  Previous work on Bell's inequality realised in the laboratory has used
entangled photons. Here we describe how entangled atoms can violate Bell's
inequality, and how these violations can be measured with a very high detection
efficiency. We first discuss a simple scheme based on two-level atoms inside a
cavity to prepare the entangled state. We then discuss a scheme using
four-level atoms, which requires a parameter regime much easier to access
experimentally using current technology. As opposed to other schemes, our
proposal relies on the presence of finite decay rates and its implementation
should therefore be much less demanding.
