Experimental implementation of a NMR entanglement witness
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.
Keywords
Cite
@article{arxiv.1202.0235,
title = {Experimental implementation of a NMR entanglement witness},
author = {J. G. Filgueiras and T. O. Maciel and R. E. Auccaise and R. O. Vianna and R. S. Sarthour and I. S. Oliveira},
journal= {arXiv preprint arXiv:1202.0235},
year = {2012}
}