A single-photon light-emitting diode

A Single-Photon Light-Emitting Diode has been created. At the May CLEO/QELS meeting in Long Beach, California, scientists from Toshiba Research Europe Ltd described a nanometer-scale indium arsenide quantum dot integrated into a conventional gallium arsenide LED structure. Using a pulse of electric current, the researchers could induce a single electron and a single hole to recombine in the dot, thus generating a single photon. Because the exciton’s lifetime was 1.0 ns and the equipment had subnanosecond time resolution, the physicists could verify that photons were emitted singly. The researchers believe this is the first electrically driven single-photon source. Such single-particle-emitting sources could offer a potentially inexpensive and convenient component for quantum cryptography and other applications. (Paper QTuG1 at the meeting; see also Z. Yuan et al., Science 295, 102, 2002 http://dx.doi.org/10.1126/science.1066790 .)