  The atom-photon entanglement of dressed atom and its spontaneous emission in
a Double-Lambda closed-loop atomic system is studied in multi-photon resonance
condition. It is shown that, even in the absence of quantum interference due to
the spontaneous emission, the von Neumann entropy is phase-sensitive and it can
be controlled by either intensity or relative phase of the applied fields. It
is demonstrated that, for the special case of Rabi frequency of the applied
fields the system is maximally entangled. Moreover, the open-loop configuration
is considered and it is shown that the degree of entanglement measure (DEM) can
be controlled by intensity of the applied fields. Furthermore, in
electromagnetically induced transparency condition, the system is disentangled.
Such a system can be used for quantum information processing via entanglement
using optical switching.
