QUANTUM ERROR CORRECTION AND FAULT-TOLERANT QUANTUM COMPUTING

摘要

We review the theories of quantum error correction, and of fault-tolerant quantum computing, and show how these powerful tools are combined to prove the accuracy threshold theorem for a particular error model. One of the theorem's assumptions is the availability of a universal set of unencoded quantum gates whose error probabilities P_e fall below a value known as the accuracy threshold Pa. For many, P_a ~ 10~(-4) has become a rough estimate for the threshold so that quantum gates are anticipated to be approaching the accuracies needed for fault-tolerant quantum computing when P_e< 10~(-4). We show how controllable quantum interference effects that arise during a type of nonadiabatic rapid passage can be used to produce a universal set of quantum gates whose error probabilities satisfy Pe < 10~(-4). We close with a discussion of the current challenges facing an experimental implementation of this approach to reliable universal quantum computation.