Timing and synchronisation for high‐loss free‐space quantum communication with Hybrid de Bruijn Codes

Peide Zhang, Daniel K. L. Oi, David Lowndes, John G. Rarity

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Satellite-based long distance free space quantum key distribution has the potential to realize global quantum secure communication networks. Detecting faint quantum optical pulses sent from space requires highly accurate and robust classical timing systems to pick out signals from the noise and allow for reconciliation of sent and received key bits. For such high loss applications, we propose a fault-tolerant synchronisation signal coding and decoding scheme based on de Bruijn sequences. A representative synchronisation timing system was tested in laboratory conditions and demonstrated high fault tolerance for the error correction algorithm even under high loss. We also discuss performance limitations of this solution, analyse the maximum error-tolerance of the scheme and the estimated computational overhead, allowing for the possibility of implementation on a real-time system-on-chip. This solution not only can be used for synchronisation of high-loss channels such as between satellites and ground stations, but can also be extended to applications with low loss, high bit error rate, but requiring reliable synchronisation such as quantum and non-quantum communications over terrestrial free space or fibre optic channels.
Original languageEnglish
Pages (from-to)80-89
Number of pages10
JournalIET Quantum Communication
Issue number3
Early online date19 Aug 2021
Publication statusPublished - 19 Aug 2021


  • quantum communication
  • timing synchronisation
  • coding system


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