Quantum entanglement plays a fundamental role in quantum computation and quantum communication. Feedback control has been widely used in stochastic quantum systems to generate given entangled states since it has good robustness, where the time required to compute filter states and conduct filter-based control usually cannot be ignored in many practical applications. This paper designed two control strategies based on the Lyapunov method to prepare a class of entangled states for qubit systems with a constant delay time. The first one is bang–bang-like control strategy, which has a simple form with switching between a constant value and zero, the stability of which is proved. Another control strategy is switching Lyapunov control, where a constant delay time is introduced in the filter-based feedback control law to compensate for the computation time. Numerical results on a two-qubit system illustrate the effectiveness of these two proposed control strategies.

量子纠缠在量子计算和量子通信中起着基本作用。由于反馈控制具有良好的鲁棒性，因此它已在随机量子系统中广泛用于生成给定的纠缠态，在许多实际应用中，计算滤波器状态和进行基于滤波器的控制所需的时间通常不能忽略。本文基于李雅普诺夫方法设计了两种控制策略，为具有恒定延迟时间的量子比特系统准备了一类纠缠态。第一个是类bang-bang类控制策略，它具有在常数和零之间切换的简单形式，并证明了其稳定性。另一种控制策略是切换Lyapunov控制，在基于滤波器的反馈控制律中引入了恒定的延迟时间以补偿计算时间。两量子位系统上的数值结果说明了这两种建议的控制策略的有效性。