  We propose a strategy to modulate the decoherence dynamics of a two-level
system, which interacts with a dissipative bosonic environment, by introducing
an assisted degree of freedom. It is revealed that the decay rate of the
two-level system can be significantly suppressed under suitable steers of the
assisted degree of freedom. Our result provides an alternative way to fight
against decoherence and realize a controllable dissipative dynamics.
