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中国物理学会期刊

三能级系统熵不确定关系动力学的反馈调控

CSTR: 32037.14.aps.75.20251342

Feedback control of e entropic uncertainty relation dynamics in three-level system

CSTR: 32037.14.aps.75.20251342
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  • 量子信息科学中, 不确定性原理已从其基础性限制演变为一种可操纵的核心资源, 为量子保密通信的安全性和量子计算的优越性提供了根本保障. 本文研究量子反馈控制下两体三能级系统的量子存储支撑熵不确定关系, 利用量子反馈控制调控噪声环境中的熵不确定度及其下限. 分别选取激发态和最大纠缠态作为系统的初态, 通过调节反馈参数发现: 反馈控制可以抑制环境噪声, 显著降低熵不确定度及其下限; 此外, 通过数值计算, 我们找到了两种初态下降低熵不确定度及其下限的最优反馈参数; 发现最优反馈控制下, 系统初始的最大纠缠态演化为最大经典关联态, 测量粒子与存储粒子间的经典关联降低了系统稳态的熵不确定度; 最后分析了熵不确定性与系统纯度之间的关系, 发现熵不确定度及其下限的演化与系统纯度呈现负相关, 为通过量子态纯化降低不确定性指明了方向.

     

    Uncertainty principle, a cornerstone of quantum mechanics, has evolved from a fundamental limitation into a manageable resource in quantum information science. Precise control over quantum uncertainty is crucial for ensuring the security of quantum cryptography and the advantage of quantum computation. In this work, we investigate the control of the quantum-memory-assisted entropic uncertainty relation in a noisy two-particle qutrit system under quantum feedback control. In our model, Bob prepares a system AB composed of two V-type three-level atoms and sends atom A to Alice. Atom A interacts with a bimodal dissipative cavity. To suppress decoherence, a photodetector is used to monitor the dissipative cavity. Once a photon is detected, a local quantum feedback control is applied to atom A. Meanwhile, Bob's atom B is assumed to be isolated from the noisy environment. The uncertainty is quantified by two incompatible observables, S_x and S_z, corresponding to the spin-1 components.
    We analyze the evolution of the entropic uncertainty and its lower bound, with the system initialized in two distinct states: an excited state and a maximally entangled state. Our findings demonstrate that the appropriate quantum feedback control can significantly suppress decoherence, leading to a marked reduction in both the entropic uncertainty and its lower bound. Through numerical simulations, we identify the optimal feedback strength for minimizing the entropic uncertainty and its lower bound to be \textπ/2 for both initial states. By examining the system's steady-state behavior after prolonged evolution, we find a key insight: under optimal feedback, the initial maximally entangled state evolves into a state with maximal classical correlation. Although no quantum correlation exists in this steady state, the strong classical correlation provides Bob with partial information about atom A, thereby enhancing his prediction accuracy for the measurement outcomes and leading to the observed reduction in the entropic uncertainty. Additionally, we explore the dynamics of the system's purity. The results show a clear negative correlation, indicating that the reduction in entropic uncertainty is directly attributable to the purification of the system effected by the feedback control. In conclusion, the quantum feedback control established in this work may serve as an effective theoretical protocol for suppressing the entropic uncertainty in realistic noisy environments. It provides a viable pathway for manipulating quantum uncertainty to enhance the robustness and performance of quantum information processing tasks.

     

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