Fig. 2: Experimental setup. | npj Quantum Information

Fig. 2: Experimental setup.

From: Experimental implementation of secure anonymous protocols on an eight-user quantum key distribution network

Fig. 2

The entangled photon pair source is based on a type-0 MgO:ppLN crystal pumped bidirectionally by a 775.1 nm laser. A flip-mirror and motorised half wave plate (HWP) are used to couple a tunable telecom laser into the output fibre for polarisation control. The multiplexers/demultiplexers combine the shown combination of wavelength channels and distribute them to all eight users. The channel numbers are shown here plus 34 correspond to the standard ITU 100 GHz DWDM grid. Due to energy conservation photons in channels {1,−1}, {2,−2}, and so on are the only ones entangled. Each user is connected to the central hub by one fibre. The figure also shows the setup of each user’s polarisation analysis and detection module. (PBS Polarisation beam splitter, DM Dichroic mirror, SNSPD Superconducting nanowire single photon detector, TT Time tagger, BS non-polarising Beam Splitter.

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