Partially smoothed information measures

Understand

Smooth entropies are a tool for quantifying resource trade-offs in (quantum) information theory and cryptography.

• In typical bi- and multi-partite problems, however, some of the sub-systems are often left unchanged and this is not reflected by the standard smoothing of information measures over a ball of close states.
• We propose to smooth instead only over a ball of close states which also have some of the reduced states on the relevant sub-systems fixed.
• This partial smoothing of information measures naturally allows to give more refined characterizations of various information-theoretic problems in the one-shot setting.