UFCG 2

Biblioteca Digital de Teses e Dissertações da UFCG 2

PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIA E SAÚDE ANIMAL 1 PÓS-GRADUAÇÃO EM ENGENHARIA ELÉTRICA 1

MAIA, Amanda Rafaela Alves 1 MEDEIROS, Rex Antonio da Costa 1

ASSIS, Francisco Marcos de. 1 AZEVEDO, Sérgio Santos de. 1

Tese 1 Dissertação 1

Bovine cysticercosis - Paraíba 1 Bovinos - cisticercose 1 Canais Quânticos 1 Canal Quântico Ruidoso 1 Capacidade Erro-Zero de Canais Quânticos - CEZQ 1 Cattle - cysticercosis 1 Mais ... Cisticercose bovina - Paraíba 1 Diagnóstico sorológico - cisticercose 1 Epidemiologia Veterinária 1 Erro-Zero de Canais Discretos 1 Erro-Zero de Canais Quânticos 1 Estado da Paraíba - cisticercose bovina 1 Estudo epidemiológico espacial 1 Protocolo de Holevo-Schumacher-Westmoreland 1 Quantum Channels 1 Serological diagnosis - cysticercosis 1 Serology 1 Sorologia 1 Spatial epidemiological study 1 State of Paraíba - bovine cysticercosis 1 Telecomunicações 1 Veterinary Epidemiology 1 Ver todos ... menos ...

Engenharia Elétrica. 1 In this thesis, we generalise Shannon’s zero-error capacity of discrete memoryless channels to quantum channels. We propose a new kind of capacity for transmitting classical information through a quantum channel. The quantum zero-error capacity (QZEC) is defined as being 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 restricts codewords to tensor products of input quantum states, whereas collective measurements can be performed between several channel outputs. Hence, our communication protocol is similar to the Holevo-Schumacher-Westmoreland protocol. We reformulate the problem of finding the QZEC in terms of graph theory. This equivalent definition allows us to demonstrate some properties of ensembles of quantum states and measurements attaining the QZEC. We show that the capacity of ad-dimensional quantum channel can always be achieved by using an ensemble of at mostd pure quantum states, and collective von Neumann measurements are necessary and sufficient to attain the channel capacity. We discuss whether the QZEC is a non-trivial generalisation of the classical zero-error capacity. By non-trivial we mean that there exist quantum channels requiring two or more channel uses in order to reach the capacity, and the capacity can only be attained by using ensembles of non-orthogonal quantum states at the channel input. We also calculate the QZEC of some quantum channels. We show that finding the QZEC of classical-quantum channels is a purely classical problem. In particular, we exhibit a quantum channel for which we claim the QZEC can only be reached by a set of non-orthogonal states. If the conjecture holds, it is possible to give an exact solution for the capacity, and construct an error-free quantum block code reaching the capacity. Finally, we demonstrate that the QZEC is upper bounded by the Holevo-Schumacher-Westmoreland capacity. 1 Medicina Veterinária 1