Proceedings Article | 3 February 2009
Proc. SPIE. 7226, Advances in Slow and Fast Light II
KEYWORDS: Superposition, Digital signal processing, Transparency, Chemical species, Control systems, Signal processing, Process control, Electromagnetism, Radio propagation, Beam controllers
In a Λ-type atomic system with electromagnetically-induced transparency, we probe the fidelity of the storage
and retrieval of an electromagnetic signal, as the control laser field is varied with time. We study numerically the
adiabatic transfer problem for an isolated atom, and show that for a weak signal, even the slowest variations of
the control field take the system out of the dark state, which is a coherent superposition of the two lower levels
of the Λ system. Following this, we incorporate the effect of dissipation on system dynamics by allowing for
spontaneous decay of the system to the lower levels in a wavefunction approach. We conclude that dissipation
definitely aids the retrieval process but not so much the storage. Further, for storing the signal, the control field
should be switched off as slowly as possible, but while retrieving it, the faster we switch on the control field, the
better the signal is retrieved. Also, for a given system there is an optimal control power for the best retrieval.
Our results find partial support in the reported experimental observations.
