Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 39: Poster: Atomic systems in external fields

A 39.7: Poster

Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof

On the response of electromagnetically-induced transparency to laser phase changes — Carl Basler, •Katrin Reininger, Stephan Welte, and Jannis Seyfried — Universität Freiburg

We study the transient response of the refractive index to changes of the phase of the laser field under conditions of electromagnetically induced transparency. This is an extension of recent work in our group, FM et al. PR A 85, 013820 (2012) where the dynamic response to frequency changes was explored. Under EIT conditions the quantum superposition state Ψ = |1> − e^iη|2>, called dark state, develops by spontaneous emission in the presence of two phase-stable laser fields E_j(ω_j,ϕ_j). The dark state phase fulfills the requirement η=ϕ₁−ϕ₂ and is thus sensitive to the laser phase. If under EIT conditions the relative phase of the laser fields is changed by π the dark state superposition instantly becomes bright. More intricate is the behavior under conditions near EIT resonance. Here the dynamic response shows instant as well as slow components which mirror the interplay between rapid and slow coherences in the density matrix. With phase jumps of short duration we can determine the relative phase between the dark state and the laser field in a minimally destructive way, we can measure the absolute depth of the dark resonance and the absolute detuning from EIT resonance without detuning the lasers.