Abstract: A method for polarization alignment, preferably for and/or in the case of optical communication, quantum cryptography and/or quantum computing, comprising a source (2) for generating polarization-entangled photon pairs and two detection modules (3, 4), wherein the source (2) for transmitting the photons is connected via in each case one quantum channel (5) to the two detection modules, and wherein each detection module measures the polarization of the photons in two non-orthogonal bases, and including a polarization compensation unit (6) for polarization alignment of the polarization change during the transmission of the photons via the quantum channels, wherein the polarization compensation unit (6) has several optical components. The polarization alignment is effected by a downhill simplex algorithm and/or by a deterministic algorithm.

Abstract: A method for quantum communication between at least three receivers includes: i) generating an entangled photon pair in a source (2) with a signal photon in a signal wavelength range and an idler photon in an idler wavelength range, ii) assigning the signal and idler photons to the quantum channels (4) on the basis of their wavelength; iii) transmitting the photon pair to the receivers (3) via the quantum channels (4); iv) detecting the photon pair at the receivers (3).