R. M. Wilson, Mahmud, K. W., Hu, A., Gorshkov, A. V., Hafezi, M., and Foss-Feig, M.,
“Collective phases of strongly interacting cavity photons”,
Physical Review A, vol. 94, no. 3, p. 033801, 2016.
J. Chen, Ji, Z., Ruskai, M. Beth, Zeng, B., and Zhou, D. - L.,
“Comment on some results of Erdahl and the convex structure of reduced density matrices”,
Journal of Mathematical Physics, vol. 53, no. 7, p. 072203, 2012.