  For two qubits in a pure state there exists a one-to-one relation between the
entanglement measure (the concurrence ${\cal C}$) and the maximal violation
${\cal M}$ of a Bell inequality. No such relation exists for the three-qubit
analogue of ${\cal C}$ (the tangle $\tau$), but we have found that numerical
data is consistent with a simple set of upper and lower bounds for $\tau$ given
${\cal M}$. The bounds on $\tau$ become tighter with increasing ${\cal M}$, so
they are of practical use. The Svetlichny form of the Bell inequality gives
tighter bounds than the Mermin form. We show that the bounds can be tightened
further if the tangle is replaced by an entanglement monotone that can identify
both the W state and the Greenberger-Horne-Zeilinger state.

Quantum Physics