  We analyze the entropy production and the maximal extractable work from a
squeezed thermal reservoir. The nonequilibrium quantum nature of the reservoir
induces an entropy transfer with a coherent contribution while modifying its
thermal part, allowing work extraction from a single reservoir, as well as
great improvements in power and efficiency for quantum heat engines.
Introducing a modified quantum Otto cycle, our approach fully characterizes
operational regimes forbidden in the standard case, such as refrigeration and
work extraction at the same time, accompanied by efficiencies equal to unity.
