Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum 2.0 Conference and Exhibition

Quantum network operations over the Saarbrücken telecom fiber link

Christian Haen, Stephan Kucera, Elena Arenskötter, Jonas Meiers, Tobias Bauer, Christoph Becher, Jürgen Eschner

Published Jan 1, 2024• 1 citation
Publisher

Abstract

We report on the implementation of quantum entanglement distribution and quantum teleportation over a 14-km polarization-stabilized telecom fiber link in Saarbrücken, using an SCPD photon pair source and a single trapped 40Ca+ ion.
DOI
10.1364/quantum.2024.qtu4b.6

Related papers

Demonstration of quantum network protocols over a 14-km urban fiber link

Stephan Kucera, Christian Haen, Elena Arenskötter +9 more

Abstract We report on the implementation of quantum entanglement distribution and quantum state teleportation over a 14.4 km urban dark-fiber link, which is partially underground, partially overhead, and patched in several stations. We characterize the link for its use as a quantum channel and realize its active polarization stabilization. Using a type-II cavity-enhanced SPDC photon pair source, a 40 Ca + single-ion quantum memory, and quantum frequency conversion to the telecom C-band, we demonstrate photon-photon entanglement, ion-photon entanglement, and teleportation of a qubit state from the ion onto a remote telecom photon, all realized over the urban fiber link.

npj Quantum Information•Sep 14, 2024•39 citations

Demonstration of quantum network protocols over a 14-km urban fiber link

Stephan Kucera, Christian Haen, Elena Arenskötter +9 more

We report on the implementation of quantum entanglement distribution and quantum state teleportation over a 14.4-km urban dark-fiber link, which is partially underground, partially overhead, and patched in several stations. We characterize the link for its use as a quantum channel and realize its active polarization stabilization. Using a type-II cavity-enhanced SPDC photon pair source, a $^{40}$Ca$^{+}$ single-ion quantum memory, and quantum frequency conversion to the telecom C-band, we demonstrate photon-photon entanglement, ion-photon entanglement, and teleportation of a qubit state from the ion onto a remote telecom photon, all realized over the urban fiber link.

arXiv:2404.04958•Apr 7, 2024•0 citations

Trapped Ion Quantum Networking and Telecommunications Coexisting on One Fiber

Denton Wu, Mingzhe Han, Zehao Wang +5 more

Research into long-distance quantum memory-based networking to date has exclusively used dark fibers. This avoids the detector background from telecommunications (telecom) traffic, but as a result excludes many fibers deployed in the field. If memory-photon entanglement and telecom signals coexist on one fiber, the entire classical fiber infrastructure becomes available for quantum links. We present the first experimental demonstration of such coexistence. Ion-photon entanglement using 1092 nm photons emitted by a Strontium-88 ion is distributed over a deployed 2.8 km fiber loop which carries Ethernet and 5G traffic. All classical control signals required to coordinate the quantum transmitter and receiver systems co-propagate on the same fiber. These include fiber sensing for polarization stabilization. Our results demonstrate that memory-based quantum networks can be realized on active classical network infrastructure.

quant-pharXiv:2609.06387•Sep 8, 2026•0 citations

Quantum key distribution with atom-photon entanglement for an urban fiber link

Jonas Meiers, Christian Haen, Max Bergerhoff +2 more

We implement a protocol for quantum key distribution based on atom-photon-entanglement over a 14-km urban dark-fiber link, using single photons from a 40Ca+-ion and active polarization correction.

Quantum 2.0 Conference and Exhibition•Jan 1, 2024•0 citations

Entanglement Distribution over an Actively Polarization-Stabilized Commercial Fiber Link

Akriti Raj, Tobias Bauer, Christian Haen +6 more

We present a polarization-entangled photon pair source at telecom wavelength from an AlGaAs Bragg reflection waveguide. We demonstrate preservation of entanglement after distribution over an actively stabilized 28 km metropolitan dark fiber link.

•Jan 1, 2026•0 citations

Entanglement distribution over a polarization-stabilized aerial fiber

Yicheng Shi, Jing Su, Anouar Rahmouni +9 more

Distributing quantum entanglement over telecommunication fiber is a fundamental task in metropolitan-scale quantum networks, enabling advanced applications such as quantum-secured communication, quantum sensing, and distributed quantum computing. Although polarization entanglement is relatively easy to generate and manipulate, its distribution across deployed fibers is challenging because of the time-varying polarization transformations imposed by the fiber, which must be actively stabilized. In this work, we experimentally demonstrate the distribution of polarization-entangled photons over a 62 km, partially aerial fiber between the National Institute of Standards and Technology and the University of Maryland. With polarization stabilization applied to the fiber, we achieved a photon pair rate of approximately 1500s −1 and observed a time-averaged CHSH inequality parameter of S =2.34±0.37. During a continuous 24 h experiment, time-multiplexed polarization compensation sessions only cost 7.2% of the total link operation time, leaving an entanglement distribution uptime of 92.8%. Our results demonstrate the feasibility of distributing polarization-entangled photons over challenging fiber conditions, which is an important step toward the practical deployment of quantum networks.

Journal of Optical Communications and Networking•May 26, 2026•1 citation
Abstract We report on the implementation of quantum entanglement distribution and quantum state teleportation over a 14.4 km urban dark-fiber link, which is partially underground, partially overhead, and patched in several stations. We characterize the link for its use as a quantum channel and realize its active polarization stabilization. Using a type-II cavity-enhanced SPDC photon pair source, a 40 Ca + single-ion quantum memory, and quantum frequency conversion to the telecom C-band, we demonstrate photon-photon entanglement, ion-photon entanglement, and teleportation of a qubit state from the ion onto a remote telecom photon, all realized over the urban fiber link.
We report on the implementation of quantum entanglement distribution and quantum state teleportation over a 14.4-km urban dark-fiber link, which is partially underground, partially overhead, and patched in several stations. We characterize the link for its use as a quantum channel and realize its active polarization stabilization. Using a type-II cavity-enhanced SPDC photon pair source, a 40^{40}40Ca+^{+}+ single-ion quantum memory, and quantum frequency conversion to the telecom C-band, we demonstrate photon-photon entanglement, ion-photon entanglement, and teleportation of a qubit state from the ion onto a remote telecom photon, all realized over the urban fiber link.
Research into long-distance quantum memory-based networking to date has exclusively used dark fibers. This avoids the detector background from telecommunications (telecom) traffic, but as a result excludes many fibers deployed in the field. If memory-photon entanglement and telecom signals coexist on one fiber, the entire classical fiber infrastructure becomes available for quantum links. We present the first experimental demonstration of such coexistence. Ion-photon entanglement using 1092 nm photons emitted by a Strontium-88 ion is distributed over a deployed 2.8 km fiber loop which carries Ethernet and 5G traffic. All classical control signals required to coordinate the quantum transmitter and receiver systems co-propagate on the same fiber. These include fiber sensing for polarization stabilization. Our results demonstrate that memory-based quantum networks can be realized on active classical network infrastructure.
Distributing quantum entanglement over telecommunication fiber is a fundamental task in metropolitan-scale quantum networks, enabling advanced applications such as quantum-secured communication, quantum sensing, and distributed quantum computing. Although polarization entanglement is relatively easy to generate and manipulate, its distribution across deployed fibers is challenging because of the time-varying polarization transformations imposed by the fiber, which must be actively stabilized. In this work, we experimentally demonstrate the distribution of polarization-entangled photons over a 62 km, partially aerial fiber between the National Institute of Standards and Technology and the University of Maryland. With polarization stabilization applied to the fiber, we achieved a photon pair rate of approximately 1500s −1 and observed a time-averaged CHSH inequality parameter of S =2.34±0.37. During a continuous 24 h experiment, time-multiplexed polarization compensation sessions only cost 7.2% of the total link operation time, leaving an entanglement distribution uptime of 92.8%. Our results demonstrate the feasibility of distributing polarization-entangled photons over challenging fiber conditions, which is an important step toward the practical deployment of quantum networks.