Entanglement on ice

摘要

Communication over long distances needs repeaters - for classical communication these are devices that receive input data and retransmit them. In an important move towards long-distance communication of quantum information, two groups1'2 (pages 508 and 512 of this issue) have demonstrated the basic building block of a solid-state quantum repeater. The authors have managed to put entangled photons 'on ice'. That is, they were able to show that they could keep a pair of photons entangled, even after storing and retrieving one of the photons in a cryogenically cooled crystal.