Quantum modeling of two-level photovoltaic systems Tahereh Nemati Aram, Asghar Asgari, Matthias Ernzerhof, Pascal Quémerais and Didier Mayou EPJ Photovolt., 8 (2017) 85503 Published online: 16 June 2017 DOI: 10.1051/epjpv/2017004