Identifying Phases of Quantum Many-Body Systems That Are Universal for Quantum Computation

School of Physical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
Physical Review Letters (Impact Factor: 7.51). 08/2009; 103(2):020506. DOI: 10.1103/PhysRevLett.103.020506
Source: PubMed


Quantum computation can proceed solely through single-qubit measurements on an appropriate quantum state, such as the ground state of an interacting many-body system. We investigate a simple spin-lattice system based on the cluster-state model, and by using nonlocal correlation functions that quantify the fidelity of quantum gates performed between distant qubits, we demonstrate that it possesses a quantum (zero-temperature) phase transition between a disordered phase and an ordered "cluster phase" in which it is possible to perform a universal set of quantum gates.

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    • "Notice that H clu has a Z 2 × Z 2 symmetry generated by the following two operators (see e.g. [32] [33] [34] "
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