Complete contraction and expansion conjecture for amplitude damping channels
Let denote the amplitude damping channel with damping parameter , and for two channels define the complete contraction and expansion coefficients by
where the optimization ranges over all valid states on . Complete contraction and expansion conjecture. If , then
This is proposed as a sufficient condition for positivity of the ratio for the pair of amplitude damping channels; its resolution is not established in the supplied text.
References
Primary source
Graeme Smith and Peixue Wu, “Additivity of quantum capacities in simple non-degradable quantum channels”, arXiv:2409.03927 (2025).
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