Generation of single photons with highly tunable wave shape from a cold atomic quantum memory

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We report on a single photon source with highly tunable photon shape based on a cold ensemble of Rubidium atoms.

• We follow the DLCZ scheme to implement an emissive quantum memory, which can be operated as a photon pair source with controllable delay.
• We find that the temporal wave shape of the emitted read photon can be precisely controlled by changing the shape of the driving read pulse.
• We generate photons with temporal durations varying over three orders of magnitude up to 10 {\mu}s without a significant change of the read-out efficiency.