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arXiv · 2503.11239

Optical-pumping attack on a quantum key distribution laser source

Maxim Fadeev·Anastasiya Ponosova·Qingquan Peng·Anqi Huang·Roman Shakhovoy·Vadim Makarov
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Abstract

We report a new type of vulnerability in practical implementations of quantum key distribution systems. We show that it is possible to increase the pulse energy of a source laser diode not only by injection-locking it by external light near its emission wavelength of 1550 nm, but also by optically pumping it at a much shorter wavelength. We demonstrate 10% increase in pulse energy when exposing the laser diode to 1310-nm, 1.6-mW cw laser light via its fiber pigtail. This may allow an eavesdropper to steal the secret key. A possible countermeasure is to install broadband optical filters and isolators at the source's output and characterise them during the security certification.

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Maxim Fadeev, Anastasiya Ponosova, Qingquan Peng, Anqi Huang, Roman Shakhovoy, Vadim Makarov. 2025-03-14. Optical-pumping attack on a quantum key distribution laser source. https://doi.org/10.1364/oe.562406

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