  Probabilistic quantum filtering is proposed to properly adapt sequential
independent quantum channels in order to stop sudden death of entanglement. In
the adaptation, the quantum filtering does not distill or purify more
entanglement, it rather properly prepares entangled state to the subsequent
quantum channel. For example, the quantum adaptation probabilistically
eliminates the sudden death of entanglement of two-qubit entangled state with
isotropic noise injected into separate amplitude damping channels. The result
has a direct application in quantum key distribution through noisy channels.
