LASER PHYSICS; RESEARCH CONDUCTED AT N. SAHAKYAN AND CO-AUTHORS HAS PROVIDED NEW INFORMATION ABOUT LASER PHYSICS
Physics Week
May 4, 2010
"In the framework of a basic semiclassical time-dependent nonlinear
two-state problem, we study the weak coupling limit of the nonlinear
Landau-Zener transition at coherent photo- and magneto-association
of an atomic Bose-Einstein condensate. Using an exact third-order
nonlinear differential equation for the molecular state probability,
we develop a variational approach which enables us to construct
an accurate analytic approximation describing time dynamics of
the coupled atom-molecular system for the case of weak coupling,"
scientists writing in the journal Laser Physics report.
"The approximation is written in terms of the solution to an
auxiliary linear Landau-Zener problem with some effective Landau-Zener
parameter. The dependence of this effective parameter on the input
Landau-Zener parameter is found to be unexpected: as the generic
Landau-Zener parameter increases, the effective Landau-Zener parameter
first monotonically increases (starting from zero), reaches its
maximal value and then monotonically decreases again reaching zero
at some point. The constructed approximation quantitatively well
describes many characteristics of the time dynamics of the system,
in particular, it provides a highly accurate formula for the final
transition probability to the molecular state. The present result for
the final transition probability improves the accuracy of the previous
approximation by Ishkhanyan et al. [Phys. Rev. A 69, 043612 (2004); J.
Phys," wrote N. Sahakyan and colleagues.
The researchers concluded: "A 38, 3505 (2005)] by order of magnitude."
Sahakyan and colleagues published their study in Laser Physics (Weak
Coupling Regime of the Landau-Zener Transition for Association of an
Atomic Bose-Einstein Condensate. Laser Physics, 2010;20(1):291-297).
Additional information can be obtained by contacting N. Sahakyan,
NAS Armenia, Inst Phys Res, Ashtarak 0203 2, Armenia.