Randomized Graph States and their Entanglement Properties
Abstract
We introduce a class of mixed multiqubit states, that corresponds to a randomized version of graph states. Such states arise when a graph state is prepared with noisy or imperfect controlled-Z gates. We study the entanglement features of these states by investigating both bipartite and genuine multipartite entanglement. Bipartite entanglement is studied via the concepts of connectedness and persistency, which are related to measurement based quantum computation. The presence of multipartite entanglement is instead revealed by the use of witness operators which are subsequently adapted to study nonlocal properties through the violation of suitable Bell inequalities. We also present results on the entanglement detection of particular randomized graph states, by deriving explicit thresholds for entanglement and nonlocality in terms of the noise parameter that characterizes the controlled-Z gates exploited for their generation. Finally, we propose a method to further improve the detection of genuine multipartite entanglement in this class of states.
Cite
@article{arxiv.1403.3828,
title = {Randomized Graph States and their Entanglement Properties},
author = {Jun-Yi Wu and Matteo Rossi and Hermann Kampermann and Simone Severini and Leong Chuan Kwek and Chiara Macchiavello and Dagmar Bruß},
journal= {arXiv preprint arXiv:1403.3828},
year = {2016}
}
Comments
This is the published version. We have added some text to clarify our results, corrected typos in references, and made some minor style modifications according to the journal