title: Directional coupling for quantum computing and communication.
abstract: We introduce the concept of directional coupling, i.e., the selective transfer of a state between adjacent quantum wires, in the context of quantum computing and communication. Our analysis rests upon a mathematical analogy between a dual-channel directional coupler and a composite spin system.
authors.affiliation: Institute of Electronic Structure and Laser, FORTH, P.O. Box 1527, Heraklion 711 10, Crete, Greece.
authors.forename: Georgios M
authors.initials: GM
authors.lastname: Nikolopoulos