  The quantum ratchet current is studied in the parameter space of the
dissipative kicked rotor model coupled to a zero temperature quantum
environment. We show that vacuum fluctuations blur the generic isoperiodic
stable structures found in the classical case. Such structures tend to survive
when a measure of statistical dependence between the quantum and classical
currents are displayed in the parameter space. In addition, we show that
quantum fluctuations can be used to overcome transport barriers in the phase
space. Related quantum ratchet current activation regions are spotted in the
parameter space. Results are discussed {based on quantum, semiclassical and
classical calculations. While the semiclassical dynamics involves vacuum
fluctuations, the classical map is driven by thermal noise.
