The recently established resource theory of quantum coherence allows for a quantitative understanding of the superposition principle, with applications reaching from quantum computing to quantum biology. While different quantifiers of coherence have been proposed in the literature, their efficient estimation in today’s experiments remains a challenge. Here, we introduce a collective measurement scheme for estimating the amount of coherence in quantum states, which requires entangled measurements on two copies of the state. As we show by numerical simulations, our scheme outperforms other estimation methods based on tomography or adaptive measurements, leading to a higher precision in a large parameter range for estimating established coherence quantifiers of qubit and qutrit states. We show that our method is accessible with today’s technology by implementing it experimentally with photons, finding a good agreement between experiment and theory.

最近建立的量子相干资源理论允许对叠加原理进行定量理解，其应用范围从量子计算到量子生物学。尽管在文献中已经提出了不同的连贯性量词，但是在当今的实验中如何有效地估计它们仍然是一个挑战。在这里，我们介绍了一种集体测量方案，用于估计量子态的相干量，这需要对状态的两个副本进行纠缠测量。正如我们通过数值模拟显示的那样，我们的方案优于基于层析成像或自适应测量的其他估计方法，从而在较大的参数范围内可以更高的精度来估计已建立的qubit和qutrit状态相干量词。