Pre-management of Disentanglement

TL;DR

This paper introduces a method to pre-manage entanglement in quantum systems by analyzing initial parameters and decay behaviors to prevent crossing a critical disentanglement threshold during evolution.

Contribution

It develops phase diagrams for entanglement preservation in two-qubit systems considering non-exponential decay and various relaxation processes.

Findings

Disentanglement can be pre-managed through initial parameters.

Phase diagrams illustrate entanglement preservation conditions.

Non-smooth decay behaviors are analyzed for better control.

Abstract

We define threshold disentanglement (TD) as the level above which entanglement must be maintained for later use and calculate the values of quantum system parameters at $t=0$ that will ensure that the threshold is not crossed in a specified time. An important issue is the possibility of non-smooth, typically non-exponential, decay of entanglement into the state of complete disentanglement (CD). Given a specified operation time $\tau$, we determine phase diagrams showing entanglement preservation during the evolution of a generic two-qubit mixed state as a function of selected initial parameters such as concurrence and excitation probabilities. In other words, disentanglement can be pre-managed through these parameters. Three common relaxation processes - amplitude, phase and depolarization - are considered.