We describe a continuous-variable coherent-states quantum-key distribution system working at $1550\mathrm{nm}$, and entirely made of standard fiber optics and telecommunications components, such as integrated-optics modulators, couplers and fast InGaAs photodiodes. The setup is composed of an emitter randomly modulating a coherent state in the complex plane with a doubly Gaussian distribution, and a receiver based on a shot-noise limited time-resolved homodyne detector. By using a reverse reconciliation protocol, the device can transfer a raw key rate up to $1\mathrm{Mbit}∕\mathrm{s}$, with a proven security against Gaussian or non-Gaussian attacks. The dependence of the secret information rate of the present fiber setup is studied as a function of the line transmission and excess noise.

• Received 13 July 2005

DOI:https://doi.org/10.1103/PhysRevA.72.050303