Reducing energy consumption of fiber networks via quantum communication technology

Due to the growing energy consumption of communication infrastructures, energy-efficiency is becoming a primary design constraint in optical-fiber networks. In particular, for long-distance communication, a significant fraction of the energy budget is spent on powering optical amplifiers that counteract the signal's attenuation, as measured by their gain. Here we show that an optimal quantum joint-detection receiver (OJDR) can significantly reduce the energy consumption of amplified optical communication links at any distance. Surprisingly, we find that the communication rate attainable with the OJDR is maximized by decreasing the amplifier gains as a function of their distance from the sender, in contrast with the optimal classical receiver, which requires full amplification. We then minimize the amplification energy cost with respect to the gain profile and observe significant energy savings in practically relevant communication settings, e.g., $\approx$55\% savings for a 2-fold enhancement of the communication rate. Our results mark a drastic change of perspective on classical data transmission via quantum channels, shifting the attention from large gains at small practical usefulness, such as short-distance- or deep-space- communication, to significant gains in a practically relevant regime.