Efficient growth of complex graph states via imperfect path erasure
Abstract
Given a suitably large and well connected (complex) graph state, any quantum algorithm can be implemented purely through local measurements on the individual qubits. Measurements can also be used to create the graph state: path erasure techniques allow one to entangle multiple qubits by determining only global properties of the qubits. Here, this powerful approach is extended by demonstrating that even imperfect path erasure can produce the required graph states with high efficiency. By characterizing the degree of error in each path erasure attempt, one can subsume the resulting imperfect entanglement into an extended graph state formalism. The subsequent growth of the improper graph state can be guided, through a series of strategic decisions, in such a way as to bound the growth of the error and eventually yield a highfidelity graph state. As an implementation of these techniques, we develop an analytic model for atom (or atomlike) qubits in mismatched cavities, under the doubleheralding entanglement procedure of Barrett and Kok (2005 Phys. Rev. A 71 060310). Compared to straightforward postselection techniques our protocol offers a dramatic improvement in growing complex highfidelity graph states.
 Publication:

New Journal of Physics
 Pub Date:
 June 2007
 DOI:
 10.1088/13672630/9/6/196
 arXiv:
 arXiv:quantph/0702209
 Bibcode:
 2007NJPh....9..196C
 Keywords:

 Quantum Physics
 EPrint:
 15 pages, 10 figures (which print to better quality than when viewed as an on screen pdf)