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To Catch A Fiber Optic Spy, Look At A Single Photon


Developments to Watch

To Catch a Fiber-Optic Spy, Look at a Single Photon

Absolute security for e-mail and other communications flowing over fiber-optic networks is almost at hand. Protecting traffic routed via telecom satellites could take a bit longer, but also seems attainable, says Andrew J. Shields, a senior scientist at Toshiba Research Europe Ltd. (TREL), the Cambridge (England) research arm of Japan's Toshiba Corp. On May 10, at the Conference on Lasers & Electro-Optics in San Francisco, Shields revealed that his team at TREL has developed a chip that can detect individual photons, or particles, of light.

The key to this remarkable feat is a photosensor covered with so-called quantum dots--tiny semiconductor domes just 30 nanometers wide. (The diameter of a human hair is roughly 100,000 nanometers.) Since the chip is able to detect single photons, it can protect information with quantum cryptography. Here's how that works: According to the laws of quantum physics, anything that tampers with a single photon alters its properties irreversibly. So, should anyone eavesdrop on information carried by a stream of individual photons, an immediate change would be apparent to the legitimate recipient. By inspecting each photon as it arrives, a recipient could spot any trouble en route--and alert the sender to stop transmitting.

"Despite the exotic name, quantum cryptography is not as distant a prospect as you might think," says Shields. For terrestrial fiber-optic applications, "we're aiming for commercialization of the detector in three years."

By about 2005, quantum physics could also be standing guard over satellite communications.By Otis Port; Edited by Ellen LickingReturn to top

Want to Quit Cigarettes? Gargle This

It sounds far-fetched, but someday all it may take to quit smoking is a capful of mouthwash several times a day. Researchers at the State University of New York at Buffalo's School of Dental Medicine are testing a novel mouth rinse that claims to make smoking taste terrible. There is also some evidence that the product might decrease plaque and prevent gum disease.

The new rinse works like any other mouthwash except for one thing: It makes cigarette smoke taste so bad that smokers can't get past the first puff. The effects are said to last 8 to 12 hours. According to Dr. Sebastian Ciancio, the dentist who is conducting the product trials, there is no one secret ingredient that gives the mouthwash its special properties. "It's the way the ingredients are combined that makes the difference," he explains. The formula will remain secret until its patent is awarded.

Unlike patches and gums already on the market, the rinse contains no nicotine, making it safe for pregnant women and patients with heart disease. In tests so far, the mouth rinse appears to spoil only the taste of tobacco smoke. Ciancio expects to finish his pilot study, on 20 patients, sometime this summer. There is no word yet on who will bring the product to market.Edited by Ellen LickingReturn to top

Mapping the Hidden Parts of the Heavens

Some light is finally being shed on dark matter--the invisible stuff that makes up as much as 90% of the universe, and has stumped astrophysicists for decades. They know it's there because there's not enough mass in the visible universe to account for the gravity that holds galaxies together. But it has never been seen.

Now, maps of the dark matter hidden in some heavenly regions have been plotted by a team led by scientists at Lucent Technologies' Bell Labs, the Kitt Peak National Observatory near Tucson, and the University of Michigan at Ann Arbor. Though the dark matter is invisible, astronomers were able to find it by looking for distortions in light emanating from 145,000 galaxies. Such distortions could be caused only by gravitational tugs from a massive but invisible force--dark matter. The team's findings are reported in the May 11 issue of Nature.

With more work, dark-matter maps may enable astrophysicists to determine the ultimate fate of the universe. Initial results seem to rule out one often-cited theory, dubbed Big Crunch: There doesn't appear to be enough matter to halt the universe's expansion and cause all the galaxies to collapse into an unimaginably dense blob, not even in a billion years. Whew.By Otis Port; Edited by Ellen LickingReturn to top


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