The first quantum memory that stores and releases entanglement has been built by researchers at the University of Geneva.

Their device consists of neodymium atoms buried in a crystal of ytterbium silicate, which when cooled, can absorb and store photons.They created a pair of entangled photons, sent one into the crystal and waited until it was emitted again. They were then left with this new photon and the original member of the pair. They then carried out a standard experiment, known as a Bell test, and proved that the pair were still entangled.

“That’s impressive for several reasons. For a start, for the entanglement to be preserved, the entire crystal has to be involved. This crystal is about a centimetre in size and the idea that entanglement can be exchanged between a photon and an object of this size is amazing…. But the most exciting aspect of all this is that the entanglement survives the process of storage and release at all. Notoriously fragile, entanglement leaks into the environment like water through a sieve. Being able to store and release it is the enabling technology that could make devices such as quantum repeaters.. [and] the quantum Internet… work.”

Ref: arxiv.org/abs/1009.0489: Quantum Storage of Photonic Entanglement in a Crystal