High-Speed Large-Alphabet Quantum Key Distribution Using Photonic Integrated Circuits
Final rept. 25 Aug 2010-25 Oct 2013
COLUMBIA UNIV NEW YORK
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This program theoretically and experimentally investigated the private information capacity of optical channels under experimental constraints. Theoretical work established upper and lower bounds on the Holevo secrecy capacity for optical channels, including channels in turbulent atmosphere, and developed the coding and modulation techniques to approach the maximum key distribution rate over optical channels, in the regime of simultaneously high photon and bandwidth efficiencies. The program also developed two quantum key distribution QKD protocols that achieve an information capacity of multiple secure bits per photon pair, providing the first security proofs for experimentally realizable high-dimensional QKD schemes against collective attacks. These protocols represent quantum secure versions of pulse-position- modulation schemes that are commonly employed in energy-constrained electromagnetic channels. Novel adaptive pulseposition modulation and layered coding schemes provide efficient error correction. The experimental effort developed QKD hardware in silicon photonic integrated circuits PIC, including waveguide-integrated superconducting nanowire single photon detectors. Ultra-bright waveguide-based entangled pair generation was demonstrated with record high entanglement purity measured using dispersion-compensated Franson interferometry. QKD systems were demonstrated with secure key generation in excess of 6 Mbitsecond and a photon efficiency in excess of 3 secure bits per detected photon.
- Non-Radio Communications