Method and device for producing a choice of either single photons or pairs of photons in an optical channel

US6430345B1 · kind B1 · utility

Assignee

• DEUTSCHE TELEKOM AG · DE

Inventors

• Wolfgang Dultz · Frankfurt am Main, DE
• Gisela Dultz · Frankfurt am Main, DE
• Helmar A. Becker · Hanau, DE
• Heidrun Schmitzer · Grünhain, DE

Key dates

• Filing date: Sep 27, 2000
• Grant date: Aug 6, 2002
• Expiry date: Sep 27, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F3/00
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method and device for generating a choice of individual photons or photon pairs in an optical channel. The generation of this choice involves generating a two-photon state corresponding to a photon pair and spatially separating the photon pair while preserving the quantum-mechanical correlation, in the event the photons are emitted in a collinear manner. One photon is coupled into one optical channel each, the one channel containing an interferometer with variable optical path-length difference &dgr;1F−&dgr;1S, and the other channel including an optical delay section having the optical length &dgr;1. The channels are spatially reunited through a beam splitter, and an adjustment of the quantities &dgr;1F, &dgr;1S, and &dgr;1 occurs in such a way that the probability K for coincidences between the outputs of the beam splitter is a choice of approximately K=0 or approximately K=1, or approximately a predetermined intermediate value, with K=0 corresponding to a photon pair in one of the output channels of the beam splitter, and K=1 corresponding to two individual photons in both output channels of the beam splitter. With this choice generation, an optical separating filter or g…