Abstract

We demonstrate that a special class of highly entangled multi-partlicle states, the cluster states [1], can serve as quantum computers [2]. Cluster states can be created in arrays of qubits with an Ising-type interaction, e.g. with ultracold atoms in optical lattices. It is shown that a universal set of quantum gates, the CNOT and arbitrary one-qubit-rotations, can be implemented only by performing one-qubit measurements. Further, these gates can be combined to form quantum logic networks. Cluster states form the “substrate” for a quantum logic network. The network is imprinted on the quantum state by one-qubit measurements. The cluster state is used up by the computation since the measurements destroy it. Thus, cluster states form a resource for quantum computation. The picture that emerges is that a cluster state can be viewed as a one-time quantum computer, and the set of performed measurements being the programme.

© 2001 EPS