  The influence of the dynamical Stark shift on the thermal entanglement and
the efficiency of the quantum Otto cycle is studied for the su(1,1)
Tavis-Cummings system. It is shown that the degree of the thermal entanglement
becomes larger as the dynamical Stark shift increases. In contrast, the
efficiency of the Otto cycle is degraded with an increase of the values of
dynamical Stark shift. Expressions for the efficiency coefficient are derived.
Using those expressions we identify the maximal efficiency of the quantum Otto
cycle from the experimentally measured values of the dynamical Stark shift
