Experimental loophole-free violation of a Bell inequality using entangled electron spins separated by 1.3 km
arXiv (2015) - Comments
doi: 1508.05949  arxiv: 1508.05949 

B. Hensen, H. Bernien, A. Dréau, A. Reiserer, N. Kalb, M. Blok, J. Ruitenberg, R. Vermeulen, R. Schouten, C. Abellán, W. Amaya, V. Pruneri, M. Mitchell, M. Markham, D. Twitchen, D. Elkouss, S. Wehner, T. Taminiau, R. Hanson