title: Purely quantum superadditivity of classical capacities of quantum multiple access channels.
abstract: We are studying classical capacities of quantum memoryless multiaccess channels in geometric terms and we are revealing a break of additivity of the Holevo-like capacity. This effect is a purely quantum mechanical one, since, as we point out, the capacity regions of all classical memoryless multiaccess channels are additive. It is the first such effect revealed in the field of classical information transmission via quantum channels.
authors.affiliation: Faculty of Applied Physics and Mathematics, Gdansk University of Technology, Gdansk, Poland. lczekaj@mif.pg.gda.pl
authors.forename: Lukasz
authors.initials: L
authors.lastname: Czekaj
authors.forename: Pawel
authors.initials: P
authors.lastname: Horodecki