| Tartalmi leírás: |
We present an experimental study of polarization-entangled photon pairs, investigating the dependence of the measurement outcomes on different polarization rotation angles and the slow temporal fluctuations of the generated quantum state. Entangled photon pairs are produced and analyzed using single-photon detectors while systematically varying polarization settings on both sides. Bell tests yield an S parameter of approximately 2.52, confirming strong entanglement. The measured coincidence counts between identical measurement outcomes exhibit the expected sinusoidal dependence on the combined rotation angles, but systematic deviations appear as pronounced peaks and variations in certain configurations. Long-term monitoring over twenty minutes shows correlated fluctuations on both sides in individual detection outcomes of up to 25%, while the total photon flux remains constant, indicating that these deviations originate from slow intrinsic changes in the generated quantum state. These temporal fluctuations can reduce the effective time window over which optimal polarization and phase alignment is maintained, highlighting the importance of implementing real-time compensation or feedback mechanisms in experiments requiring high-fidelity entanglement over extended durations. Our results provide insight into the stability limits of entangled photon sources and underscore the importance of accounting for temporal fluctuations in precision entanglement experiments.
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