Entanglement Measure-Based Sliding Mode Control for Quantum State Preparation

Entangled states are fundamental to quantum information processing. However, many existing quantum control methods rely on predefined target states, limiting their flexibility in accommodating diverse entanglement structures. This article introduces a sliding mode control framework that utilizes an entanglement measure as the sliding surface, enabling the generation of entangled states without specifying a fixed target. By adjusting the desired entanglement level, the proposed method can generate a wide range of states, including both bipartite and multipartite configurations, as well as pure and mixed states. Since the entanglement measure is scalar-valued, the resulting control law is inherently independent of the number of subsystems—an important advantage of the proposed approach. Among various entangled states, maximally entangled states (MESs) are of particular interest. Lyapunov stability of the control scheme is established, and numerical simulations confirm its effectiveness in robustly generating MESs in both bipartite and multipartite systems.