We demonstrate that secure quantum key distribution systems based on
continuous variables implementations can operate beyond the apparent 3 dB loss
limit that is implied by the beam splitting attack . The loss limit was
established for standard minimum uncertainty states such as coherent states. We
show that by an appropriate postselection mechanism we can enter a region where
Eve's knowledge falls behind the information shared between Alice and Bob even
in the presence of substantial losses.Comment: 4 pages, 2 figure
