Experimental demonstration of a reconfigurable free-space receiver implementing polarization routing and filtering for daytime quantum key distribution

Alfonso Tello Castillo, Ugo Zanforlin, Gerald Stuart Buller, Ross J. Donaldson

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)
24 Downloads (Pure)

Abstract

Free-space quantum key distribution (QKD) systems are often designed to implement polarization-encoding protocols. Alternatively, time-bin/phase-encoding protocols are considerably more challenging to perform over a channel experiencing atmospheric turbulence. However, over the last decade, new and improved optical platforms have revived the interest in them. In this paper, we present a free-space multi-protocol receiver designed to work with three different time-bin/phase-encoding protocols highlighting its interoperability with different systems and architectures for potential satellite-based communications. We also present a detailed analysis of different experimental configurations when implementing the coherent one-way (COW) protocol in a free-space channel, as well as a polarization filtering technique showing how time-bin/phase-encoding protocols could be used for QKD applications in daylight conditions. We demonstrate secret key rates of several kbps for channels with a total 30 dB attenuation even with moderately high QBERs of ≈3.5%. Moreover, a 2.6 dB improvement in the signal to noise ratio is achieved by filtering background light in the polarization degree of freedom, a technique that could be used in daylight QKD.
Original languageEnglish
Pages (from-to)40317-40327
Number of pages11
JournalOptics Express
Volume31
Issue number24
Early online date14 Nov 2023
DOIs
Publication statusPublished - 20 Nov 2023

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