Eur. Phys. J. D 46, 537-543 (2008)
https://doi.org/10.1140/epjd/e2007-00333-0

Synthesis of maximally entangled mixed states and disentanglement in coupled Josephson charge qubits

Mathematics Department, Faculty of Science, Sohag University, 82524 Sohag, Egypt

Corresponding author: ^a abdelatyquantum@yahoo.co.uk

Received: 13 October 2007
Revised: 31 October 2007
Published online: 14 December 2007

Abstract

We analyze a controllable generation of maximally entangled mixed states of a circuit containing two-coupled superconducting charge qubits. Each qubit is based on a Cooper pair box connected to a reservoir electrode through a Josephson junction. Illustrative variational calculations were performed to demonstrate the effect on the two-qubits entanglement. At sufficiently deviation between the Josephson energies of the qubits and/or strong coupling regime, maximally entangled mixed states at certain instances of time is synthesized. We show that entanglement has an interesting subsequent time evolution, including the sudden death effect. This enables us to completely characterize the phenomenon of entanglement sharing in the coupling of two superconducting charge qubits, a system of both theoretical and experimental interest.