  We propose and study a method for detecting ground-state entanglement in a
chain of trapped ions, which realizes a suggested scheme for detecting vacuum
entanglement in quantum field theory. We show that the entanglement between
single ions or groups of ions can be swapped to the internal levels of two ions
by sending laser pulses that couple the internal and motional degrees of
freedom. This allows to entangle two ions without actually doing gates. A proof
of principle of the effect can be realized with two trapped ions and is
feasible with current technology.
