Observation of time correlation function of multimode two-photon pairs on a rubidium D2 line
Abstract
We report the generation of a type-I multimode two-photon state on a rubidium D2 line (780 nm) using periodically poled KTiOPO4 crystals. With a degenerate optical parametric oscillator far below threshold, we observe an oscillatory correlation function, the cross-correlation between two photons shows a cavity bandwidth of about 7.8 MHz. We also use a Fabry-Perot etalon to filter its most longitudinal modes and observe its time correlation function. The experimental data are well fitted to theoretical curves. This system could be utilized for demonstrating storage and retrieval of narrowband photons in Rb atomic ensembles, which is important for long-distance quantum communication.
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