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Wednesday, August 07, 2002 Arrays of trapped atoms may function as quantum computer One- and two-dimensional arrays of neutral atoms have been trapped with each atom 125 micrometers from its neighbors. The set of traps is formed by an array of microlenses and each trap can be probed with additional laser beams to run quantum algorithms. In the experiments described, over 80 individual atoms are contained in their own traps. If each atom serves as one quantum bit, the size of this system compares favorably with the fewer than ten bits so far created in other implementations. To appear in Physical Review Letters   2:39:08 PM  Your views [] Close-up of atomic cave-dwellers Researchers have captured the most detailed pictures yet of particles crowded into an industrially useful nanoscale sponge. They extended an old method for analyzing x-ray diffraction data to a zeolite--a porous crystalline substance--filled with metal ions. The result confirms that this material is the first room-temperature stable electride, a class of compounds with curious electrical, magnetic, and optical properties that may eventually have applications as nanoscale devices. Read more at Physical Review Focus Journal article at Physical Review Letters   1:59:53 PM  Your views [] Carving plasma channels in air Firing ultrashort low-energy laser pulses through air causes ribbons of plasma up to 5 meters long but only 120 micrometers wide. The plasma consists of a soup of component electrons and nuclei ripped out of the atoms usually present in air. The authors suggest that the plasma channel could be kept open by firing more laser beams along its length. Journal article in Physical Review Letters   1:58:24 PM  Your views [] Reducing large-scale turbulence Addition of soluble polymers can have dramatic and useful effects on the flows of liquids, such as reducing viscosity, drag or turbulence. A new study shows how addition of polyethyleneoxide in concentrations of just a few parts per million can reduce large-scale turbulence while leaving small-scale fluctuations. The uses of this property are not yet explored but it could potentially allow better mixing of fluids without the associated inefficiencies of large-scale turbulence, or other applications. To appear in Physical Review Letters   1:57:20 PM  Your views [] 3-D x-ray microscope A relatively new x-ray imaging technique has made its first foray into the third dimension. Using a computer algorithm and high energy x-rays, researchers were able to visualize two nanometer-scale etched patterns stacked one on top of the other. Potential applications include imaging disordered materials and biological samples such as cells and viruses. Because the method doesn't require crystals it could potentially image single molecules, perhaps in conjunction with a free electron laser--a large facility that provides an x-ray laser beam. Read more at Physical Review Focus Journal article in Physical Review Letters   1:56:19 PM  Your views [] 3-D data storage in glass Storing data in three dimensions would dramatically increase the storage potential for many devices. However, most techniques have been limited by how deep data can be written inside a sample. A new technique manages to write structures inside silica glass to a depth of 5 millimeters using a single extremely short laser pulse. The technique may find initial uses not in data storage but in creating optical devices such as new types of lasers. Journal article in Applied Physics Letters   1:54:28 PM  Your views [] Asteroids show their colours A survey of the colours of more than 10,000 asteroids shows that the four main families of asteroids represent four main colour types. The distinct optical colours indicate that each family has a different origin but the similarities within a family suggest that each family comes from one source. Over 90% of asteroids are thought to belong to colour-segregated families. Read the preprint   1:53:06 PM  Your views [] Psychological Reactions to Terrorist Attacks Today's Journal of the American Medical Association reports a study into post-traumatic stress following the events of September 11, 2001. The objectives: "To assess psychological symptom levels in the United States following the events of September 11 and to examine the association between postattack symptoms and a variety of indices of exposure to the events." The conclusions: "One to 2 months following the events of September 11, probable PTSD [Post-Traumatic Stress Disorder] was associated with direct exposure to the terrorist attacks among adults, and the prevalence in the New York City metropolitan area was substantially higher than elsewhere in the country. However, overall distress levels in the country were within normal ranges. Further research should document the course of symptoms and recovery among adults following exposure to the events of September 11 and further specify the types and severity of distress in children." Read the full paper for details   9:59:52 AM  Your views [] Today is... 1807: First servicable steamboat, the Cleremont, embarks on first voyage 1802: Birth of Germain Henri Jess, Russian chemist who originated the field of thermochemistry 1903: Birth of Louis S. B. Leakey, archaeologist and anthropologist   9:27:36 AM  Your views [] Foam on the Rhine is not pollution The foam that clogs up the Rhine river is not due to pollution as often thought but to the chemical secretions of a plant, the water crowfoot,  reports Philip Ball in Nature Science Update. However the domination of the plant over other aquatic species could be due to human influences such as the introduction of phosphates into the river as byproducts of industrial and municipal endeavors. Just another example of how polluting behaviour can have indirect influences, even when we don't have a primary polluting effect...   7:57:37 AM  Your views [] < % radio.macros.weblogEditBox ()%>

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