  Switching controlled dynamics allows for fast, flexible control design
methods for quantum stabilization of pure states and subspaces, which naturally
include both Hamiltonian and dissipative control actions. A novel approach to
measurement-based, dissipative feedback design is introduced, and extends the
applicability of switching techniques with respect to previously proposed ones,
as it does not need stringent invariance assumptions, while it still avoids
undesired chattering or Zeno effects by modulating the control intensity. When
the switching dynamics do leave the target invariant, on the other hand, we
show that exponential convergence to the target can be enforced without
modulation, and switching times that can be either fixed or stochastic with
hysteresis to avoid chattering. The effectiveness of the proposed methods is
illustrated via numerical simulations of simple yet paradigmatic examples,
demonstrating how switching strategies converge faster than open-loop
engineered dissipation.
