Decoherence effects in interacting qubits under the influence of various environments

TL;DR

This paper investigates how environmental interactions influence entanglement dynamics in two interacting qubits, revealing periodic disentanglement and entanglement phenomena that precede entanglement sudden death across various models.

Contribution

It provides analytical results showing the generic occurrence of periodic entanglement behavior and its relation to entanglement sudden death in different environmental models.

Findings

Periodic entanglement and disentanglement occur before ESD.

Disentanglement persists for finite times due to environmental effects.

Phenomena are observed across various environmental models.

Abstract

We study competition between the dissipative and coherent effects in the entanglement dynamics of two qubits. The coherent interactions are needed for designing logic gate operations with systems like ion traps, semicondutor quantum dots and atoms. We show that the interactions lead to a phenomenon of periodic disentanglement and entanglement between the qubits. The disentanglement is primarily caused by environmental perturbations. The qubits are seen to remain disentangled for a finite time before getting entangled again. We find that the phenomenon is generic and occurs for wide variety of models of the environment. We present analytical results for the time dependence of concurrence for all the models. The periodic disentanglement and entanglement behavior is seen to be precursor to the sudden death of entanglement (ESD) and can happen, for environments which do not show ESD for noninteracting qubits. Further we also find that this phenomenon can even lead to delayed death of entanglement for correlated environments.