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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
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Long-Distance Distribution of Atom-Photon Entanglement at Telecom Wavelength
Tim van Leent1,2, Matthias Bock3, Robert Garthoff1,2
1Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 München, Germany.
Physical Review Letters
|January 25, 2020
Summary
Researchers created entanglement between a Rubidium-87 atom and a telecom photon, transmitting it through 20 km of fiber. This breakthrough advances quantum networks by enabling efficient quantum state distribution.
Area of Science:
- Quantum Information Science
- Quantum Communication Networks
- Atomic Physics
Background:
- Entanglement between stationary quantum memories and photonic channels is crucial for quantum networks.
- Entanglement distillation is key for efficient quantum state distribution.
Purpose of the Study:
- To generate and observe entanglement between a Rubidium-87 atom and a telecom photon.
- To demonstrate the feasibility of distributing entangled quantum states over long distances via optical fiber.
Main Methods:
- Utilized polarization-preserving quantum frequency conversion to shift photon wavelength from 780 nm to 1522 nm (telecom S band).
- Entangled a Rubidium-87 atom's spin state with a photon and transmitted it through optical fiber.
Main Results:
- Achieved an external device conversion efficiency of 57%.
- Observed an entanglement fidelity of ≥78.5±0.9% between the atom and telecom photon after 20 km fiber transmission.
- Identified atomic state decoherence as the primary limitation.
Conclusions:
- Demonstrated a significant milestone towards large-scale quantum information distribution.
- The developed method shows promise for building robust quantum networks.
- Further improvements in atomic coherence are needed for even higher fidelities.
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