https://doi.org/10.1140/epjqt/s40507-024-00267-5
Research
Fully controllable time-bin entangled states distributed over 100-km single-mode fibers
1
Quantum Sensing Research Section, Electronics and Telecommunications Research Institute, 34129, Daejeon, Republic of Korea
2
Photonics Planar Integration (PPI), 61008, Gwangju, Republic of Korea
Received:
8
May
2024
Accepted:
26
August
2024
Published online:
4
September
2024
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 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
, 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
with a violation of the CHSH Bell’s inequality by 6 standard deviations. The prepared states had an average fidelity of
at the source and an average fidelity of
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.
Key words: Quantum communication / Quantum networks / Entanglement distribution / Time-bin qubits
© The Author(s) 2024
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