Quantum Optics Seminar by Dr. Irina Novikova – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Seminar by Dr. Irina Novikova

Electromagnetically induced transparency and related two-photon Raman processes has been proposed and used for wide range of applications. However, most of these applications require an atomic ensemble of sufficiently high optical depth in order to achieve optimal performance. We investigate this regime using stored light technique, that has been investigated for EIT quantum memory applications.

At high optical depth, a simplified treatment of EIT-based quantum memory in a single-A system is incomplete, and fails to properly describe signal pulse propagation and storage, and inevitable presence of resonance four-wave mixing (FWM) in a double-A system has to be taken into account. Under EIT/FWM conditions ground-state spin coherence is determined by a combination of signal and Stokes fields, and the dark state polariton description of the signal pulse propagation has to be modified. We found that for low and moderate optical depth of atomic ensemble, the contribution of FWM is negligible, and it seems to be possible to store and retrieve a combination of signal and Stokes fields, even though each individual field is not preserved. However, for higher optical depth, this treatment fails due to additional gain or absorption in Stokes field.