In October 2019, Nature published a paper [6] describing an experimental work that was performed at Google. The paper claims to demonstrate quantum (computational) supremacy on a 53-qubit quantum computer. Since then we have been involved in a long-term project to study various statistical aspects of the Google experiment. In [30] we studied Google's statistical framework that we found to be very sound and offered some technical improvements. This document describes three main concerns (based on statistical analysis) about the Google 2019 experiment. The first concern is that the data do not agree with Google's noise model (or any other specific model). The second concern is that a crucial simple formula for a priori estimation of the fidelity seems to involve an unexpected independence assumption, and yet it gives very accurate predictions. The third concern is about statistical properties of the calibration process.

翻译：2019年10月，《自然》杂志发表了一篇论文[6]，描述了谷歌进行的一项实验性工作。该论文声称在53量子比特量子计算机上实现了量子（计算）霸权。自那时起，我们一直参与一个长期项目，研究谷歌实验的各个统计方面。在[30]中，我们研究了谷歌的统计框架，发现其理论基础非常扎实，并提出了一些技术改进。本文阐述了（基于统计分析）对谷歌2019年实验的三个主要关切点。第一点关切是实验数据与谷歌的噪声模型（或任何其他特定模型）不符。第二点关切是，一个用于先验估计保真度的关键简化公式似乎包含了一个不合理的独立性假设，但该公式却能给出非常精确的预测。第三点关切是关于校准过程的统计特性。