Operating Fiber Networks in the Quantum Limit

We consider all-optical networks from a quantum perspective. We show that optimal quantum receivers allow a \sim 57% decrease in energy consumption of all-optical amplifiers. Furthermore, we prove that quantum receivers allow for a logarithmic scaling of the system capacity with the number of pulses per second, while standard Shannon-type systems are limited by the transmit power. Based on our findings we argue for a new approach to optical communication network design, wherein in-line amplifiers are operated at very low gains and in conjunction with high-spectral-bandwidth fiber and a quantum receiver, enhancing data transmission in a practically relevant quantum limit.