AI 中文总结
本研究提出一种构造性框架，通过混合不同参数的振幅阻尼与反阻尼信道生成更广泛的相位协变动力学，可独立控制收缩与平移，能减少与理想无噪声演化的偏差，适用于噪声控制等量子信息处理场景。
AI 中文摘要
非幺正噪声是开放量子系统的基本特征，它支配能量交换并诱导Bloch球上的态平移。这类平移对态制备和信道容量等任务有用，但在量子信息处理中，尤其是纠错时，通常更偏好无平移的幺正动力学。相位协变动力学是涵盖量子比特系统中耗散、激发和退相位过程的通用框架；然而，常用模型如广义振幅阻尼（GAD）信道对这些特征的控制有限。本工作中，我们提出一种构造性框架，通过混合具有不等衰减参数和随时间变化的混合概率的振幅阻尼与反阻尼信道，生成更广泛类别的相位协变动力学。该方法可独立控制收缩与平移，允许在非幺正和幺正区域间连续调节，并产生GAD信道中不存在的有效退相位贡献。为表征这些动力学，我们采用P-可分性的通用定理，表明通过在适当选择的希尔伯特空间基中评估该定理，可将其用于构造，从而为幺正和非幺正情况导出简化条件。该框架涵盖多种行为，包括CP-可分、P-可分但非CP-可分，以及非P-可分动力学。我们进一步表明，适当的混合可减少与理想无噪声演化的偏差，且这种改进在将动力学调节至幺正区域后仍持续存在。我们的结果提供了一种灵活的方法，用于构造超越标准热模型的开放系统动力学，在噪声控制和量子信息处理中具有潜在应用。
英文摘要
Non-unital noise is a fundamental feature of open quantum systems, governing energy exchange and inducing state translations on the Bloch sphere. While such translations can be useful for tasks such as state preparation and channel capacity, unital dynamics where no translation occurs are often preferred in quantum information processing, particularly for error correction. Phase-covariant dynamics provide a general framework encompassing dissipation, excitation, and dephasing processes in qubit systems; however, commonly used models such as the generalized amplitude damping (GAD) channel offer only limited control over these features. In this work, we present a constructive framework for generating a broader class of phase-covariant dynamics by mixing amplitude-damping and anti-damping channels with unequal decay parameters and time-dependent mixing probabilities. This approach enables independent control over contraction and translation, allows continuous tuning between non-unital and unital regimes, and yields an effective dephasing contribution absent in GAD. To characterize these dynamics, we employ the general theorem for P-divisibility and show that it can be used constructively by evaluating it in suitably chosen Hilbert space bases, leading to simplified conditions for both unital and non-unital cases. The framework captures a wide range of behaviors, including CP-divisible, P-divisible but not CP-divisible, and non-P-divisible dynamics. We further show that appropriate mixing can reduce the deviation from the ideal noiseless evolution and that such improvement persists even after tuning the dynamics to the unital regime. Our results provide a flexible approach to engineering open system dynamics beyond standard thermal models, with potential applications in noise control and quantum information processing.
Comments20 pages, 7 figures
