Abstract

Many attempts to realize elementary quantum-logic operations as well as the feasible schemes for quantum cryptography and teleportation are based on the availability of few (or single) photons in a well defined mode of the radiation field. So far, most employed schemes used for the photon generation rely on spontaneous emission events or on parametric down conversion and produce photons at more or less random times. Only recently, different photon generation schemes have been demonstrated, like a single-photon turnstile device, based on the Coulomb blockade mechanism in a quantum dot, the fluorescence excitation of a single molecule or the excitation of single colour centres (Nitrogen vacancies in diamond). All these new schemes emit photons upon an external trigger event. However, the photons are spontaneously emitted into many modes of the radiation field and usually show a broadband energy distribution.

© 2000 IEEE