Evolution of pairwise entanglement in a coupled n-body system (6 pages)

Henry L. Haselgrove

Liang Qiu, An Min Wang, Xiao Qiang Su

Anubhav Kumar Srivastava, Guillem Müller-Rigat, Maciej Lewenstein +1 more

Gavin K. Brennen

Preparing many body entangled states efficiently using available interactions is a challenging task. One solution may be to couple a system collectively with a probe that leaves residual entanglement in the system. We investigate the entanglement produced between two possibly distant qubits 1 and 2 that interact locally with a third qubit 3 under unitary evolution generated by pairwise Hamiltonians. For the case where the Hamiltonians commute, relevant to certain quantum nondemolition measurements, the entanglement between qubits 1 and 2 is calculated explicitly for several classes of initial states and compared with the case of noncommuting interaction Hamiltonians. This analysis can be helpful to identify preferable physical system interactions for entangled state synthesis.

Carlos Pineda, T. H. Seligman

We study the exact evolution of two noninteracting qubits, initially in a Bell state, in the presence of an environment, modeled by a kicked Ising spin chain. Dynamics of this model range from integrable to chaotic and we can handle numerics for a large number of qubits. We find that the entanglement (as measured by concurrence) of the two qubits has a close relation to the purity of the pair, and closely follows an analytic relation derived for Werner states. As a collateral result we find that an integrable environment causes quadratic decay of concurrence as well as of purity, while a chaotic environment causes linear decay. Both quantities display recurrences in an integrable environment.

J. W. Clark, Hessam Habibian, Aikaterini Mandilara +1 more