Quantum control: How weird do you want it?
Physics 10 September 2014
By Michael Brooks
Video: Quantum discord: entanglement's noisy twin
Entanglement used to be the gold standard of the quantum world's weirdness, now a new and noisy phenomenon could give us all the benefits with less of the fuss
RAYMOND LAFLAMME works in a magnificent-looking building. The Quantum-Nano Centre on the University of Waterloo campus in Ontario, Canada, boasts an exterior whose alternating strips of reflecting and transparent glass are designed as metaphors for the mysterious nature of the quantum world. Inside, it is even more impressive. Its labs are so well isolated from the outside world that an earthquake will barely move their floors. No electric or magnetic fields can get in where they aren't wanted, and the temperature is controlled to within a single degree. That's especially impressive, considering that human beings bring their hot bodies into the centre to perform experiments at temperatures close to absolute zero.
What a shame, then, if all this cutting-edge engineering proves entirely superfluous. Laflamme heads the university's quantum computing institute. Ironically, he was among the first researchers to show why quantum computing might not require the kinds of isolation we once thought. If the latest raft of results is anything to go by, the key to accessing the quantum world may lie not in avoiding disturbance, but embracing it.
Our emerging understanding of the way quantum systems are connected suggests that there is much more to being quantum than we realised. Researchers have given this phenomenon the name quantum discord. If it turns out to be all that it currently seems, discord may finally tell us …
Article amended on 19 September 2014
When this article was first published, it ascribed too fine control to "Alice"'s photonic manipulations.