Deployed entanglement-based BBM92 quantum key distribution using frequency-converted photons emitted by a quantum dot
Abstract
Establishing secure communication is an important requirement in existing and future networks. Although current solutions rely on classical approaches, quantum mechanics offers the possibility of moving from computational to information-theoretic security. Quantum key distribution (QKD) has been extensively studied as a means of achieving such security. Recently, epitaxial quantum dots started to be studied and employed in quantum cryptography, because of their rapid development that made them one of the brightest sources of quantum light to date. In particular, they are known to be excellent sources of polarization-entangled photon pairs, especially droplet-etched dots operating at ∼780 nm. Here, we employ such a quantum dot to generate entangled photon pairs under 1 GHz excitation rate. Using quantum frequency conversion, we interface the emitted photons with the telecommunication wavelength range while preserving their polarization entanglement. This enables quantum key distribution over a 1.59 km field-deployed fibre link across the University of Stuttgart - campus Vaihingen, using the BBM92 protocol: we achieve a secure key rate of 206 Hz over 19 h of stable operation, resulting in a total secure key length of 14.2 Mbit. This key enables the safe encryption and decryption of a colour image with further implementation of error correction and privacy amplification. These results demonstrate important steps towards hybrid quantum networks by combining high-quality entangled-photon sources operated at high excitation rates, efficient frequency conversion module, and picosecond-level time synchronization in a realistic deployed network.
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BibTeX
@misc{vyvlecka2026deployed,
title = {{Deployed entanglement-based BBM92 quantum key distribution using frequency-converted photons emitted by a quantum dot}},
author = {Michal Vyvlecka and Raphael Joos and Benjamin Breiholz and Emma Marmasse and Ilenia Neureuther and Timo Schnieber and Anna Frederike Köhler and Tim Strobel and Andreas Berg and Sebastian Kiesel and Tobias Bauer and Marlon Schäfer and Nand Lal Sharma and Caspar Hopfmann and Simone Luca Portalupi and Christoph Becher and Peter Michler},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37268},
eprint = {2610.37268},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37268},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Deployed entanglement-based BBM92 quantum key distribution using frequency-converted photons emitted by a quantum dot
AU - Michal Vyvlecka
AU - Raphael Joos
AU - Benjamin Breiholz
AU - Emma Marmasse
AU - Ilenia Neureuther
AU - Timo Schnieber
AU - Anna Frederike Köhler
AU - Tim Strobel
AU - Andreas Berg
AU - Sebastian Kiesel
AU - Tobias Bauer
AU - Marlon Schäfer
AU - Nand Lal Sharma
AU - Caspar Hopfmann
AU - Simone Luca Portalupi
AU - Christoph Becher
AU - Peter Michler
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37268
UR - https://arxiv.org/abs/2610.37268
AB - Establishing secure communication is an important requirement in existing and future networks. Although current solutions rely on classical approaches, quantum mechanics offers the possibility of moving from computational to information-theoretic security. Quantum key distribution (QKD) has been extensively studied as a means of achieving such security. Recently, epitaxial quantum dots started to be studied and employed in quantum cryptography, because of their rapid development that made them one of the brightest sources of quantum light to date. In particular, they are known to be excellent sources of polarization-entangled photon pairs, especially droplet-etched dots operating at ∼780 nm. Here, we employ such a quantum dot to generate entangled photon pairs under 1 GHz excitation rate. Using quantum frequency conversion, we interface the emitted photons with the telecommunication wavelength range while preserving their polarization entanglement. This enables quantum key distribution over a 1.59 km field-deployed fibre link across the University of Stuttgart - campus Vaihingen, using the BBM92 protocol: we achieve a secure key rate of 206 Hz over 19 h of stable operation, resulting in a total secure key length of 14.2 Mbit. This key enables the safe encryption and decryption of a colour image with further implementation of error correction and privacy amplification. These results demonstrate important steps towards hybrid quantum networks by combining high-quality entangled-photon sources operated at high excitation rates, efficient frequency conversion module, and picosecond-level time synchronization in a realistic deployed network.
ER -