Negative entanglement measure, and what it implies.

In this paper, we extract from concurrence its variable part, denoted Λ, a function of density matrix ρ, either positive or negative. We use it to investigate entanglement dynamics of two isolated but initially entangled qubits, each coupled to its own environment. In particular, we show that it can signal whether the disentanglement of an entangled state occurs in a finite time. [ABSTRACT FROM AUTHOR]