  We show that a quantum Otto cycle in which the medium, an interacting
ultracold gas, is driven between a superfluid and an insulating phase can
outperform similar single particle cycles. The presence of an energy gap
between the two phases can be used to improve performance, while the interplay
between lattice forces and the particle distribution can lead to a many-body
cooperative effect. Since finite time driving of this cycle can create unwanted
non-equilibrium dynamics which can significantly impair the performance of the
engine cycle, we also design an approximate shortcut to adiabaticity for the
many-body state that can be used to achieve an efficient Otto cycle around a
critical point.
