Finite-Time Disentanglement Via Spontaneous Emission

We show that under the influence of pure vacuum noise two entangled qubits become completely disentangled in a finite-time, and in a specific example we find the time to be given by $\ln (\frac{2+\sqrt{2}}{2})$ times the usual spontaneous lifetime.

Figure 1

Schematic illustration of a setup in which two atoms are located inside two spatially separated cavities A and B. The two atoms are initially entangled but have no direct interaction afterwards.

Figure 2

The entanglement decay via spontaneous emission starting from the initially entangled states (31) with $a$ between zero and 1, $d=1-a$ and $b=c=z=1$. Finite-time complete disentanglement takes place for $a>1/3$, and when $a\le 1/3$ disentanglement of the initial state is only completed asymptotically.