Negentropy as a source of efficiency: a nonequilibrium quantum Otto cycleHai Li, Jian Zou, Wen-Li Yu, Lin Li, Bao-Ming Xu and Bin ShaoEur. Phys. J. D, 67 7 (2013) 134DOI: https://doi.org/10.1140/epjd/e2013-30763-8