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Updated: Jun 22, 2026
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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Phase-compensated ultra-bright source of entangled photons
Optics Express
|June 6, 2009
Summary
Researchers developed the brightest entangled photon source by using compensation crystals to overcome decoherence. This breakthrough achieved over two million entangled pairs per second and the largest violation of Bell's inequality to date.
Area of Science:
- Quantum optics
- Entanglement sources
- Photonics
Background:
- Increasing the brightness of type-I entanglement sources typically involves expanding the collected solid angle of down-conversion.
- This expansion, however, introduces effective decoherence due to angle-dependent phase shifts, limiting source performance.
- Overcoming this decoherence is crucial for advancing quantum technologies.
Purpose of the Study:
- To develop a brighter source of entangled photons.
- To mitigate decoherence issues associated with increased solid angle collection.
- To achieve a record violation of Bell's inequality.
Main Methods:
- Utilized specially designed compensation crystals to counteract angle-dependent phase shifts.
- Implemented techniques to increase the collected solid angle of spontaneous parametric down-conversion.
- Measured the rate of entangled photon pair generation and the violation of Bell's inequality.
Main Results:
- Created the brightest source of entangled photons reported to date.
- Achieved a generation rate exceeding two million measured entangled pairs per second.
- Recorded the largest reported violation of Bell's inequality (1239 sigma).
Conclusions:
- Compensation crystals effectively reverse decoherence, enabling brighter entanglement sources.
- The developed source represents a significant advancement in quantum photonics.
- This high-brightness, high-fidelity source has implications for quantum communication and computation.
