Heidelberg 1999 – scientific programme

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Q: Quantenoptik

Q 37: Poster: Quanteneffekte

Q 37.19: Poster

Thursday, March 18, 1999, 16:30–18:30, PH

Laser-driven population transfer in four-level atoms; Consequences of non-Abelian geometrical adiabatic phase factors — •R. G. Unanyan^1,2, B. W. Shore^1,3, and K. Bergmann¹ — ¹Fachbereich Physik der Universit"at Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern — ²Institute for Physical Research of Armenian National Academy of Sicences, Ashtarak-2, 378410, Armenia — ³Lawrence Livermore National Labortory, Livermore CA 94550, USA

We analyze the influence of three pulsed laser fields interacting with a four-state atomic system for which there occur two degenerate population-trapping dressed states. We present a simple expression for the geometrical phase [1] acquired by such an atom during a stimulated Raman adiabatic passage (STIRAP) [2]. There is interest in such a possibility not only for practical application to atom optics. The value of the geometrical phase γ =∫BdS, B= R/R where R=(Ω₁,Ω ₂,Ω ₃) is the vector in parametric space and Ω_i are Rabi frequencies of the laser fields, and dS denotes the area element in the R space. The geometrical phase can be changed by changing the relative delay of the pulses and can be measured by observing population in atomic states. We show that when the pump and Stokes pulses are properly timed high population transfer from the initial state to target state is achieved. In the adiabatic limit the robustness of population transfer is equivalent to that of STIRAP.

[1] M. Berry, Proc. R. Soc. Lond. A 392, 45 (1984)

[2] K. Bergmann, et al. Rev. Mod. Physics, 70, 1003, (1998)