Tools for the performance optimization of single-photon QKD

BB84-QKD testbed using a triggered solid-state single-photon source (SPS) and polarization coding.

Quantum light sources emitting triggered single photons or entangled photon pairs have the potential to boost the performance of quantum key distribution (QKD) systems. Proof-of-principle experiments affirmed these prospects, but further efforts are necessary to push this field beyond its current status.

A team of researchers at Institut für Festkörperphysik, Germany, has showed that temporal filtering of single-photon pulses enables a performance optimization of QKD systems implemented with realistic quantum light sources, both in experiment and simulations.

To this end, they analyzed the influence of temporal filtering of sub-Poissonian single-photon pulses on the expected secret key fraction, the quantum bit error ratio, and the tolerable channel losses. For this purpose, they developed a basic QKD testbed comprising a triggered solid-state single-photon source and a receiver module designed for four-state polarization coding via the BB84 protocol.

Furthermore, they demonstrated real-time security monitoring by analyzing the photon statistics, in terms of g(2)(0), inside the quantum channel by correlating the photon flux recorded at the four ports of our receiver.

Their findings are useful for the certification of QKD and can be applied and further extended for the optimization of various implementations of quantum communication based on sub-Poissonian quantum light sources, including measurement-device-independent schemes of QKD as well as quantum repeaters.

Their work represents an important contribution towards the development of QKD-secured communication networks based on quantum light sources.

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