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September 28, 2006

Bose-Einstein condensation in the solid state

New experimental research shows that half-matter, half-light quasi-particles called polaritons show compelling evidence of Bose-Einstein condensation at the relatively high temperature of 19 degrees Kelvin. The creation of a polariton Bose-Einstein condensate in the solid state provides scientists with a unique opportunity to better understand and possibly exploit the quantum effects that occur in these very special conditions.


Images of the energy distribution of polaritons as a function of the excitation density. From left to right, below threshold for condensation, at threshold and above threshold. Front row, speed distributions, the speed increases from the center to the edges. Rear row, dispersion of polaritons, with their distribution.Credit: Benoit Devead-Pledran, EPFL

A polariton is a billion times lighter than a Rubidium atom, and 10,000 times lighter than an electron. This means that polaritons can transform into a Bose-Einstein condensate at a much higher temperature than alkali gases. Some of the possibilities that have been suggested for applications of the quantum effects of the Bose-Einstein phase -- quantum computing, quantum clocks or atomic or lasers that use matter instead of light – are only realistically conceivable if these condensates can be achieved at room temperature, or at least temperatures that can be reached using standard cryogenic techniques. According to Professor Benoit Deveaud, leader of the research team, condensates at even higher temperatures could perhaps be achieved using other semiconductor materials.

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