  We study the effects of losses on the entanglement created between two
separate atomic gases by optical probing and homodyne detection of the
transmitted light. The system is well-described in the Gaussian state
formulation. Analytical results quantifying the degree of entanglement between
the two gases are derived and compared with the entanglement in a pair of light
pulses generated by an EPR source. For low (high) transmission losses the
highest degree of entanglement is obtained by probing with squeezed
(antisqueezed) light. In an asymmetric setup where light is only sent one way
through the atomic samples, we find that the logarithmic negativity of
entanglement attains a constant value $-\log_2(N)$ with $N=1/3$ irrespectively
of the loss along the transmission line.
