Quantum adaptation of noisy channels

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 an entangled state to the subsequent quantum channel. In particular, the quantum adaptation probabilistically eliminates the sudden death of entanglement of a two-qubit entangled state with isotropic noise injected into separate amplitude damping channels. The result has an application in quantum key distribution through noisy channels.