  We investigate three superconducting flux qubits coupled in a loop. In this
setup, tripartite entanglement can be created in a natural, controllable, and
stable way. Both generic kinds of tripartite entanglement -the W type as well
as the GHZ type entanglement- can be identified among the eigenstates. We also
discuss the violation of Bell inequalities in this system and show the impact
of a limited measurement fidelity on the detection of entanglement and quantum
nonlocality.
