Entanglement extraction A Letter to Nature by Takashi Yamato et al. describes a rather ingenious way of recovering the entanglement of a photon pair where the entanglement has been lost by environmental decoherence. They do this by by distributing not one, but two sets of independently generated entangled photon pairs through the system at the same time. The scheme constructed by the authors is the quantum equivalent of a parity check operation in conventional digital information processing — a potentially useful component of future quantum information processing systems