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Detection of sub-shot-noise spatial correlation in high-gain parametric down conversion
O Jedrkiewicz1, Y-K Jiang, E Brambilla
1INFM, Dipartimento di Fisica e Matematica, Universita' dell'Insubria, Via Valleggio 11, 22100 Como, Italy.
Physical Review Letters
|February 9, 2005
Summary
Researchers detected sub-shot-noise spatial quantum correlations using high-gain parametric down conversion. This quantum phenomenon transitions to the classical regime due to beam narrowing at very high gain.
Area of Science:
- Quantum optics
- Nonlinear optics
Background:
- Parametric down conversion (PDC) is a key process in quantum optics for generating entangled photon pairs.
- High-gain PDC can lead to complex quantum correlations, but its behavior in the transition to the classical regime requires further investigation.
Purpose of the Study:
- To investigate spatial quantum correlations in high-gain parametric down conversion.
- To observe and analyze the transition from quantum to classical behavior in this regime.
Main Methods:
- Utilizing a 1 GW, 1 picosecond (ps) pump laser pulse for high-gain PDC.
- Employing a high-efficiency charge-coupled device (CCD) for single-shot detection.
- Performing statistical analysis on independent spatial replicas of the system.
Main Results:
- Detection of sub-shot-noise spatial quantum correlation with up to 100 photoelectrons per mode.
- Observation of clear quantum correlations between symmetrical signal and idler spatial areas in the far field.
- Experimental confirmation of the transition from the quantum to the classical regime.
Conclusions:
- The observed transition to the classical regime is attributed to the narrowing of down-converted beams at very high gain.
- High-gain PDC offers a platform for studying quantum correlations and their classical limits.
- The findings align with theoretical predictions and provide insights into nonlinear optical processes.