A key ingredient in schemes for ultra-powerful quantum computers is entanglement, the strange link that allows two or more particles to share the same fuzzy quantum state. Entanglement would mingle together many quantum bits of information, each one stored in a single atom or other particle, allowing a quantum computer to break currently uncrackable encryption protocols, for example. A finicky entangled state can degrade, but researchers know a way to purify it. In this week's Nature a group reports the first purification of entangled atoms. Using ultraviolet laser pulses the researchers separately entangled two pairs of beryllium ions, and then entangled one ion from each pair. By measuring the quantum state of one of the original pairs the group could thereby purify the entanglement of the second.