Heralded Entangled Sources for All-optical Quantum Networks with a Quantum Advantage

如今，纠缠关联是量子2.0革命的核心，有可能对通信、传感和计算领域产生重大影响。特别是，纠缠态从根本上保证了量子通信的安全，或者说“不可破解”。量子系统对损失和错误极其敏感，构建一个能够有效分配量子纠缠的量子网络是一个未解决的主要挑战，这对量子2.0应用非常有用。现有的量子网络方法都面临着主要的技术障碍，使它们不适合量子通信。该项目将展示一种基于纠缠单光子的新型量子网络。该网络方案基于现有的技术，并且构建它所需的工具今天都是可用的。该网络将用于将纠缠光子分发给两个不同网络节点上的独立用户。即使光子在网络中会经历大量的损耗，分布式纠缠也会受到可忽略不计的误差的影响，以高效率测量，并以高比特率分布——这些都是安全量子通信的必要标准。该网络是可扩展的，这意味着可以添加更多的网络节点，以允许多个用户同时进行安全通信。拟议中的系统对隐私和国家安全具有重要影响。本项目将支持培养两名实验单光子源设计与测量、量子信息与通信理论方面的研究生。该网络可以用作先进的量子网络测试平台，既可以用作教育和培训工具，它将通过一个针对传统上代表性不足的群体的新暑期项目招募的高中和本科实习生来扩展和维护。以可扩展的方式在有损信道上分配高质量的纠缠是一个尚未解决的问题。该项目的目标是开发以MHz速率工作的路径纠缠单光子的相同源，并演示由2公里公共光纤网络分隔的两个源之间的纠缠交换。由此产生的分布式纠缠可用于执行具有可证明的量子优势的高级量子通信协议。一个研究光纤网络连接了NIST和CU博尔德校区，这将用于在两个校区之间以kHz速率分配99%保真度的纠缠态。这种方法是可扩展的，量子2.0已经准备好了，并且将首次展示可证明的量子通信优势，跨越有损的公里级网络链路，其速率比当前最先进的网络演示高5个数量级。这将为中小型多节点量子网络奠定基础，这些网络可以在未来五年内建成，能够分布更大类别的纠缠态。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Today, entangled correlations are at the heart of the Quantum 2.0 revolution with the potential to significantly impact the fields of communications, sensing, and computing. In particular, entangled states power fundamentally secure—or “unhackable”—quantum communication. Quantum systems are extremely sensitive to loss and errors, and it is a major unsolved challenge to build a quantum network that can efficiently distribute entanglement that is useful for Quantum 2.0 applications. Existing approaches to quantum networking all face major technological barriers that make them unsuitable for quantum communication. This project will demonstrate a new type of quantum network based on entangled single photons. The networking scheme is based on existing technology, and the tools required to build it are available today. The network will be used to distribute entangled photons to separate users at two different network nodes. Even though the photons will experience high amounts of loss over the network, the distributed entanglement will be subject to negligible error, measured with high efficiency, and distributed at high bit rates—all necessary criteria for secure quantum communications. The network is scalable, meaning more network nodes can be added to allow secure communication between multiple users simultaneously. The proposed system has important implications for privacy and national security. This program will support the training of two graduate students in experimental single photon source design and measurement, and in quantum information and communications theory. The network can be used as an advanced quantum networking testbed that can be used as both an education and training tool, and it will be expanded and maintained in part by high school and undergraduate interns recruited via a new summer program targeted towards traditionally underrepresented groups.Distributing high-quality entanglement over lossy channels in a scalable manner is an unsolved problem. The goals of this project are to develop identical sources of path-entangled single photons operating at MHz rates, and to demonstrate entanglement swapping between two sources separated by a 2 km public fiber network. The resulting distributed entanglement can be used to carry out advanced quantum communications protocols that have a provable quantum advantage. A research fiber network connects the NIST and CU Boulder campuses, and this will be used to distribute 99% fidelity entangled states between the two campuses at kHz rates. This approach is scalable, Quantum 2.0 ready, and will for the first time demonstrate a provable quantum communications advantage across lossy, kilometer-scale network links at rates five orders of magnitude higher than current state-of-the-art networking demonstrations. This will lay the groundwork for small-to-medium sized multi-node quantum networks that can be built within the next five years that are capable of distributing larger classes of entangled states.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.