Non-interactive Information Reconciliation for Quantum Key Distribution

Quantum key distribution (QKD) is an emerging technology that provides provable security for point-to-point connections. Its security lies in the fragility of its information carriers, being photons rather than electromagnetic waves. Freespace QKD is particularly interesting, because building optical free-space quantum networks possibly circumvents environmental obstacles that the designers of a cable-based network would have faced. The logical divide of channels in QKD calls for novel models that capture distortions of photon transmission, as the security vitally relies on precise error estimation. We present a model for the quantum channel and discuss channel coding for QKD in optical networks. Our model employs no assumptions whatsoever on the QKD protocol itself, apart from it utilizing photon transmissions. Many QKD implementations meet that requirement. In particular, we prove the unexpected fact that higher transmission rates facilitate non-interactive error correction, thus reducing the communication overhead and increasing the output key-rate. Our theoretical model assumptions are supported by experimental results, confirming the non-Gaussian flavor of noise in some quantum channels.