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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
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Postselected Entanglement between Two Atomic Ensembles Separated by 12.5 km.
Xi-Yu Luo1,2,3, Yong Yu1,2,3, Jian-Long Liu1,2,3
1Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China.
Physical Review Letters
|August 12, 2022
Summary
Researchers established entanglement between two atomic quantum memories separated by 12.5 km. This breakthrough advances the development of practical, metropolitan-scale quantum networks by demonstrating reliable quantum memory entanglement over long distances.
Area of Science:
- Quantum Information Science
- Quantum Networking
- Atomic Physics
Background:
- Quantum internet promises to connect quantum resources for advanced applications.
- A key prototype involves entangled, spatially separated quantum memories.
- Establishing entanglement over distance is crucial for quantum network realization.
Purpose of the Study:
- To demonstrate entanglement between two physically separated atomic quantum memories.
- To investigate the feasibility of a metropolitan-scale quantum network.
Main Methods:
- Created atom-photon entanglement in one node.
- Transmitted photons over a 20.5 km deployed fiber using frequency conversion.
- Stored photons in a second atomic quantum memory via electromagnetically induced transparency.
- Verified memory-memory entanglement through photon retrieval.
Main Results:
- Achieved postselected entanglement between atomic quantum memories separated by 12.5 km.
- Demonstrated high-fidelity entanglement (90%) verified via photon retrieval.
- Utilized low-loss fiber transmission with frequency up- and down-conversion.
Conclusions:
- This experiment represents a significant advancement towards practical quantum networks.
- The successful entanglement over 12.5 km paves the way for metropolitan-scale quantum communication.
- The methods employed are crucial for overcoming distance limitations in quantum networking.
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