Quantum information technology: Theory and applications

In the last decade quantum information theory and technology evolve and show their great potential. There are a set of problems for which it's more efficient and even not possible with classical communication to solve than with quantum equivalent. The best known example is Quantum Key Distribution, though there are quantum non-locality (entanglement), quantum teleportation, communication complexity and many more. Quantum communication relies on some phenomenon like entanglement which gives plenty of opportunities, but at the same time it's very tricky. Present knowledge lets us define entanglement as a property of quantum system when two or more objects are linked together (quantum states).