A team of scientists at the Rowland Institute in Massachusetts, led by Prof Lene Hau, have succeeded in making a pulse of laser light slow down to a complete halt. Then, after about a thousandth of a second, they made it start up again as if nothing had happened. This breakthrough will be important for designing the supercomputers of the future.
Other scientists, at Stanford University and the University of Colorado, have worked on similar techniques, and a group at Texas A & M University hopes to not only stop light, but reverse its direction.
Hau and his group chilled sodium atoms to one-millionth of a degree above absolute zero to create a Bose-Einstein Condensate, in which the atoms expand and overlap and become entangled so that they act like a single superatom. When a pulsed laser probe is shot into the condensate, the yellow laser light is cut from 186,000 miles per second to a crawl.
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Antimatter atoms, the most elusive matter in the universe, have been captured for the first time.
According to quantum physics, every particle has a corresponding antiparticle with the same mass and opposite charge. The pair destroy each other on contact, releasing a burst of energy.
Scientists want to harness this energy, but they have found it difficult to make and control antiatoms. They move at almost the speed of light, which is much too fast to be stored or studied. Now researchers at CERN, the European Laboratory for Particle Physics near Geneva, Switzerland, think they have made and stored thousands of antiatoms in a particle trap. Gerald Gabrielse of Harvard University, and his research team used powerful magnetic fields to trap antiprotons. They then introduced a beam of antielectrons, or positrons, and used an electric field to slow them down and bring the two types of particles together.
Some particles failed to move, suggesting that the positively and negatively charged antiparticles had bound together into neutral atoms. Gabrielse can?t be sure how many atoms they trapped, but says they would only produce a tiny amount of energy?not even enough to warm a cup of coffee?so the invention of the antimatter-powered auto is not yet a reality.
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