Submission + - Did D-Wave really demonstrate a quantum computer?
Qubert writes: Was D-Wave's quantum computer demo last week the real thing? Ars Technica takes a look inside the cold, black box and concludes that whatever was in there, it probably wasn't a 'pure' quantum computer: 'Jumping off the fence, we will say that we think D-Wave demonstrated a real device; however, we think their device is going to set off a debate in the physics community over where the boundary between classical and quantum computation is. At present, quantum computers are "globally phase coherent," which means that every qubit's state is entangled (and therefore correlated) with every other qubit... The D-wave system, however, is certainly not globally phase coherent, which raises the question of whether it is a quantum computer.'
