Effects of Detunings on Dynamically Induced Irreversibility in Coherently Driven Systems

Effects of detunings on dynamically induced irreversibility is studied for coherently driven V systems in which there is no conventional source of irreversible population pumping. For atomic barium (γ₁/γ₂= 400 >> 1, where γ₁ and γ₂ are the rates of the spontaneous decay from the excited states 6s6p¹P₁ and 6s6p³P₁ to the ground state 6s^{2 1}S₀, respectively), the strong irreversibility is found to lead to a maximum inversion of 0.77 only 0.1 in Phys. Rev. Lett. 71 (1993) 4311. The maximum population inversion requires relatively strong fields coupled respectively to two transitions, a disparity in two atomic decay rates, and the atom-field detunings of opposite signs. However, it is also shown that even in the cases where two detunings have the same sign, or where two decay rates are equal, population inversion takes place.