Quantum Communications [Guest Editorial]

The main goal of quantum communication is to transfer a quantum state between two geographically separated agents. From a practical and simplistic point of view, this problem can be restated as that of sending a single photon with a particular polarization via, say, an optical fiber connecting the agents. The difference between classical and quantum communications follows from the fact that quantum states are ruled by different physical laws; hence, quantum communications exhibits particular properties not found in its classical counterpart.