Direct measurement of concurrence for atomic two-qubit pure states
Guillermo Romero, C. López, F. Lastra, E. Solano, J. C. Retamal · Physical Review A · 2007
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 three-dimensional microwave cavities and trapped ion systems.