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

Symmetric Polarization-Maintaining Fibers for Preserving Polarization and Time-Energy Entanglement for Satellite Quantum Links

Uday Chandrashekara, Karen Lozano-Mendez, Meritxell Cabrejo Ponce, Melo Luna, Fabian Steinlechner

Published Jan 1, 2026• 0 citations
OpenAlex

Abstract

We implemented robust distribution of polarization and time-energy entanglement using polarization-maintaining fibers. By mitigating polarization scrambling, this approach reduces receiver complexity from three-dimensional polarization control to single-dimensional phase stabilization for satellite-based quantum communication.

Related papers

Passive Polarization Stabilization for Robust Entanglement Distribution via Cross-Aligned Polarization Maintaining Fiber Pairs

Jin-Woo Kim, Minchul Kim, Jiho Park +4 more

Maintaining stable entanglement distribution through perturbed fiber links is essential for practical quantum-optics experiments, yet it remains challenging because of polarization fluctuations and phase or temporal-delay variations. We demonstrate stable entangled-photon transmission using a cross-aligned polarization-maintaining fiber (CAPMF) structure composed of two polarization-maintaining fiber sections with mutually orthogonal principal axes. The CAPMF configuration passively compensates polarization fluctuations without real-time active polarization control. We theoretically analyze the CAPMF structure and experimentally verify its stabilization performance under external mechanical perturbations. In the experiment, the single-mode fiber configuration yields an average visibility of $0.7655$ and a CHSH value of $S=1.7714$, whereas the CAPMF configuration maintains an average visibility of $0.9843$ and a CHSH value of $S=2.6838$. These results show that CAPMF offers a simple and robust architecture for stabilizing fiber-interface sections in practical entanglement-distribution systems.

quant-pharXiv:2512.01229•EPJ Quantum Technology•Dec 2, 2025•0 citations

An intrinsic-stabilization polarization encoder for quantum key distribution

Huaxing Xu, Shaohua Wang

An intrinsic-stabilization polarization encoder based on a PBS-Sagnac loop with a polarization-maintain-fiber arm for quantum key distribution is proposed, which is completely immune to polarization disturbance and can be applied for quantum satellite communications.

Sixth Symposium on Novel Optoelectronic Detection Technology and Applications•Apr 17, 2020•4 citations

Polarization Entangled Photon Sources for Free-Space Quantum Key Distribution

Ramy Tannous

Free-space quantum key distribution has recently achieved several milestones, such as \nthe launch and results of the first quantum satellite, Micius. The emergence of quantum satellites has certainly made progress towards the realization of a global quantum cryptographic network. In this thesis, two challenges in the development of an optical quantum ground station \nfor a free-space quantum satellite link are studied. The first is the development of a high brightness, fiber pigtailed waveguide that is to be used as a polarization entangled photon source. The high pair production rate is required in order to meet the requirements for a satellite up-link configuration. The portability, robustness and ease of alignment were motivations for choosing a fiber pigtailed source. Certain challenges that are fundamental to the source design were characterized and several solutions to these challenges were investigated. The other main investigation in this thesis, is the development of a passive polarization \ncompensation using polarization maintaining fibers. The birefringence in standard single mode optical fibers causes random polarization rotations to the light passing through the fiber. Polarization maintaining fibers, though very high in birefringence, are used with entangled photons and techniques from reference frame independent quantum key distribution protocols are shown to compensate for random polarization rotations while preserving the entanglement. In addition, the feasibility of the protocol using the polarization maintaining fibers is investigated. \nThrough various studies, experiments, and component design, the feasibility of a pigtailed waveguide entangled photon source has been shown to need further investigation, while the feasibility of implementing polarization maintaining fibers to the ground station has been shown to be effective. It is particularly effective as a passive polarization compensation system that uses entanglement, however a similar concept is effective for non-entangled single photons. This work contributes to a long line of achievements leading towards satellite implementations of quantum key distribution for an eventual global quantum cryptographic network.

•Aug 27, 2018•1 citation

Phase Control in Polarization Maintaining Fiber for Quantum Key Distribution

Wilson Wu, Ramy Tannous, Kimia Mohammadi +3 more

Polarization encodings for quantum key distribution (QKD) in fiber suffer from strain- and temperature-induced polarization instabilities, which can be addressed using a polarization control system. The polarization instability can be reduced to a single phase parameter by using polarization maintaining (PM) fiber. However, phase control in PM fiber is typically applied to phase stabilization on signals coupled into only one bases of the PM fiber, making such methods insufficient for QKD which encodes signals in orthogonal bases. We describe an active system to monitor and control the phase in PM fiber to enable PM fiber based QKD systems.

Photonics North (PN)•Jun 12, 2023•0 citations

Efficient polarization-entangled state compensation in quantum entanglement distribution

Xiaoyan Zhou, Hao Qin, Bo Li +4 more

The polarization states of the photons will be changed when distributing polarization-entangled photon pairs through their independent optical channels, whether satellite-based free-space or fiber-based links. Thus, it is essential to reconstruct the initial polarization-entangled state between their receiving ends. Here, we present an efficient compensation method based on coincidence measurements of entangled photons to restore the entanglement state. A unitary polarization transformation performed on a single optical link is sufficient using our method. Furthermore, we experiment to demonstrate the feasibility of this method by implementing the transformation with a set of three waveplates and employing one-step feedback. This study provides an efficient compensation technology for preserving the polarization-entangled state, which can be directly applied to applications involving quantum entanglement distribution.

Optics Express•May 15, 2025•1 citation

Towards high-dimensional quantum communication in space (Conference Presentation)

Fabian Steinlechner

Photonic entanglement is a fundamental resource in quantum information processing and its distribution between distant parties is a key challenge in quantum communications. Optical satellite links allow transmitting entangled photons over longer distances than currently possible on ground and could provide a path towards global quantum communication networks. The majority of current photonic free-space quantum communication systems, including two recent quantum satellite experiments, use two-dimensional polarization encoding, where each photon can carry at most a single bit of quantum information. Encoding additional qubits in the high-dimensional spatio-temporal degrees of freedom could not only increase channel capacities but also improve robustness with respect to noise and eavesdropping in quantum cryptography. Here, we give an overview of our efforts towards exploiting high-dimensional entanglement in long-distance free-space quantum communications. We report on the results of a first feasibility study, in which we used polarization / energy-time hyperentanglement to increase the dimensionality of the state space and transmit genuine 4-dimensional entanglement via an intra-city free-space link. We discuss how we intend to extend this approach to applications in noise-tolerant large-alphabet quantum key distribution via free-space links, and, ultimately, experiments with satellites.

Quantum Computing, Communication, and Simulation•Mar 14, 2018•0 citations
Maintaining stable entanglement distribution through perturbed fiber links is essential for practical quantum-optics experiments, yet it remains challenging because of polarization fluctuations and phase or temporal-delay variations. We demonstrate stable entangled-photon transmission using a cross-aligned polarization-maintaining fiber (CAPMF) structure composed of two polarization-maintaining fiber sections with mutually orthogonal principal axes. The CAPMF configuration passively compensates polarization fluctuations without real-time active polarization control. We theoretically analyze the CAPMF structure and experimentally verify its stabilization performance under external mechanical perturbations. In the experiment, the single-mode fiber configuration yields an average visibility of 0.76550.76550.7655 and a CHSH value of S=1.7714S=1.7714S=1.7714, whereas the CAPMF configuration maintains an average visibility of 0.98430.98430.9843 and a CHSH value of S=2.6838S=2.6838S=2.6838. These results show that CAPMF offers a simple and robust architecture for stabilizing fiber-interface sections in practical entanglement-distribution systems.
Free-space quantum key distribution has recently achieved several milestones, such as \nthe launch and results of the first quantum satellite, Micius. The emergence of quantum satellites has certainly made progress towards the realization of a global quantum cryptographic network. In this thesis, two challenges in the development of an optical quantum ground station \nfor a free-space quantum satellite link are studied. The first is the development of a high brightness, fiber pigtailed waveguide that is to be used as a polarization entangled photon source. The high pair production rate is required in order to meet the requirements for a satellite up-link configuration. The portability, robustness and ease of alignment were motivations for choosing a fiber pigtailed source. Certain challenges that are fundamental to the source design were characterized and several solutions to these challenges were investigated. The other main investigation in this thesis, is the development of a passive polarization \ncompensation using polarization maintaining fibers. The birefringence in standard single mode optical fibers causes random polarization rotations to the light passing through the fiber. Polarization maintaining fibers, though very high in birefringence, are used with entangled photons and techniques from reference frame independent quantum key distribution protocols are shown to compensate for random polarization rotations while preserving the entanglement. In addition, the feasibility of the protocol using the polarization maintaining fibers is investigated. \nThrough various studies, experiments, and component design, the feasibility of a pigtailed waveguide entangled photon source has been shown to need further investigation, while the feasibility of implementing polarization maintaining fibers to the ground station has been shown to be effective. It is particularly effective as a passive polarization compensation system that uses entanglement, however a similar concept is effective for non-entangled single photons. This work contributes to a long line of achievements leading towards satellite implementations of quantum key distribution for an eventual global quantum cryptographic network.
Polarization encodings for quantum key distribution (QKD) in fiber suffer from strain- and temperature-induced polarization instabilities, which can be addressed using a polarization control system. The polarization instability can be reduced to a single phase parameter by using polarization maintaining (PM) fiber. However, phase control in PM fiber is typically applied to phase stabilization on signals coupled into only one bases of the PM fiber, making such methods insufficient for QKD which encodes signals in orthogonal bases. We describe an active system to monitor and control the phase in PM fiber to enable PM fiber based QKD systems.
The polarization states of the photons will be changed when distributing polarization-entangled photon pairs through their independent optical channels, whether satellite-based free-space or fiber-based links. Thus, it is essential to reconstruct the initial polarization-entangled state between their receiving ends. Here, we present an efficient compensation method based on coincidence measurements of entangled photons to restore the entanglement state. A unitary polarization transformation performed on a single optical link is sufficient using our method. Furthermore, we experiment to demonstrate the feasibility of this method by implementing the transformation with a set of three waveplates and employing one-step feedback. This study provides an efficient compensation technology for preserving the polarization-entangled state, which can be directly applied to applications involving quantum entanglement distribution.
Photonic entanglement is a fundamental resource in quantum information processing and its distribution between distant parties is a key challenge in quantum communications. Optical satellite links allow transmitting entangled photons over longer distances than currently possible on ground and could provide a path towards global quantum communication networks. The majority of current photonic free-space quantum communication systems, including two recent quantum satellite experiments, use two-dimensional polarization encoding, where each photon can carry at most a single bit of quantum information. Encoding additional qubits in the high-dimensional spatio-temporal degrees of freedom could not only increase channel capacities but also improve robustness with respect to noise and eavesdropping in quantum cryptography. Here, we give an overview of our efforts towards exploiting high-dimensional entanglement in long-distance free-space quantum communications. We report on the results of a first feasibility study, in which we used polarization / energy-time hyperentanglement to increase the dimensionality of the state space and transmit genuine 4-dimensional entanglement via an intra-city free-space link. We discuss how we intend to extend this approach to applications in noise-tolerant large-alphabet quantum key distribution via free-space links, and, ultimately, experiments with satellites.