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

Optica

Efficient distribution of high-dimensional entanglement through 11 km fiber

Xiao‐Min Hu, Wen-Bo Xing, Bi‐Heng Liu, De‐Yong He, Huan Cao, Yu Guo, Chao Zhang, Hao Zhang, Yun‐Feng Huang, Chuan‐Feng Li, Guang‐Can Guo

Published Jun 8, 2020• 74 citations
Publisher

Abstract

High-dimensional entanglement enriches our understanding of entanglement and shows many advantages in quantum communications tasks, so its long-distance distribution is a key technology. Here, we use multicore fiber to distribute four-dimensional (4D) entanglement over 11 km. The observed fidelity is F = 0.921 ± 0.001 , which is feasible for high-dimensional quantum networks. We observed the violation of high-dimensional Bell inequality ( I 4 = 2.635 ± 0.014 ) and steering inequality ( S 4 = 1.900 ± 0.003 ) for a 4D system over a distance of 11 km and finally demonstrated 4D quantum key distribution based on entanglement in proof of principle. Our work provides an experimental platform for high-dimensional quantum technologies and enables the intracity high-dimensional quantum network.

DOI
10.1364/optica.388773

Related papers

Four-dimensional entanglement distribution over 100 km

Takuya Ikuta, Hiroki Takesue

High-dimensional quantum entanglement can enrich the functionality of quantum information processing. For example, it can enhance the channel capacity for linear optic superdense coding and decrease the error rate threshold of quantum key distribution. Long-distance distribution of a high-dimensional entanglement is essential for such advanced quantum communications over a communications network. Here, we show a long-distance distribution of a four-dimensional entanglement. We employ time-bin entanglement, which is suitable for a fibre transmission, and implement scalable measurements for the high-dimensional entanglement using cascaded Mach-Zehnder interferometers. We observe that a pair of time-bin entangled photons has more than 1 bit of secure information capacity over 100 km. Our work constitutes an important step towards secure and dense quantum communications in a large Hilbert space.

arXiv:1801.06382•Scientific Reports•Jan 10, 2018•47 citations

High-dimensional quantum key distribution using energy-time entanglement over 242 km partially deployed fiber

Jingyuan Liu, Zhihao Lin, Dongning Liu +5 more

Abstract Entanglement-based quantum key distribution (QKD) is an essential ingredient in quantum communication, owing to the property of source-independent security and the potential on constructing large-scale quantum communication networks. However, implementation of entanglement-based QKD over long-distance optical fiber links is still challenging, especially over deployed fibers. In this work, we report an experimental QKD using energy-time entangled photon pairs that transmit over optical fibers of 242 km (including a section of 19 km deployed fibers). The QKD is realized through the protocol of dispersive-optics QKD (DO-QKD) with high-dimensional encoding to utilize coincidence counts more efficiently. A reliable, high-accuracy time synchronization technology for long-distance entanglement-based QKD is developed based on the distribution of optical pulses in quantum channels. Our system operates continuously for more than 7 d without active polarization or phase calibration. We ultimately generate secure keys with secure key rates of 0.22 bps and 0.06 bps in the asymptotic and finite-size regimes, respectively. It shows that entanglement-based DO-QKD is reliable for long-distance realization in the field if its high requirement on time synchronization is satisfied.

arXiv:2212.02695•Quantum Science and Technology•Sep 28, 2023•42 citations

Toward Long-Haul Distribution of Multidimensional Spatially-Entangled Photons over Multicore Fibers

Amin Azaridoodaran, Mohammad Awwad, Cheng Guo +1 more

Spatial division multiplexing is a key technology for increasing the capacity of the classical optical fiber networks. It also provides additional degrees of freedom for photon entanglement and transmission in quantum communication networks. This paper describes steps toward generating a four-dimensional, spatially-entangled state and its distribution over multi-km-long four-core fibers. We generate four mutually coherent beams using a spatial light modulator and investigate their simultaneous coupling into a four-core fiber. We also verify the stability of both the relative phase and polarization between the cores over a 10 km of a four-core fiber.

IEEE MetroCon•Nov 12, 2025•1 citation

Long-Distance Quantum Teleportation and High-Dimensional Entanglement Distribution Over Optical Fiber

Hiroki Takesue, Takuya Ikuta

We present two technologies for advanced quantum communication systems. The first is quantum teleportation over 100 km of fiber using highly-efficient superconducting single photon detectors. The second is generation and long-distance distribution of high-dimensional time-bin entanglement, which was enabled by using cascaded delay interferometers.

IEEE/LEOS Summer Topical Meetings•Jul 1, 2018•0 citations

Hyperentanglement quantum communication over a 50 km noisy fiber channel

Zhen-Qiu Zhong, Xiao-Hai Zhan, Jia-Lin Chen +7 more

High-dimensional entanglement not only offers a high security level for quantum communication but also promises improved information capacity and noise resistance of the system. However, due to various constraints on different high-dimensional degrees of freedom, whether these advantages can bring improvement to the actual implementation is still not well proven. Here we present a scheme to fully utilize these advantages over long-distance noisy fiber channels. We exploit polarization and time-bin hyperentanglement to achieve high-dimensional coding, and observe significant enhancements in secure key rates and noise tolerance that surpass the capabilities of qubit systems. Moreover, the demonstration achieves a distribution up to 50 km, which is the longest distance for high-dimensional entanglement-based quantum key distribution up to date, to our knowledge. Our demonstration validates the potential of high-dimensional entanglement for quantum communications over long-distance noisy channels, paving the way for a resilient and resource-efficient quantum network.

Optica•Jun 25, 2024•43 citations

Practical high-dimensional quantum key distribution protocol over deployed multicore fiber

Mujtaba Zahidy, Domenico Ribezzo, Claudia De Lazzari +12 more

Quantum key distribution (QKD) is a secure communication scheme for sharing symmetric cryptographic keys based on the laws of quantum physics, and is considered a key player in the realm of cyber-security. A critical challenge for QKD systems comes from the fact that the ever-increasing rates at which digital data are transmitted require more and more performing sources of quantum keys, primarily in terms of secret key generation rate. High-dimensional QKD based on path encoding has been proposed as a candidate approach to address this challenge. However, while proof-of-principle demonstrations based on lab experiments have been reported in the literature, demonstrations in realistic environments are still missing. Here we report the generation of secret keys in a 4-dimensional hybrid time-path-encoded QKD system over a 52-km deployed multicore fiber link forming by looping back two cores of a 26-km 4-core optical fiber. Our results indicate that robust high-dimensional QKD can be implemented in a realistic environment by combining standard telecom equipment with emerging multicore fiber technology.

Nature Communications•Feb 23, 2024•93 citations
High-dimensional entanglement enriches our understanding of entanglement and shows many advantages in quantum communications tasks, so its long-distance distribution is a key technology. Here, we use multicore fiber to distribute four-dimensional (4D) entanglement over 11 km. The observed fidelity is F = 0.921 ± 0.001 , which is feasible for high-dimensional quantum networks. We observed the violation of high-dimensional Bell inequality ( I 4 = 2.635 ± 0.014 ) and steering inequality ( S 4 = 1.900 ± 0.003 ) for a 4D system over a distance of 11 km and finally demonstrated 4D quantum key distribution based on entanglement in proof of principle. Our work provides an experimental platform for high-dimensional quantum technologies and enables the intracity high-dimensional quantum network.
High-dimensional quantum entanglement can enrich the functionality of quantum information processing. For example, it can enhance the channel capacity for linear optic superdense coding and decrease the error rate threshold of quantum key distribution. Long-distance distribution of a high-dimensional entanglement is essential for such advanced quantum communications over a communications network. Here, we show a long-distance distribution of a four-dimensional entanglement. We employ time-bin entanglement, which is suitable for a fibre transmission, and implement scalable measurements for the high-dimensional entanglement using cascaded Mach-Zehnder interferometers. We observe that a pair of time-bin entangled photons has more than 1 bit of secure information capacity over 100 km. Our work constitutes an important step towards secure and dense quantum communications in a large Hilbert space.
Abstract Entanglement-based quantum key distribution (QKD) is an essential ingredient in quantum communication, owing to the property of source-independent security and the potential on constructing large-scale quantum communication networks. However, implementation of entanglement-based QKD over long-distance optical fiber links is still challenging, especially over deployed fibers. In this work, we report an experimental QKD using energy-time entangled photon pairs that transmit over optical fibers of 242 km (including a section of 19 km deployed fibers). The QKD is realized through the protocol of dispersive-optics QKD (DO-QKD) with high-dimensional encoding to utilize coincidence counts more efficiently. A reliable, high-accuracy time synchronization technology for long-distance entanglement-based QKD is developed based on the distribution of optical pulses in quantum channels. Our system operates continuously for more than 7 d without active polarization or phase calibration. We ultimately generate secure keys with secure key rates of 0.22 bps and 0.06 bps in the asymptotic and finite-size regimes, respectively. It shows that entanglement-based DO-QKD is reliable for long-distance realization in the field if its high requirement on time synchronization is satisfied.
Spatial division multiplexing is a key technology for increasing the capacity of the classical optical fiber networks. It also provides additional degrees of freedom for photon entanglement and transmission in quantum communication networks. This paper describes steps toward generating a four-dimensional, spatially-entangled state and its distribution over multi-km-long four-core fibers. We generate four mutually coherent beams using a spatial light modulator and investigate their simultaneous coupling into a four-core fiber. We also verify the stability of both the relative phase and polarization between the cores over a 10 km of a four-core fiber.
High-dimensional entanglement not only offers a high security level for quantum communication but also promises improved information capacity and noise resistance of the system. However, due to various constraints on different high-dimensional degrees of freedom, whether these advantages can bring improvement to the actual implementation is still not well proven. Here we present a scheme to fully utilize these advantages over long-distance noisy fiber channels. We exploit polarization and time-bin hyperentanglement to achieve high-dimensional coding, and observe significant enhancements in secure key rates and noise tolerance that surpass the capabilities of qubit systems. Moreover, the demonstration achieves a distribution up to 50 km, which is the longest distance for high-dimensional entanglement-based quantum key distribution up to date, to our knowledge. Our demonstration validates the potential of high-dimensional entanglement for quantum communications over long-distance noisy channels, paving the way for a resilient and resource-efficient quantum network.
Quantum key distribution (QKD) is a secure communication scheme for sharing symmetric cryptographic keys based on the laws of quantum physics, and is considered a key player in the realm of cyber-security. A critical challenge for QKD systems comes from the fact that the ever-increasing rates at which digital data are transmitted require more and more performing sources of quantum keys, primarily in terms of secret key generation rate. High-dimensional QKD based on path encoding has been proposed as a candidate approach to address this challenge. However, while proof-of-principle demonstrations based on lab experiments have been reported in the literature, demonstrations in realistic environments are still missing. Here we report the generation of secret keys in a 4-dimensional hybrid time-path-encoded QKD system over a 52-km deployed multicore fiber link forming by looping back two cores of a 26-km 4-core optical fiber. Our results indicate that robust high-dimensional QKD can be implemented in a realistic environment by combining standard telecom equipment with emerging multicore fiber technology.