标题： 量子过程层析误差条的实际性和可靠性 显示英文标题

标题： Practical and reliable error bars for quantum process tomography

摘要： 量子过程层析成像的当前技术通常基于有限但大量的测量数据，返回未知过程的一个单点估计。 然而，由于统计涨落，接近该单点估计的其他过程也可能以接近确定性产生观察到的数据。 除非可以构建适当的误差条，否则该单点估计没有任何可靠的可操作解释。 在这里，我们通过为量子过程构造置信区域估计器来解决此问题。 我们的方法能够可靠地估计几乎任何涉及少量量子比特的量子过程的优值指标，包括与特定噪声模型的钻石距离、纠缠保真度以及最差情况下的纠缠保真度，通过识别高概率包含真实状态的误差区域实现。 我们还提供了一个软件包——QPtomographer——用于实现我们的钻石范数和最差情况纠缠保真度估计器。 我们用几个模拟示例展示了其使用方法和性能。 我们的工具可用于可靠地验证例如纠错码、幺正门的实现或其他一般影响量子系统的噪声过程的性能。 显示英文摘要

摘要： Current techniques in quantum process tomography typically return a single point estimate of an unknown process based on a finite albeit large amount of measurement data. Due to statistical fluctuations, however, other processes close to the point estimate can also produce the observed data with near certainty. Unless appropriate error bars can be constructed, the point estimate does not carry any sound operational interpretation. Here, we provide a solution to this problem by constructing a confidence region estimator for quantum processes. Our method enables reliable estimation of essentially any figure-of-merit for quantum processes on few qubits, including the diamond distance to a specific noise model, the entanglement fidelity, and the worst-case entanglement fidelity, by identifying error regions which contain the true state with high probability. We also provide a software package---QPtomographer---implementing our estimator for the diamond norm and the worst-case entanglement fidelity. We illustrate its usage and performance with several simulated examples. Our tools can be used to reliably certify the performance of e.g. error correction codes, implementations of unitary gates or more generally any noise process affecting a quantum system.