Using quantum technologies to improve fiber optic communication systems

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.

Introduction

Quantum physics theory was developed in the first few decades of the 20th century in an endeavor to understand the fundamental properties of matter and its interaction with electromagnetic radiation. Despite quantum theory's ability to predict the results of some of the more intriguing experiments of the time, some of the peculiarities of the theory (e.g., Heisenberg's uncertainty principle or the existence of entangled states) caused serious skepticism in the scientific community. There-fore, it came as no surprise that the first efforts and developments were carried out envisioning validation of the theoretical predictions rather than looking for practical appli-cations. These efforts gave the theory very solid foundations, and quantum theory is now widely accepted as a complete and accurate physical theory.