Optical channels, such as fibers or free-space links, are ubiquitous in today's telecommunication networks. A complete physical model of these channels must necessarily take quantum effects into account in order to determine their ultimate performances. Specifically, Gaussian bosonic quantum channels have been extensively studied over the past decades given their importance for practical purposes. In spite of this, a longstanding conjecture on the optimality of Gaussian encodings has yet prevented finding their communication capacity. In this talk we will present a recent result that solves this conjecture and establishes the ultimate achievable bit rate under an energy constraint. We will conclude discussing further implications of our result.
Joint work with V. Giovannetti, N. J. Cerf and A. S. Holevo
(PLEASE NOTE NON-STANDARD LOCATION)