Enhancing the efficiency of quantum measurement-based engines with entangling measurements

We study the impact of entangling measurements on the efficiency of quantum measurement-based engines. We first demonstrate that for engines comprising many subsystems the efficiency can be enhanced through the implementation of entangling measurements. Then, we show that when the collective measurement yields the same local state for the subsystems as individual local measurements, the improvement is directly proportional to the amount of correlations among the subsystems. Finally, we present examples for two-level systems where this type of engine can operate at perfect efficiency yielding a finite amount of work in the limit of a large number of subsystems; we also discuss how to generalize this idea to larger systems.