Mechanism of entanglement preservation

TL;DR

This paper investigates how bound states and non-Markovian effects influence entanglement preservation between two qubits interacting with reservoirs, offering insights for quantum information stability.

Contribution

It reveals the combined role of bound states and non-Markovian effects in steady-state entanglement preservation, unifying different scenarios in a single framework.

Findings

Bound states and non-Markovian effects are crucial for entanglement preservation.

Neglecting non-Markovian effects leads to entanglement sudden death.

Strong non-Markovian effects without bound states cause entanglement revival.

Abstract

We study the entanglement preservation of two qubits locally interacting with their reservoirs. We show that the existence of a bound state of the qubit and its reservoir and the non-Markovian effect are two essential ingredients and their interplay plays a crucial role in preserving the entanglement in the steady state. When the non-Markovian effect is neglected, the entanglement sudden death (ESD) is reproduced. On the other hand, when the non-Markovian is significantly strong but the bound state is absent, the phenomenon of the ESD and its revival is recovered. Our formulation presents a unified picture about the entanglement preservation and provides a clear clue on how to preserve the entanglement in quantum information processing.