The decoherence effects experienced by the qubits of a quantum processor are generally characterized using the amplitude damping time (T₁) and the dephasing time (T₂). Quantum channel models that exist at the time of writing assume that these parameters are fixed and invariant. However, recent experimental studies have shown that they exhibit a time-varying (TV) behaviour. These time-dependant fluctuations of T₁ and T₂, which become even more pronounced in the case of superconducting qubits, imply that conventional static quantum channel models do not capture the noise dynamics experienced by realistic qubits with sufficient precision. In this article, we study how the fluctuations of T₁ and T₂ can be included in quantum channel models. We propose the idea of time-varying quantum channel (TVQC) models, and we show how they provide a more realistic portrayal of decoherence effects than static models in some instances. We also discuss the divergence that exists between TVQCs and their static counterparts by means of a metric known as the diamond norm. In many circumstances this divergence can be significant, which indicates that the time-dependent nature of decoherence must be considered, in order to construct models that capture the real nature of quantum devices.

量子处理器的量子位所经历的退相干效应通常使用振幅阻尼时间 ( T ₁ ) 和移相时间 ( T ₂ ) 来表征。在撰写本文时存在的量子通道模型假设这些参数是固定不变的。然而，最近的实验研究表明，它们表现出时变 (TV) 行为。T ₁和T _{2 的}这些随时间变化的波动，在超导量子位的情况下变得更加明显，这意味着传统的静态量子通道模型不能以足够的精度捕捉现实量子位所经历的噪声动力学。在本文中，我们研究了T ₁和T ₂的波动如何可以包含在量子信道模型中。我们提出了时变量子信道 (TVQC) 模型的想法，并展示了它们如何在某些情况下比静态模型更真实地描绘退相干效应。我们还通过称为菱形范数的度量来讨论 TVQC 与其静态对应物之间存在的差异。在许多情况下，这种差异可能很大，这表明必须考虑退相干的时间相关性，以便构建捕捉量子设备真实性质的模型。