THE POWER OF DISCORD

The notion that quantum computing can be done only through entanglement was cemented in 1994, when Peter Shor, a mathematician at the Massachusetts Institute of Technology in Cambridge, devised an entanglement-based algorithm2 that could factorize large numbers at lightning speed - potentially requiring only seconds to break the encryption currently used to send secure online communications, instead of the years required by ordinary computers. The trouble was that the computations were done at room temperature, using liquid-based nuclear magnetic resonance (NMR) systems, in which information is encoded in atomic nuclei using an internal quantum property known as spin. According to the orthodoxy, no entanglement meant no quantum computation.