Quantum computer that 'computes without running' sets efficiency record

(Phys.org)--Due to quantum effects, it's possible to build a quantum computer that computes without running--or as the scientists explain, "the result of a computation may be learned without actually running the computer." So far, however, the efficiency of this process, which is called counterfactual computation (CFC), has had an upper limit of 50%, limiting its practical applications.