Quantum-Dot-Based Telecommunication-Wavelength Quantum Relay

Optical quantum-communication networks require the development of practical technology, particularly sources of entangled photon pairs, to mitigate the impact of photon loss on error rates in long-distance transmission. Sources generally do not operate at telecom wavelengths, are incompatible with existing fiber networks, or suffer from classical photon statistics---a potential threat to security. By using a semiconductor quantum dot, the authors demonstrate a quantum relay that is compatible with standard telecom infrastructure and at the same time intrinsically secure.