Time-varying quantum channel models for superconducting qubits
Time-varying quantum channel models for superconducting qubits
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DOI：
10.1038/s41534-021-00448-5
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发表时间：
2021-07
影响因子：
7.6
通讯作者：
Josu Etxezarreta Martinez;Patricio Fuentes;P. Crespo;J. Garcia-Frías
中科院分区：
文献类型：
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作者：
Josu Etxezarreta Martinez;Patricio Fuentes;P. Crespo;J. Garcia-Frías
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（T1）和失相时间（T2）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。T1和T2的这些随时间变化的波动，在超导量子比特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获现实量子比特所经历的噪声动态。本文研究了T1和T2的涨落如何被包含在量子信道模型中。我们提出了随时间变化的量子通道（TVQC）模型的想法，我们展示了它们如何提供一个更真实的写照比静态模型在某些情况下的退相干效应。我们还讨论了TVQC和它们的静态同行之间存在的分歧，通过一个度量称为钻石规范。在许多情况下，这种分歧可能是显着的，这表明必须考虑退相干的时间依赖性，以便构建捕获量子器件的真实的性质的模型。
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 ofT1andT2, 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 ofT1andT2can 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.