Quantum communications: explained for communication engineers

Moore¿s Law dictates that during the forthcoming decades, new communications and computing technologies that exploit quantum mechanics will become generally available. To assist Communications Society members with this transition, we provide a pragmatic description of quantum communications theory that introduces the quantum mechanical properties of polarization and entanglement, which do not have analogs in classical communications theory. We show plausible examples of how these quantum properties may be exploited to create noisefree channels and to improve channel utilization for distributed MAC protocols. Finally, we describe how entanglement is used to enhance security and improve key distribution efficiency in symmetric-key cryptography systems used by operational quantum cryptographic networks.