The effect of quantum noise on the energy degeneration in a dissipative quantum two-level system

The influence of noise on the energy degeneration in a periodically driven two-state system is discussed. It is shown that the degenerate energy level of the system, split by an external monochromatic field, can be restored to the degenerate state by appropriate noise. In addition, the maximum oscillation amplitude at a series of values of the temperature in the deep tunneling regime exhibit the phenomenon of quantum multiple stochastic resonance.