Steinlechner, Fabian OliverFabian OliverSteinlechnerMarques Muniz, André LuizAndré LuizMarques Muniz2023-12-112023-12-112023-04-05https://publica.fraunhofer.de/handle/publica/457842It is claimed a method of low loss routing for quantum communication, comprising a single photon source (1) and/or a weak coherent light source (1) for decoy state quantum key distribution, a router (3), two or more receivers (5), and a quantum network connecting each receiver (5) via a quantum channel (4) with the router (3), whereby the method comprises the stepsi) generation of a quantum state in the source (1) and transmission of the quantum state to the router (3), whereby the quantum state is a single photon and/or a weak coherent light pulse;ii) allocation of the quantum state based on the wavelength of the quantum state to a quantum channel (4) by the router (3);iii) transmission of the quantum state via the quantum channel (4) to a receiver (5);iv) detection of the quantum state at the receiver (5) in order to establish a quantum communication between the source (1) and the receiver (5);According to the invention the source (1) comprises a modification means (2), and the source (1) is connected with the router (3) via a multi-wavelength quantum channel (6), and the modification means (2) set the wavelength of the generated quantum state in step i) in order to enable a specific allocation of the quantum state in step ii) to a specific quantum channel (4) to a specific receiver (5), in order to enable a quantum communication between the source (1) and the specific receiver (5).enpatentEP4160976 A1EP20210200138