Berlin 2014 – scientific programme
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Q: Fachverband Quantenoptik und Photonik
Q 58: Quantum information: Concepts and methods IV
Q 58.5: Talk
Friday, March 21, 2014, 11:30–11:45, Kinosaal
Randomized Graph States and their Entanglement Properties — •Jun-Yi Wu1, Matteo Rossi2, Hermann Kampermann1, Leong Chuan Kwek3, Chiara Macchiavello2, and Dagmar Bruß1 — 1Institut für Theoretische Physik III, Heinrich-Heine-Universität Düsseldorf, D-40225 Düsseldorf, Germany — 2Dipartimento di Fisica and INFN-Sezione di Pavia, via Bassi 6, 27100 Pavia, Italy — 3Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
Graph states are a resource for measurement based quantum computation. We consider the situation that the graph state edges are generated by noisy controlled-Z gates, which work ideally with probability p, and operate as the identity map with probability (1−p). The total state after such a generation procedure is a convex combination of subgraph states. We call such mixtures randomized graph states. The randomized graph state obtained from a fully connected graph is the quantum counterpart of a classical random graph. In this work we study the properties of such randomized graph states. We show that randomized graph states are not maximally connected and less persistent than the ideal graph states (p=1). We show that for randomness p greater than a certain critical value pc, a randomized graph state is genuine multipartite entangled. An upper bound on the critical value pc can be obtained with the help of a witness operator.