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Publication appeared in Nature Photonics
Six photons are created simultaneously by using higher-order emissions in an SPDC process. The photons pass through a narrowband filters, are coupled to single-mode fibres, and are then brought to beamsplitters. The reflected modes are analysed in the |H/Vright fence basis and in the | ± right fence basis, respectively, using polarizing beamsplitters (PBS) and a half-wave plate (HWP) orientated at 45°. State characterization of the heralded photon pair in the transmitted modes is performed through polarization analysis using quarter-wave plates (QWPs), HWPs and PBSs.