Nothing from nothing leaves nothing

Or so Billy Preston sang about 30 years ago. Anyway, we all understand that quantum physics is strange but sometimes it is just incomprehensible. In this Nature article, Philip Ball explains the research of two English physicists on the
ultimate no-brainer; that is, the logical proposition that a quantum computer, building on the concept of superpositions to what they term counterfactual computation, could arrive at a computational result without ever being switched on. Unfortunately, only an abstract of the original research is online.