RT Journal Article
T1 Superadditivity of Private Information for Any Number of Uses of the Channel
A1 Elkouss, David
A1 Strelchuk, Sergii
AB The quantum capacity of a quantum channel is always smaller than the capacity of the channel for private communication. Both quantities are given by the infinite regularization of the coherent and the private information, respectively, which makes their evaluation very difficult. Here, we construct a family of channels for which the private and coherent information can remain strictly superadditive for unbounded number of uses, thus demonstrating that the regularization is necessary. We prove this by showing that the coherent information is strictly larger than the private information of a smaller number of uses of the channel. This implies that even though the quantum capacity is upper bounded by the private capacity, the nonregularized quantities can be interleaved.
PB American Physical Society
SN 0031-9007
YR 2015
FD 2015-07
LK https://hdl.handle.net/20.500.14352/24155
UL https://hdl.handle.net/20.500.14352/24155
LA eng
NO Ministerio de Economía y Competitividad (MINECO)
NO Comunidad de Madrid
NO European Union
NO European CHISTERA project CQC
NO John Templeton Foundation
DS Docta Complutense
RD 9 abr 2025