We discuss the near future impact that recent developments of quantum technologies can have in the field of fiber optic communication systems. The ability to generate, manipulate, transmit, and detect a single or very few photon(s) may open new routes that can trigger a completely new generation of communication systems. We show that quantum technologies can address two of the more challenging problems communication engineers face nowadays: capacity and security. Indeed, by radically decreasing the number of photons used to encode each bit of information, we can more efficiently explore the full capacity to carry information of optical fibers. Moreover, by encoding information in individual or very few photons, we can take advantage of the quantum laws to add new functionalities to communication systems. Secrecy is the more obvious one, but a completely new set of functionalities can be added at the physical layer considering the peculiarities of quantum laws that rule transmission and detection.