发表机构
University of Geneva; Technische Universität Wien; Atominstitut, Technische Universität Wien; Vienna Center for Quantum Science and Technology (VCQ), Technische Universität Wien; Geneva Quantum Centre, University of Geneva（日内瓦大学; 维也纳工业大学; 维也纳工业大学原子研究所; 维也纳工业大学量子科学与技术维也纳中心; 日内瓦大学量子研究中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出一个基于量子信道理论的通用框架，通过平均信道保真度量化量子存储器性能，并应用于固态实验，认证了98.6%的保真度。
AI 中文摘要
量子存储器是未来量子网络的关键组成部分。因此，开发对其认证的方法是一个重要但具有挑战性的问题。在这项工作中，我们提出了一个用于认证量子存储器并以操作性和高效方式量化其性能的通用框架，利用了量子信道理论的发展。我们首先对这些概念和工具进行教学式介绍，并说明它们在量子存储器中的自然应用。具体来说，我们通过平均信道保真度的概念来量化量子存储器的保真度，该保真度可以通过实验中一组有限的探针态（形成所谓的2-设计）精确估计。然后，我们提出了多种用于认证该量的见证技术，并表明它可以访问信道的其他重要属性，例如其维度和传输量子信息的能力。我们主要考虑简单的制备-测量场景，但也讨论了基于纠缠的设置以及半设备无关方法。最后，我们将这些方法应用于固态量子存储器实验，认证了98.6%的平均信道保真度。我们的认证方法可以很容易地应用于其他量子设备，如光纤、换能器和门。
英文摘要
Quantum memories are key ingredients for future quantum networks. Developing methods for their certification is therefore an important, yet challenging, problem. In this work, we present a general framework for certifying quantum memories and quantifying their performance in an operational and efficient manner, taking advantage of developments in the theory of quantum channels. We start by giving a pedagogical introduction to these concepts and tools and illustrate their natural application to quantum memories. Specifically, we quantify the fidelity of a quantum memory via the notion of average channel fidelity, which can be estimated precisely in an experiment via a finite set of probe states forming a so-called $2$-design. We then present a number of witnessing techniques for certifying this quantity, and show that it gives access to other important properties of the channel, such as its dimensionality and its capacity to transmit quantum information. We consider mostly a simple prepare-and-measure scenario, but discuss also the case of an entanglement-based setup, as well as a semi-device-independent approach. Finally, we apply these methods to a solid-state quantum memory experiment, certifying an average channel fidelity of 98.6%. Our certification methods can be readily applied to other quantum devices, such as fibers, transducers and gates.
Comments12+8 pages ; 6+2 figures
