A light bulb isnt very useful without a reliable on/off switch. The same holds true for quantum dots. These ultra tiny electronic nanostructures someday may serve as the ones and zeros used by a superfast quantum computer, but first physicists need to refine their ability to turn quantum dots "on" and "off."
In the June 23, 2003, on-line issue of Applied Physics Letters, researchers from the National Institute of Standards and Technology (NIST) and the National Renewal Energy Laboratory (NREL) take a step in the right direction. They report a way to measure accurately the amount of laser light needed to shift the electrons in a particular type of quantum dot between two discrete states, a low energy, ground state and a higher energy, excited state.
The strength of the interaction between quantum dots and electromagnetic waves like laser light is affectionately known in physical science circles as the "dipole moment." Loosely translated, its a number that tells you how easy the dots are to excite.
Fred McGehan | EurekAlert!
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