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A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
Spin entanglement, decoherence and Bohm's EPR paradox
E G Cavalcanti1, P D Drummond, H A Bachor
1Centre for Quantum Dynamics, Griffith University, Brisbane, QLD 4111, Australia.
Optics Express
|April 8, 2010
Summary
This study provides criteria for quantum entanglement and the Einstein-Podolsky-Rosen (EPR) paradox in spin-entangled particles, analyzing decoherence effects. Results show entanglement is robust, but the EPR paradox requires higher transmission efficiency.
Area of Science:
- Quantum Physics
- Quantum Information Science
- Atomic and Molecular Physics
Background:
- Entanglement and the Einstein-Podolsky-Rosen (EPR) paradox are fundamental concepts in quantum mechanics.
- Decoherence, caused by environmental interactions like absorption and state purity errors, poses a significant challenge to maintaining quantum states.
Purpose of the Study:
- To establish criteria for achieving entanglement and the EPR paradox in spin-entangled systems.
- To analyze the impact of decoherence on these quantum phenomena for both two-qubit and macroscopic systems.
Main Methods:
- Derivation of theoretical criteria for entanglement and EPR paradox.
- Analysis of decoherence effects due to absorption and state purity errors.
- Calculations for specific scenarios: two-qubit photonic states and macroscopic systems of ultra-cold atoms or photons.
Main Results:
- Entanglement is achievable for all transmission efficiencies in two-qubit photonic states, provided state purity exceeds a threshold.
- Demonstration of Bohm's spin EPR paradox requires a critical transmission efficiency (calculated at 58% for photons).
- Macroscopic systems exhibit surprising insensitivity to loss decoherence, with entanglement and EPR paradox criteria met at efficiencies greater than 1/3 and 2/3, respectively.
Conclusions:
- The study provides practical criteria for observing entanglement and the EPR paradox under realistic decoherence conditions.
- Quantum phenomena like entanglement and the EPR paradox can be robustly demonstrated even in macroscopic quantum systems.
- The findings suggest feasibility with current quantum optical technologies and highlight the potential for macroscopic quantum experiments.
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