vacuum, such as space, where it travels at 671million mph.
However, when it travels through different substances, such as water or solids, its speed is reduced, with different wavelengths (colours) travelling at different speeds.
In addition, it has also been observed, but is not widely appreciated, that light can be dragged when it travels through a moving substance, such as glass, air or water – a phenomenon first predicted by Augustin-Jean Fresnel in 1818 and observed a hundred years later.
Prof. Miles Padgett in the Optics Group in the School of Physics Astronomy, said: “The speed of light is a constant only in vacuum . When light travels through glass, movement of the glass drags the light with it too.

“Spinning a window as fast as you could is predicted to rotate the image of the world behind it ever so slightly. This rotation would be about a millionth of a degree and imperceptible to the human eye.”

In research detailed in the latest edition of the journal Science (“Rotary Photon Drag Enhanced by a Slow-Light Medium”), researchers Dr Sonja Franke-Arnold, Dr Graham Gibson and Prof Padgett, in collaboration with their colleague Professor Robert Boyd at the Universities of Ottowa and Rochester, took a different approach and set up an experiment: shining a primitive image made up of the elliptical profile of a green laser through a ruby rod spinning on its axis at up to 3,000 rpm.

Once the light enters the ruby, its speed is slowed down to around the speed of sound (approximately 741mph) and the spinning motion of the rod drags the light with it, resulting in the image being rotated by almost five degrees: large enough to see with the naked eye.

Dr Franke-Arnold, who came up with the idea of using slow light in ruby to observe the photon drag, said: “We mainly wanted to demonstrate a fundamental optical principle, but this work has possible applications too.
“Images are information and the ability to store their intensity and phase is an important step to the optical storage and processing of quantum information, potentially achieving what no classical computer can ever match.
“The option to rotate an image by a set arbitrary angle presents a new way to code information, a possibility not accessed by any image coding protocol so far.”

Article source: http://www.aleph9.com/Research/?p=167

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“Damage to cell division is characteristic of cancer, and it is therefore important to understand the causes of this damage,” notes Dr. Ben-Shlomo.

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The current research was carried out by placing lab mice into an environment where they were exposed to light for 12 hours and dark for 12 hours. During the dark hours, one group of mice was given artificial light for one hour. Changes in the expression of genes in the rodents’ brain cells were then examined.

Earlier studies that Dr. Ben-Shlomo carried out found that the cells’ biological clock is affected, and in the present research she revealed that the mode of cell division is also harmed and that the transcription of a large number of genes is affected. She states that it is important to note that those genes showing changes in their expression included genes that are connected to the formation of cancer as well as genes that assist in the fight against cancer. “What is certain is that the natural division is affected,” Dr. Ben-Shlomo clarifies.

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Quantum computers promise superfast calculations that precisely simulate the natural world, but physicists have struggled to design the brains of such machines. Some researchers have focused on designing precisely engineered materials that can trap light to harness its quantum properties. To work, scientists have thought, the crystalline structure of these materials must be flawlessly ordered — a nearly impossible task.

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One approach to quantum computing relies on entangling photons and atoms, or binding their quantum states so tightly that they can influence each other even across great distances. Once entangled, a photon can carry any information stored in the atom’s quantum state to other parts of the computer. To get that entangled state, physicists pin light in tiny cavities to increase the likelihood of quantum interaction with neighboring atoms.

Lodahl and his colleagues didn’t set out to trap light. They wanted to build a waveguide, a structure designed to send light in a particular direction, by drilling carefully spaced holes in a gallium arsenide crystal. Because the crystal bends light much more strongly than air does, light should have bounced off the holes and traveled down a channel that had been left clear of holes.

But in some cases, the light refused to move. It kept getting stuck inside the crystal.

“At first we were scratching our heads,” Lodahl says. “Then we realized it was related to imperfections in our structures.” If imperfect materials could trap light, Lodahl thought, then physicists could couple light and matter with much less frustration.

To see if disorder could help materials trap light, Lodahl and colleagues built a new waveguide, this time deliberately placing the holes at random intervals. They also embedded quantum dots, tiny semiconductors that can emit a single photon at a time, in the waveguide as a proxy for atoms that could become entangled with the photons.

quantum_peaksAfter zapping the quantum dots with a laser to make them emit photons, the researchers found that 94 percent of the photons stayed close to their emitters, creating spots of trapped light in the crystal. That’s about as good as previous results using more precisely ordered materials. Intuitively, physicists expect light to scatter in the face of disorder, but in this case colliding light waves built each other up and collected in the material.

Read More at Wired Science

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