Robust Entanglement Generation in Bipartite Quantum Systems Using Optimal Control

TL;DR

This paper develops a quantum optimal control method to generate high-fidelity entanglement in bipartite systems, using Pontryagin's principle to design control fields that maximize entanglement measures like concurrence.

Contribution

It introduces a novel control framework based on Pontryagin's Minimum Principle for robust entanglement generation in two-qubit systems, validated through numerical simulations.

Findings

Effective control strategies achieve high concurrence at fixed times.

Switching-based controls enhance robustness of entanglement.

Numerical results confirm the method's practical potential.

Abstract

Quantum entanglement is a key resource for quantum technologies, yet its efficient and high-fidelity generation remains a challenge due to the complexity of quantum dynamics. This paper presents a quantum optimal control framework to maximize bipartite entanglement within a fixed time horizon, under bounded control inputs. By leveraging Pontryagin's Minimum Principle, we derive a set of necessary conditions that guide the design of time-dependent control fields to steer a two-qubit system toward maximally entangled Bell states. The entanglement is quantified using concurrence, and the control objective is formulated as maximizing this measure at the terminal time. Our approach is validated through numerical simulations of Liouville-von Neumann dynamics. The results demonstrate the effectiveness of switching-based control strategies in achieving robust entanglement, offering insights into practical implementations of quantum control for entanglement generation in quantum networks.