Decoherence and Entanglement Dynamics of Coupled Qubits
Abstract
We study the entanglement dynamics and relaxation properties of a system of two interacting qubits in the two cases (I) two independent bosonic baths and (II) one common bath, at temperature T. The entanglement dynamics is studied in terms of the concurrence C (t) between the two spins and of the von Neumann entropy S(t) with respect to the bath, as a function of time. We prove that the system does thermalize. In the case (II) of a single bath, the existence of a decoherence-free (DFS) subspace makes entanglement dynamics very rich. We show that when the system is initially in a state with a component in the DFS the relaxation time is surprisingly long, showing the existence of semi-decoherence free subspaces. The equilibrium state in this case is not the Gibbs state. The entanglement dynamics for the single bath case is also studied as a function of temperature, coupling strength with the environment and strength of tunneling coupling. The case of the mixed state is finally shown and discussed.
Cite
@article{arxiv.0807.1987,
title = {Decoherence and Entanglement Dynamics of Coupled Qubits},
author = {G. Campagnano and A. Hamma and U. Weiss},
journal= {arXiv preprint arXiv:0807.1987},
year = {2017}
}
Comments
improved version with all the details and study in function of temperature, coupling strengths and the study of the mixed state case