Gaussian Entanglement for Quantum Key Distribution from a Single-Mode   Squeezing Source
  We report the suitability of an Einstein-Podolsky-Rosen (EPR) entanglement source for gaussian continuous-variable quantum key distribution at 1550 nm. Our source is based on a single continuous-wave squeezed vacuum mode combined with a vacuum mode at a balanced beam splitter. Extending a recent security proof, we characterize the source by quantifying the extractable length of a composable secure key from a finite number of samples under the assumption of collective attacks. We show that distances in the order of 10 km are achievable with this source for a reasonable sample size despite the fact that the entanglement was generated including a vacuum mode. Our security analysis applies to all states having an asymmetry in the field quadrature variances, including those generated by superposition of two squeezed modes with different squeezing strengths. 
Tobias Eberle, Vitus H\"andchen, J\"org Duhme, Torsten Franz, Fabian   Furrer, Roman Schnabel, Reinhard F. Werner
quant-ph