Lossless Quantum Data Compression and Secure Direct Communication- New concepts and methods for quantum information theory

Quantum mechanics has radically changed our classical conception ofinformation and communication. The elementary unit of information thebit is replaced by the qubit which is a superposition of zero and one.Several qubits can be entangled among each other so that each qubit alone isneither zero nor one nor any superposition of it. If qubits are used to encodemessages then these quantum messages do not behave like ordinary ones.They cannot be compressed without loss of information and the process ofreading disturbs their content. Such apparent weaknesses however give riseto a revolutionary concept of secure communication... This book reviews thebasic concepts of quantum information develops a theoretical framework forvariable-length quantum messages derives some theorems and introduces anovel secure communication scheme the so-called Ping-Pong protocolwhich has attracted some interest in the scientific community and hasrecently been experimentally realized. The reader should be roughly familiarwith probability theory linear algebra and basic quantum mechanics.