Potential multiparticle entanglement measure - art. no. 044301

In this Brief Report we discuss entanglement of multiparticle quantum syste ms. We propose a potential measure of a type of entanglement of pure states of n qubits, the n-tangle. For a system of two qubits the n-tangle is equa l to the square of the concurrence, and for systems of three qubits it is e qual to the "residual entanglement." We show that the n -tangle is also equ al to a generalization of the concurrence squared for even n, and use this fact to prove that the n-tangle is an entanglement monotone. However, the n -tangle is undefined for odd n>3. Finally, we propose a measure related to the n-tangle for mixed-state systems of n qubits, and find an analytical fo rmula for this measure for even n.