An optical source, a method for generating optical pulses, a quantum communication system, and a quantum communication method

A phase-randomised light source comprises a master light source 403, a slave light source 402 and an interferometer 900. The master light source emits a series of master light pulses. Phase randomisation of the pulses is achieved by overlaying a phase modulation perturbation signal onto a master las...

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Bibliographische Detailangaben
Hauptverfasser: Robert Ian Woodward, Marco Lucamarini, Zhiliang Yuan, Andrew James Shields
Format: Patent
Sprache:eng
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Beschreibung
Zusammenfassung:A phase-randomised light source comprises a master light source 403, a slave light source 402 and an interferometer 900. The master light source emits a series of master light pulses. Phase randomisation of the pulses is achieved by overlaying a phase modulation perturbation signal onto a master laser control signal (Fig. 10a) Different phase modulations are applied to adjacent master pulses. The slave light source receives the master light pulse and generates successive sequences of pulses. There is one sequence of slave pulses per master pulse. Preferably, there are three pulses per sequence (see Fig. 10c). There is random relationship between the phase of light pulses in a first sequence and the phase of light pulses from a subsequent sequence. An interferometer 900 with a delay element 903 receives the sequences of slave light pulses. The interferometer outputs an interfered pulse train comprising groups of (preferably three) pulses (Fig. 10d). Each group comprises a first and a second output pulse that have a first and second predetermined amplitude respectively and a predetermined relative phase between them. A third output pulse of the group may have a randomised amplitude. It is suitable for testing the quality of phase randomization.