Towards polarisation-encoded quantum key distribution in optical fibre networks

  • Sharmini Pillay Quantum Research Group, School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa
  • Abdul R. Mirza 1 Quantum Research Group, School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa 2 QZN Technology – Innovation Centre, University of KwaZuluNatal, Durban, South Africa
  • Francesco Petruccione 1 Quantum Research Group, School of Chemistry and Physics, University of KwaZulu-Natal, Durban, South Africa 2 QZN Technology – Innovation Centre, University of KwaZuluNatal, Durban, South Africa 3 National Institute for Theoretical Physics, Durban, South Africa
Keywords: QKD, cryptography, polarisation encoding, fibre network, single photon

Abstract

Quantum key distribution – a process that encodes digital information – often utilises fibre optic technologies for commercial applications. Fibre provides the benefit of a dark channel as well as the convenience of independence of a line-of-sight connection between the sender and receiver. In order to implement quantum key distribution protocols utilising polarisation encoding, the birefringence effects of fibre must be compensated for. Birefringence is caused by manufacturing impurities in the fibre or a change in environmental conditions and results in a rotation of the state of polarisation of light as it is propagated through the fibre. With dynamic environmental conditions, the birefringence effects should be monitored with a test signal at regular time intervals so that the polarisation of each photon can be appropriately compensated to its original state. Orthogonal states are compensated simultaneously, but most protocols, such as BB84 and B92, require non-orthogonal basis sets. Instead of using a compensator for each basis, the presented scheme fixes the polarisation controller onto the plane on the Poincaré that passes through both bases, compensating both non-orthogonal bases simultaneously.

Views
  • Abstract 66
  • PDF 131
  • EPUB 32
  • XML 66
Views and downloads are with effect from 11 January 2018
Published
2015-07-27