Contributed Talks 5b: QKD implementation (Chair: Rupesh Kumar)

contributed

Fri, 27 Aug , 11:45 - 12:15

Coexistence of a Quantum QKD Channel and 4×100 Gbps Classical Channels in Nested Antiresonant Nodeless Hollow Core Fibre

Obada Alia (High performance networking group / University of Bristol); Rodrigo Stange Tessinari (High performance networking group / University of Bristol); Thomas Bradley (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Hesham Sakr (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Kerrianne Harrington (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); John Hayes (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Yong Chen (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Periklis Petropoulos (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); George Kanellos (High performance networking group / University of Bristol); David Richardson (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Francesco Poletti (Optoelectronics Research Centre, University of Southampton, Southampton SO17 1BJ, UK); Reza Najebati (High performance networking group / University of Bristol); Dimitra simidunio (High performance networking group / University of Bristol)

[abstract]
Abstract: We demonstrated for the first time a coexistence between a quantum QKD channel and 4×100 Gbps pm-qpsk carrier-grade classical optical channels in a 2 km Nested Antiresonant Nodeless Hollow Core fibre. Our results show a drop of less than 10% in the Secret Key Rate (SKR) when using a HCF compared to a significant drop of 97% in the SKR when quantum and classical signals coexist on a single core of a Multicore fibre (MCF) with equal losses, indicating that NANF type HCF significantly outperforms single-mode fibres (SMF) performance for quantum/classical coexistence. This significant difference in the SKR drop is due to the ultra-low nonlinear effects in HCF comparing to glass core fibres such as SMF and MCF.

[YouTube, presented by Obada Alia and Fadri Grünenfelder]

Presenter live session: Obada Alia

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The limits of multiplexing of quantum and classical channels: Case study of a 2.5 GHz discrete variable QKD system

Fadri Grünenfelder (University of Geneva); Rebecka Sax (University of Geneva); Alberto Boaron (University of Geneva); Hugo Zbinden (University of Geneva)

[abstract]
Abstract: To enable the widespread use of Quantum Key distribution, network integration is crucial. We present a case study where we investigate the performance of a 2.5 GHz simplified BB84 implementation using a wavelength of 1310nm multiplexed in a fiber together with 13 classical channels. We found that a secret key exchange at a distance of 95.5km and classical launch power up to 8.9dBm was possible. Further, we compare our results to previous results, both for continuous variable systems using a wavelength of 1550nm and discrete variable systems using either a wavelength of 1550nm or 1310nm. We find that both for long distance and for high power in the classical channels, the discrete variable systems perform better.

Presenter live session: Fadri Grünenfelder
Minimizing detection losses from time-bin quantum cryptography systems with few-mode fibre technology

Alvaro Alarcon (Linköping University); Joakim Argillander (Linköping University); Gustavo Lima (University of Concepcion); Guilherme Xavier (Linköping University)

[abstract]
Abstract: Time-bin quantum cryptography systems have a fundamental post-selection loss at the detection stage, which increases with the dimension and that limits its application over long distances. Here, we are able to solve this long-standing hurdle by employing a few-mode fibre space-division multiplexing platform working with orbital angular momentum modes. In our scheme, we maintain the practicability provided by the time-bin scheme, while the quantum states are transmitted through a few-mode fibre in a configuration that does not introduce post-selection losses. We experimentally demonstrate our proposal by successfully transmitting phase-encoded single-photon states for quantum cryptography over 500 m of few-mode fibre, thus opening up new paths for quantum communication systems.

[arXiv: 2103.05018]

[YouTube, presented by Guilherme Xavier]

[slides]

Presenter live session: Alvaro Alarcon
Finite key effects in satellite quantum key distribution

Jasminder S. Sidhu (University of Strathclyde); Thomas Brougham (University of Strathclyde); Duncan McArthur (University of Strathclyde); Roberto G. Pousa (University of Strathclyde); Daniel K. L. Oi (University of Strathclyde)

[abstract]
Abstract: Global quantum communications will enable long-distance secure data transfer, networked distributed quantum information processing, and other entanglement-enabled technologies. Satellite quantum communication overcomes optical fibre range limitations, with the first realisations of satellite quantum key distribution (SatQKD) being rapidly developed. However, limited transmission times between satellite and ground station severely constrains the amount of secret key due to finite-block size effects. Here, we analyse these effects and the implications for system design and operation, utilising published results from the Micius satellite to construct an empirically-derived channel and system model for a trusted-node downlink employing efficient BB84 weak coherent pulse decoy states with optimised parameters. We quantify practical SatQKD performance limits and examine the effects of link efficiency, background light, source quality, and overpass geometries to estimate long-term key generation capacity. Our results provide a guide to the design and analysis of future SatQKD missions, and establishes performance benchmarks for both sources and detectors.

[arXiv: 2012.07829v2]

[YouTube, presented by Jasminder Sidhu]

[slides]

Presenter live session: Jasminder Sidhu