When people have a difficult problem they often talk about “shining a light on it.” Creating and controlling high-temperature superconductors has been a problem for scientists and engineers for over two decades. Now, Yoram Dagan, a professor at Tel Aviv University’s (TAU) Department of Physics and Center for Nanoscience and Nanotechnology, has made a breakthrough in superconductors by literally shining a light on them. By doing this, he is able to control their properties.
Superconductors are one of those seemingly magical materials. When a conducting material, such as copper or silver, is cooled, its ability to conduct electricity increases. Bring a copper wire down to the temperature of absolute zero (0° K, −273.15° C, −459.67° F) and its electrical resistance will be extremely low, but it will still have some. A superconductor is something very different. If a superconducting material is cooled to below a particular critical temperature, then all of its resistance vanishes. It becomes exactly zero. That means that a loop of superconducting material can conduct an electrical current around and around inside of itself forever.
via gizmag
September 3, 2012
