Achieving 'perfect' molecular discrimination via coherent control and stimulated emission

We illustrate how stimulated emission near threshold can turn modest coherent control yields into essentially perfect discrimination between systems. We demonstrate selective two-photon driven superfluorescence in atomic Rb and Na, where the shape of an ultrafast drive laser controls which atoms superfluoresce. Furthermore, we demonstrate high contrast selectivity in driving stimulated emission from dye molecules in solution by tailoring the shape of the ultrafast drive laser pulse. In both cases, we demonstrate discrimination with a control factor of about 10⁴.