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

arXiv:quant-ph/0404124 · Physical Review Letters

Distribution of Time-Bin Entangled Qubits over 50 km of Optical Fiber

I. Marcikic, Hugues de Riedmatten, Wolfgang Tittel, Hugo Zbinden, Matthieu Legré, Nicolas Gisin

Published Oct 28, 2004• 343 citations
arXivHTMLPDF

Abstract

We report experimental distribution of time-bin entangled qubits over 50 km of optical fibers. Using actively stabilized preparation and measurement devices we demonstrate violation of the Clauser-Horne-Shimony-Holt Bell inequality by more than 15 standard deviations without removing the detector noise. In addition we report a proof-of principle experiment of quantum key distribution over 50 km of optical fibers using entangled photon.

DOI
10.1103/physrevlett.93.180502

Related papers

Entanglement distribution over 300 km of fiber

Takahiro Inagaki, Nobuyuki Matsuda, Osamu Tadanaga +2 more

We report the distribution of time-bin entangled photon pairs over 300 km of optical fiber. We realized this by using a high-speed and high signal-to-noise ratio entanglement generation/evaluation setup that consists of periodically poled lithium niobate waveguides and superconducting single photon detectors. The observed two-photon interference fringes exhibited a visibility of 84%. We confirmed the violation of Bell's inequality by 2.9 standard deviations.

arXiv:1310.5473•Optics Express•Sep 24, 2013•198 citations

Distribution of Entangled Photon Pairs over 300 km of Optical Fiber

Takahiro Inagaki, Hiroki Takesue

We describe our recent experiment on the distribution of time-bin entangled photon pairs over 300 km of optical fiber, which set a record for long-distance distribution of quantum information.This experiment was achieved by using a high-speed and high signal-to-noise ratio entanglement generation/evaluation setup consisting of periodically poled lithium niobate waveguides and superconducting singlephoton detectors.We observed the violation of Bell's inequality and thus confirmed that the entangled photon pairs preserved the quantum correlation after they were separated by 300 km of fiber.

NTT technical review•Sep 1, 2014•2 citations

Long-distance distribution of time-bin entangled photon pairs over 100 km using frequency up-conversion detectors

Toshimori Honjo, Hiroki Takesue, Hidehiko Kamada +4 more

We report an experimental demonstration of the distribution of time-bin entangled photon pairs over 100 km of optical fiber. In our experiment, 1.5-mum non-degenerated time-bin entangled photon pairs were generated with a periodically poled lithium niobate (PPLN) waveguide by using the parametric down conversion process. Combining this approach with ultra-low-loss filters to eliminate the pump light and separate signal and idler photons, we obtained an efficient entangled photon pair source. To detect the photons, we used single-photon detectors based on frequency up-conversion. These detectors operated in a non-gated mode so that we could use a pulse stream of time correlated entangled photon pairs at a high repetition frequency (1 GHz). Using these elements, we distributed time-bin entangled photon pairs over 100 km of dispersion shifted fiber and performed a two-photon interference experiment. We obtained a coincidence fringe of 81.6% visibility without subtracting any background noise, such as accidental coincidence or dark count, which was good enough to violate Bell's inequality. Thus, we successfully distributed time-bin entangled photon pairs over 100 km.

Optics Express•Jan 1, 2007•74 citations

Modified E91 protocol demonstration with hybrid entanglement photon source

Mikio Fujiwara, K. Yoshino, Yoshihiro Nambu +7 more

We report on an experimental demonstration of the modified Ekert 91 protocol of quantum key distribution using a hybrid entanglement source with two different degrees of freedoms, a 1550 nm time-bin qubit and 810 nm polarization qubit. The violation of the Clauser-Horne-Shimony-Holt inequality could be demonstrated for the entanglement between the polarization qubit in free space and the time-bin qubit through 20 km fiber transmission. The secure key rate in our system is estimated 70-150 bps.

arXiv:1501.05686•Optics Express•May 29, 2014•9 citations

Fully controllable time-bin entangled states distributed over 100-km single-mode fibers

Jinwoo Kim, Jiho Park, Guhwan Kim +7 more

Quantum networks that can perform user-defined protocols beyond quantum key distribution will require fully controllable entangled quantum states. To expand the available space of generated time-bin entangled states, we demonstrate a time-bin entangled photon source that produces qubit states $|{\psi}\rangle = \alpha |{00}\rangle + \beta |{11}\rangle $ with fully controllable phase and amplitudes. Eight different two-photon states have been selected and prepared from arbitrary states on the reduced two-qubit Bloch sphere. The photon pairs encoded in the time-bin scheme were generated at 2.4 MHz with a visibility of $V = 0.9475 \pm 0.0016$ , with a violation of the CHSH Bell’s inequality by 197 standard deviations. After entanglement distribution over 100 km of single-mode fibers, we obtained a visibility of $V = 0.9541 \pm 0.0113$ with a violation of the CHSH Bell’s inequality by 6 standard deviations. The prepared states had an average fidelity of $0.9540 \pm 0.0016$ at the source and an average fidelity of $0.9353 ^{+0.0100}_{-0.0209}$ after entanglement distribution, which shows that the quantum states generated by our time-bin entangled photon source can be fully controlled potentially to a level applicable to long-distance advanced quantum network systems.

EPJ Quantum Technology•Sep 4, 2024•9 citations

Testing nonlocality over 12.4 km of underground fiber with universal time-bin qubit analyzers

Félix Bussières, Joshua A. Slater, Jeongwan Jin +2 more

We experimentally demonstrate that the nonlocal nature of time-bin entangled photonic qubits persists when one or two qubits of the pair are converted to polarization qubits. This is possible by implementing a universal time-bin qubit analyzer (UTBA), which allows the analysis of time-bin qubits in any basis. We reveal the nonlocal nature of the emitted light by violating the Clauser-Horne-Shimony-Holt inequality with measurement bases exploring all the dimensions of the Bloch sphere. Moreover, we conduct experiments where one qubit is transmitted over a 12.4 km underground fiber link and demonstrate the suitability of our scheme for use in a real-world setting. The resulting entanglement can also be interpreted as hybrid entanglement between different types of degrees of freedom of two physical systems, which could prove useful in large-scale, heterogeneous quantum networks. This work opens possibilities for testing nonlocality and for implementing new quantum communication protocols with time-bin entanglement.

arXiv:1003.0432•Physical Review A•May 10, 2010•23 citations
We report experimental distribution of time-bin entangled qubits over 50 km of optical fibers. Using actively stabilized preparation and measurement devices we demonstrate violation of the Clauser-Horne-Shimony-Holt Bell inequality by more than 15 standard deviations without removing the detector noise. In addition we report a proof-of principle experiment of quantum key distribution over 50 km of optical fibers using entangled photon.
We describe our recent experiment on the distribution of time-bin entangled photon pairs over 300 km of optical fiber, which set a record for long-distance distribution of quantum information.This experiment was achieved by using a high-speed and high signal-to-noise ratio entanglement generation/evaluation setup consisting of periodically poled lithium niobate waveguides and superconducting singlephoton detectors.We observed the violation of Bell's inequality and thus confirmed that the entangled photon pairs preserved the quantum correlation after they were separated by 300 km of fiber.
We report an experimental demonstration of the distribution of time-bin entangled photon pairs over 100 km of optical fiber. In our experiment, 1.5-mum non-degenerated time-bin entangled photon pairs were generated with a periodically poled lithium niobate (PPLN) waveguide by using the parametric down conversion process. Combining this approach with ultra-low-loss filters to eliminate the pump light and separate signal and idler photons, we obtained an efficient entangled photon pair source. To detect the photons, we used single-photon detectors based on frequency up-conversion. These detectors operated in a non-gated mode so that we could use a pulse stream of time correlated entangled photon pairs at a high repetition frequency (1 GHz). Using these elements, we distributed time-bin entangled photon pairs over 100 km of dispersion shifted fiber and performed a two-photon interference experiment. We obtained a coincidence fringe of 81.6% visibility without subtracting any background noise, such as accidental coincidence or dark count, which was good enough to violate Bell's inequality. Thus, we successfully distributed time-bin entangled photon pairs over 100 km.
Quantum networks that can perform user-defined protocols beyond quantum key distribution will require fully controllable entangled quantum states. To expand the available space of generated time-bin entangled states, we demonstrate a time-bin entangled photon source that produces qubit states $|{\psi}\rangle = \alpha |{00}\rangle + \beta |{11}\rangle $ with fully controllable phase and amplitudes. Eight different two-photon states have been selected and prepared from arbitrary states on the reduced two-qubit Bloch sphere. The photon pairs encoded in the time-bin scheme were generated at 2.4 MHz with a visibility of V=0.9475±0.0016V = 0.9475 \pm 0.0016V=0.9475±0.0016 , with a violation of the CHSH Bell’s inequality by 197 standard deviations. After entanglement distribution over 100 km of single-mode fibers, we obtained a visibility of V=0.9541±0.0113V = 0.9541 \pm 0.0113V=0.9541±0.0113 with a violation of the CHSH Bell’s inequality by 6 standard deviations. The prepared states had an average fidelity of 0.9540±0.00160.9540 \pm 0.00160.9540±0.0016 at the source and an average fidelity of 0.9353−0.0209+0.01000.9353 ^{+0.0100}_{-0.0209}0.9353−0.0209+0.0100​ after entanglement distribution, which shows that the quantum states generated by our time-bin entangled photon source can be fully controlled potentially to a level applicable to long-distance advanced quantum network systems.
We experimentally demonstrate that the nonlocal nature of time-bin entangled photonic qubits persists when one or two qubits of the pair are converted to polarization qubits. This is possible by implementing a universal time-bin qubit analyzer (UTBA), which allows the analysis of time-bin qubits in any basis. We reveal the nonlocal nature of the emitted light by violating the Clauser-Horne-Shimony-Holt inequality with measurement bases exploring all the dimensions of the Bloch sphere. Moreover, we conduct experiments where one qubit is transmitted over a 12.4 km underground fiber link and demonstrate the suitability of our scheme for use in a real-world setting. The resulting entanglement can also be interpreted as hybrid entanglement between different types of degrees of freedom of two physical systems, which could prove useful in large-scale, heterogeneous quantum networks. This work opens possibilities for testing nonlocality and for implementing new quantum communication protocols with time-bin entanglement.