Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 50: Atomic systems in external fields II

A 50.2: Vortrag

Freitag, 22. März 2013, 14:15–14:30, B 302

Measurements of the dynamic and Berry phases in Rb superposition states — •Carl Basler — Department of Molecular and Optical Physics, Universität Freiburg

We study the transient response of the refractive index to changes of the magnetic field vector under conditions of electromagnetically-induced transparency. This is an extension of our recent work, FM et al. PR A 85, 013820 (2012) where the dynamic response to frequency changes was explored. Under EIT conditions the superposition state Ψ =(|1⟩ − e^iη |2⟩)/√2 is called dark state and is barred from fluorescence. This state develops by spontaneous emission in the presence of two phase-stable laser fields E_j(ω_j , φ_j). The dark state phase fulfils the requirement η = φ₁ −φ₂ and is thus sensitive to the laser phases. When the dark state has formed and the lasers are suddenly detuned from EIT resonance the atoms undergo Rabi floppings between dark and bright state.

When changing the magnetic field, the lasers are also detuned from resonance due to Zeeman shifts and the dark state atoms pick up a dynamic phase. When the magnetic field is not changed in strength but rotated in space the system acquires a Berry phase. We show measurements of the dynamic phase and the Berry phase of Rb-atoms in a buffered gas cell at room temperature.