  Quantum information processing technology offers several communication
strategies, which offer capacity advantages over classical technologies.
However, advantages typically arise only in very particular communication
scenarios which are of limited use in public networks. Most importantly,
striking capacity advantages have so far been found only for cases where the
system capacity is way below commercially interesting values. In this work we
present a novel scenario where pre-shared entanglement offers arbitrarily high
capacity advantages, and where at the same time data rates are compatible with
future network demand. Our approach rests on the observation that the number of
modes in multi-mode fiber can be increased solely by tuning of the refractive
index, while maintaining the fiber diameter.
