Universal evolution of non-classical correlations due to collective spontaneous emission A. Slaoui, M. I. Shaukat, M. Daoud and R. Ahl Laamara Eur. Phys. J. Plus, 133 10 (2018) 413 Published online: 12 October 2018 DOI: 10.1140/epjp/i2018-12211-y