Determining the Dynamics of Entanglement
O. Jiménez Farías,1,2
C. Lombard Latune,1,3
S. P. Walborn,1
L. Davidovich,1
P. H. Souto Ribeiro1,*
The estimation of the entanglement of multipartite systems undergoing
decoherence is important for assessing the robustness of quantum
information processes. It usually requires access to the final
state and its full reconstruction through quantum tomography.
General dynamical laws may simplify this task. We found that
when one of the parties of an initially entangled two-qubit
system is subject to a noisy channel, a single universal curve
describes the dynamics of entanglement for both pure and mixed
states, including those for which entanglement suddenly disappears.
Our result, which is experimentally demonstrated using a linear
optics setup, leads to a direct and efficient determination
of entanglement through the knowledge of the initial state and
single-party process tomography alone, foregoing the need to
reconstruct the final state.
2 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (UNAM), Apdo. Postal 70-543, México 04510 D.F.
3 École Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
* To whom correspondence should be addressed. E-mail: phsr{at}if.ufrj.br
