Measuring bipartite quantum correlations of an unknown state.


We report the experimental measurement of bipartite quantum correlations of an unknown two-qubit state. Using a liquid state Nuclear Magnetic Resonance setup and employing geometric discord, we evaluate the quantum correlations of a state without resorting to prior knowledge of its density matrix. The method is applicable to any 2 ⊗ d system and provides, in terms of number of measurements required, an advantage over full state tomography scaling with the dimension d of the unmeasured subsystem. The negativity of quantumness is measured as well for reference. We also observe the phenomenon of sudden transition of quantum correlations when local phase and amplitude damping channels are applied to the state.

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@article{Silva2013MeasuringBQ, title={Measuring bipartite quantum correlations of an unknown state.}, author={Isabela Lorena Alfenas da Silva and Davide Girolami and Ruben Auccaise and Roberto S. Sarthour and I Oliveira and Tito J. Bonagamba and E. R. deAzevedo and Diogo De O. Soares-Pinto and Gerardo Adesso}, journal={Physical review letters}, year={2013}, volume={110 14}, pages={140501} }