Improving the maximum transmission distance of continuous-variable quantum key distribution using a noiseless amplifier
Rémi Blandino, Anthony Leverrier, Marco Barbieri, Jean Etesse, Philippe Grangier, Rosa Tualle-Brouri · Physical Review A · 2012
We show that the maximum transmission distance of continuous-variable quantum key distribution in presence of a Gaussian noisy lossy channel can be arbitrarily increased using a heralded noiseless linear amplifier. We explicitly consider a protocol using amplitude- and phase-modulated coherent states with reverse reconciliation. Assuming that the secret key rate drops to zero for a line transmittance ${T}_{\mathrm{lim}}$, we find that a noiseless amplifier with amplitude gain $g$ can improve this value to ${T}_{\mathrm{lim}}/{g}^{2}$, corresponding to an increase in distance proportional to $\mathrm{log}g$.