2 research outputs found
Steady state behaviour in atomic three-level lambda and ladder systems with incoherent population pumping
The steady state in three-level lambda and ladder systems is studied. It is
well-known that in a lambda system this steady state is the coherent population
trapping state, independent of the presence of spontaneous emission. In
contrast, the steady state in a ladder system is in general not stable against
radiative decay and exhibits a minimum in the population of the ground state.
It is shown that incoherent population pumping destroys the stability of the
coherent population trapping state in the lambda system and suppresses a
previously discovered sharp dip in the steady state response. In the ladder
system the observed minimum disappears in the presence of an incoherent pump on
the upper transition.Comment: 4 pages, RevTex, 5 figures, to appear in Phys. Rev.
Temporal build-up of electromagnetically induced transparency and absorption resonances in degenerate two-level transitions
The temporal evolution of electromagnetically induced transparency (EIT) and
absorption (EIA) coherence resonances in pump-probe spectroscopy of degenerate
two-level atomic transition is studied for light intensities below saturation.
Analytical expression for the transient absorption spectra are given for simple
model systems and a model for the calculation of the time dependent response of
realistic atomic transitions, where the Zeeman degeneracy is fully accounted
for, is presented. EIT and EIA resonances have a similar (opposite sign) time
dependent lineshape, however, the EIA evolution is slower and thus narrower
lines are observed for long interaction time. Qualitative agreement with the
theoretical predictions is obtained for the transient probe absorption on the
line in an atomic beam experiment.Comment: 10 pages, 9 figures. Submitted to Phys. Rev.