Negentropy as a source of efficiency: a nonequilibrium quantum Otto cycle Hai Li, Jian Zou, Wen-Li Yu, Lin Li, Bao-Ming Xu and Bin Shao Eur. Phys. J. D, 67 7 (2013) 134 Published online: 09 July 2013 DOI: 10.1140/epjd/e2013-30763-8