Patent ID: 6884990
Filing Date: 2005-04-26
Classification: G02F,H04L

Abstract:
1. A method for changing the polarization of at least one of the photons emitted from a photon pair source into various partial ray paths using an electro-optical modulator, which is positioned in a first ray path being traversed by the photon to be influenced and which, in the activated state, is able to alter the polarization of a photon, wherein the modulator is activated as a function of time such that the probability that the photon is found in the region of the electro-optical modulator in the activated state is at a maximum, and the modulator must be deactivated following passage through the maximum, the photon-pair source being an optically non-linear crystal that is pumped using a pulsed laser, and the instant when the modulator is activated (activation instant) being determined from the pulse-repetition rate and from the optical path length from the crystal to the electro-optical modulator; and/or the activation instant for influencing the one photon being determined from the registration instant of the other photon, the other photon being registered without being destroyed.