A PHOTONIC DOT MOLECULE, a pair of photons inside two interconnected boxes each acting as an artificial atom, has been constructed, opening new possibilities for fine-tuning the colors of light coming out of certain lasers. Having built two identical, micron-sized blocks of gallium arsenide, each with a light-producing quantum well, a German-US-Russian collaboration (Thomas Reinecke, Naval Research Laboratory, 202-767-2594) studied what happened when the two GaAs blocks were connected. In isolation, each photonic dot acted as a small confined area (a "microcavity") for light; photons with wavelengths roughly equal to the spaces between two of the cavity walls could bounce back and forth between them. When the two microcavities were connected, the researchers noticed a new, larger set of photon wavelengths, slightly different from the original ones. A highly analogous situation occurs with the wavelengths of electrons when the negatively charged particles group together in an atom or molecule. (Bayer et al., Physical Review Letters, 21 September 1998; see also Physical Review Focus, 28 September 1998, )