Demonstrating the viability of universal quantum computation using teleportation and single-qubit operations

Algorithms such as quantum factoring(1) and quantum search(2) illustrate the great theoretical promise of quantum computers; but the practical implementation of such devices will require careful consideration of the minimum resource requirements, together with the development of procedures to overcome inevitable residual imperfections in physical systems(3-5). Many designs have been proposed, but none allow a large quantum computer to be built in the near future(6). Moreover, the known protocols for constructing reliable quantum computers from unreliable components can be complicated often requiring many operations to produce a desired transformation(3-5,7,8). Here we show how a single technique-a generalization of quantum teleportation(9)-reduces resource requirements for quantum computers and unifies known protocols for fault-tolerant quantum computation. We show that single quantum bit (qubit) operations, Bell-basis measurements and certain entangled quantum states such as Greenberger-Horne-Zeilinger (GHZ) states(10)-all of which are within the reach of current technology-are sufficient to construct a universal quantum computer. We also present systematic constructions for an infinite class of reliable quantum gates that make the design of fault-tolerant quantum computers much more straightforward and methodical.