Quantum networks usually rely on entangled photons to carry information, but inevitable photon loss makes communication error prone. These errors can be reduced if receiving nodes send out a signal, called a herald, each time an entangled photon arrives. However, waiting for such heralds and repeating any failed transmissions greatly slow communication. Now Gianvito Chiarella and his colleagues at the Max Planck Institute of Quantum Optics in Germany have shown how to mitigate the problem by producing heralds at sending nodes instead of at receiving nodes [1].
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