Patent ID: 8227830

Claim:
A photon source comprising a photon source body comprising at least one quantum dot; electrical contacts positioned to allow an electric field to be applied across said at least one quantum dot; and a pulsed bias source configured to cyclically generate a pulse having at least first and second bias levels, said pulsed bias source connected to said contacts and cyclically applying said pulse across said electrical contacts to alter the field across said at least one quantum dot and inject electron and hole carriers in said quantum dot, said pulsed bias source generating each pulse with an amplitude of said first bias level sufficient for emission of radiation by radiative recombination and applying said first bias level for a predetermined time duration shorter than the radiative decay time at which a photon at a particular wavelength is generated, thereby to produce at most a single photon at said particular wavelength by radiative recombination of carriers in said quantum dot, said pulsed bias source generating and applying said second bias level, which is of lower amplitude than said first bias level, and which changes the carrier state in the quantum dot to suppress emission of photons at said particular wavelength.