Correlation between entanglement and spin density in nitrogen-vacancy center of diamond M. Babamoradi, M. Heidari Saani, A. Ranjbar, M.A. Vesaghi and Y. Kawazoe Eur. Phys. J. D, 65 3 (2011) 597-603 Published online: 01 December 2011 DOI: 10.1140/epjd/e2011-20335-5