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arXiv · 1202.0235

Experimental implementation of a NMR entanglement witness

J. G. Filgueiras·T. O. Maciel·R. E. Auccaise·R. O. Vianna·R. S. Sarthour·I. S. Oliveira
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Abstract

Entanglement witnesses (EW) allow the detection of entanglement in a quantum system, from the measurement of some few observables. They do not require the complete determination of the quantum state, which is regarded as a main advantage. On this paper it is experimentally analyzed an entanglement witness recently proposed in the context of Nuclear Magnetic Resonance (NMR) experiments to test it in some Bell-diagonal states. We also propose some optimal entanglement witness for Bell-diagonal states. The efficiency of the two types of EW's are compared to a measure of entanglement with tomographic cost, the generalized robustness of entanglement. It is used a GRAPE algorithm to produce an entangled state which is out of the detection region of the EW for Bell-diagonal states. Upon relaxation, the results show that there is a region in which both EW fails, whereas the generalized robustness still shows entanglement, but with the entanglement witness proposed here with a better performance.

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J. G. Filgueiras, T. O. Maciel, R. E. Auccaise, R. O. Vianna, R. S. Sarthour, I. S. Oliveira. 2012-02-01. Experimental implementation of a NMR entanglement witness. https://doi.org/10.1007/s11128-011-0341-z

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