  We propose a general scheme to measure the concurrence of an arbitrary
two-qubit pure state in atomic systems. The protocol is based on one- and
two-qubit operations acting on two available copies of the bipartite system,
and followed by a global qubit readout. We show that it is possible to encode
the concurrence in the probability of finding all atomic qubits in the ground
state. Two possible scenarios are considered: atoms crossing 3D microwave
cavities and trapped ion systems.
