PerspectivePhysics

Directing Light Emission from Quantum Dots

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Science  20 Aug 2010:
Vol. 329, Issue 5994, pp. 910-911
DOI: 10.1126/science.1194352

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Summary

Cell phones, radios, and television sets contain antennas that pick up signals carried by electromagnetic radiation and convert them into pulses of electric current. Antennas connect two very different length scales—transmission wavelengths range from centimeters to meters, whereas component wiring and circuitry is on the micrometer-to-millimeter scale. On page 930 of this issue, Curto et al. (1) take this scaling concept to the optical world, where the interaction of light with matter includes quantum mechanics as well as classical electromagnetism. They fabricate nanoantennas from gold, a metal that can develop charge oscillations in its surface layers when excited by optical radiation. These antennas allow visible radiation, which has wavelengths of hundreds of nanometers, to couple into a semiconductor quantum dot only a few nanometers in diameter, and also direct the emission.