Detector tomography on IBM quantum computers and mitigation of an imperfect measurement
Detector tomography on IBM quantum computers and mitigation of an imperfect measurement
复制标题
DOI：
10.1103/physreva.100.052315
复制
发表时间：
2019-11-13
影响因子：
2.9
通讯作者：
Wei, Tzu-Chieh
中科院分区：
文献类型：
--
作者：
Chen, Yanzhu;Farahzad, Maziar;Wei, Tzu-Chieh
我们使用量子探测器层析成像来表征IBM量子计算机上的测量阳性操作员值衡量标准（POVM）IBM Q 5 Tenerife和IBM Q 5 Yorktown上的量子读数。我们的结果表明，特征的检测器模型偏离了理想投影仪，范围为10％至40％。这主要由经典错误主导，从相应的Bloch-vector表示中的极点的箭头收缩可以明显看出。还有一些小的偏差，不是“经典”的阶，以3％或以下的阶段，由Z轴的箭头倾斜表示。可以通过采用两种或更高的检测器模型而不是一个设备中所有量子位的独立单量检测器来进一步改进此特征。我们还找到了指示检测器行为相关的证据，即，当其他量子器及其探测器正在运行时，检测器表征会稍微改变（百分之几）。这种特殊的行为与栅极组层析成像的更复杂方法的表征一致。我们还讨论了表征检测器的POVM，尽管偏离了理想投影仪，但仍可以用来估计理想的检测分布。
We use quantum detector tomography to characterize the qubit readout in terms of measurement positive operator-valued measures (POVMs) on IBM quantum computers IBM Q 5 Tenerife and IBM Q 5 Yorktown. Our results suggest that the characterized detector model deviates from the ideal projectors, ranging from 10 to 40%. This is mostly dominated by classical errors, evident from the shrinkage of arrows from the poles in the corresponding Bloch-vector representations. There are also small deviations that are not "classical," of order 3% or less, represented by the tilt of the arrows from the z axis. Further improvement on this characterization can be made by adopting two- or more-qubit detector models instead of independent single-qubit detectors for all the qubits in one device. We also find evidence indicating correlations in the detector behavior, i.e., the detector characterization is slightly altered (to a few percent) when other qubits and their detectors are in operation. Such peculiar behavior is consistent with characterization from the more sophisticated approach of the gate set tomography. We also discuss how the characterized detectors' POVMs, despite deviation from the ideal projectors, can be used to estimate the ideal detection distribution.