  We present a quantum Otto engine model consisting of two isochoric and two
adiabatic strokes, where the adiabatic expansion or compression is realized by
adiabatically changing the shape of the potential. Here we show that such an
adiabatic deformation may alter operation mode and enhance machine performance
by increasing output work and efficiency, even with the advantage of decreasing
work fluctuations. If the heat engine operates under maximal power by
optimizing the control parameter, the efficiency shows certain universal
behavior.
