PerspectivePhysics

The Super of Superradiance

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Science  18 Sep 2009:
Vol. 325, Issue 5947, pp. 1510-1511
DOI: 10.1126/science.1176695

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Summary

In 1954, Robert Dicke introduced the concept of superradiance in describing the cooperative, spontaneous emission of photons from a collection of atoms. The concept of superradiance can be understood by picturing each atom as a tiny antenna emitting electromagnetic waves. Thermally excited atoms emit light randomly, and the emitted intensity is a function of the number of atoms, N. However, when the atomic “antennas” are coherently radiating in phase with each other, the net electromagnetic field is proportional to N, and therefore, the emitted intensity goes as N2. As a result, the atoms radiate their energy N times faster than for incoherent emission. It is this anomalous radiance that Dicke dubbed “superradiance” (13).