  Decoherence is well understood, in contrast to disentanglement. According to
common lore, irreversible coupling to a dissipative environment is the
mechanism for loss of entanglement. Here, we show that, on the contrary,
disentanglement can in fact occur at large enough temperatures $T$ even for
vanishingly small dissipation (as we have shown previously for decoherence).
However, whereas the effect of $T$ on decoherence increases exponentially with
time, the effect of $T$ on disentanglement is constant for all times,
reflecting a fundamental difference between the two phenomena. Also, the
possibility of disentanglement at a particular $T$ increases with decreasing
initial entanglement.
