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Generation of Narrowband Quantum Light for Interaction with Rb Atoms

I will present two quantum light sources based on parametric down conversion in a resonant cavity pumped by a diode laser for application to measurements of atomic degrees of freedom. These sources present a narrow-band spectrum (~7 MHz) tunable within the D1 line of Rb.
The first source is based on type-I phase matching and produces resonant light presenting 3 dB of polarization squeezing that improves quantum-noise-limited polarization rotation measurements.
The second one is based on type-II phase matching, producing pairs of orthogonally polarized photons. The cavity presents  ~600 longitudinal modes. The degenerate Rb resonant mode is selected using a narrow-band filter based on optically induced dichroism in a Rb vapor. The result is a narrow-band polarization 2-N00N state which, in the ideal case,  allows to achieve Heisenberg resolution in phase measurement.