Quantum confined stark effect in wide parabolic quantum wells: real density matrix approach Sylwia Zielińska-Raczyńska, Gerard Czajkowski and David Ziemkiewicz Eur. Phys. J. B, 88 12 (2015) 338 Published online: 16 December 2015 DOI: 10.1140/epjb/e2015-60623-2