Quasi-superradiant soliton state of matter in quantum metamaterials Hidehiro Asai, Shiro Kawabata, Sergey E. Savel’ev and Alexandre M. Zagoskin Eur. Phys. J. B, 91 2 (2018) 30 Published online: 07 February 2018 DOI: 10.1140/epjb/e2017-80567-7