  We apply the continuous variable approach to study entangled dynamics of
coupled harmonic oscillators interacting with a thermal reservoir and to a
deterministic creation of entanglement in an atomic ensemble located inside a
high-Q ring cavity. In the case of harmonic oscillators, we show that a
suitable unitary transformation of the position and momentum operators
transforms the system to a set of independent harmonic oscillators with only
one of them coupled to the reservoir. Working in the Wigner representation of
the density operator, we find that the covariance matrix has a block diagonal
form of smaller size matrices. This simple property allows to treat the problem
to some extend analytically. We analyze the time evolution of an initial
entanglement and find that the entanglement can persists for long times due to
presence of constants of motion for the covariance matrix elements. In the case
of an atomic ensemble located inside the cavity, the attention is focused on
creation of one and two-mode continuous variable entangled states from the
vacuum by applying laser pulses of a suitably adjusted amplitudes and phases.
The pulses together with the cavity dissipation prepare the collective modes of
the atomic ensemble in a desired entangled state.
