Seminário de Computação e Informação Quântica 

05/02/2010, 15:00 — 16:00 — Sala P4.35, Pavilhão de Matemática
Francisco Marcos de Assis, U Federal de Campina Grande

Zero-Error Capacity of a Quantum Channel

Quantum channels have a number of capacities that depends fundamentally on the kind of information to be carried, the employed resources and the communication protocol. In this work, we generalize the definition of zero-error capacity of a classical channel to the zero-error capacity of a quantum channel. We propose a new kind of capacity for transmitting classical information through a quantum channel.

The quantum zero-error capacity is defined by the maximum amount of classical information per channel use that can be sent over a noisy quantum channel, with the restriction that the probability of error must be equal to zero. The communication protocol used in the definition assumes codewords are built as tensor products of input quantum states, whereas entangled measurements can be performed between several channel outputs. Hence, our communication protocol is similar to the Holevo-Schumacher-Westmoreland protocol. Additionally we introduce some connection between concepts related to quantum channel capacity with concepts found in graph theory.