Entangled memories
Diagram of the Caltech memaory for storing two entangled photon states. The entangled states are created by a beam splitter (left) before being sent into a extremely cold gas of caesium atoms (centre). A laser pulse creates imprints of the entangled states, which move slowly through the gas. The entangled photon states are recovered by applying a second pulse, and the entanglement verified by a phase shifter and photon detector (right). (Courtesy: Nature).