Ebook: Quantum computation and quantum communication: theory and experiments

Mladen Pavicic presents the main elements of the quantum computation and communication theories and their implementation in a self-consistent way that keeps the reader from getting lost in details. The book is not a textbook, does not contain exercises, and can be read without a copybook. It introduces concepts like quantum computer circuits, physical computing, qubit formalism, quantum Turing machine, quantum cryptography, and quantum error correction by means of elementary quantum mechanical formalism and elements of classical computation theory. The concepts that do not have classical counterparts, like quantum entanglement, teleportation, and the no-cloning theorem are introduced with the help of the corresponding experiments. Yet, the presentation does not stop short of discussing some challenging points: The classical Turing machine is a mathematical procedure that singles out the binary Boolean algebra for classical computers. Can the quantum Turing machine provide us with a quantum algebra for quantum computers? The qubit is a two-level system. What are the details of its three-dimensional representation on and in the Bloch sphere? Quantum circuits trace the histories of each qubit and their mutual control-target relationships. How do we handle entangled qubits that share the same state? Shor's algorithm for factoring numbers in a polynomial time is considered one of the most important boosts to the development of quantum computing since the security of today's e-business depends on the assumed exponential classical complexity of factoring numbers. Has quantum cryptography eliminated the need of implementing Shor's algorithm? Would-be super-fast quantum computers can beuniversal simulators of quantum systems. Can they also be universal computers?