Distilled entanglement brings long-distance quantum communication closer

Enlarge / Atoms are always up to something. (credit: Jurgen Appelo / Flickr)

This seems to be a good week for talking about quantum memories and distributing qubits. The thing about working with quantum states, though, is that you don't have much room to avoid messing it up. And, afterwards, figuring out when you've made a mistake is difficult. Once you make a measurement on a quantum system, there is no going back to its original state.

To get around this uncertainty, you have to find some way to increase your confidence that the operation you performed has actually turned out as expected. One option for this is called entanglement distillation. And entanglement distillation is exactly what a group in the Netherlands has recently demonstrated.

Impure diamonds are the best diamonds

This is a story about generating entangled quantum states in different locations. To understand how the researchers can do that, we need to see how a qubit state can be encoded in a bit of diamond. Most diamonds have a certain amount of nitrogen. The bonding between the carbon and the nitrogen leaves a rather unhappy electron. It is still bound to carbon, but the electron doesn't really want to be. So it floats around in between the carbon and the nitrogen atom.