FET: Small: Spectrally Efficient High-dimensional Quantum Communications in an Integrated Quantum Photonic Platform

量子信息处理为下一代高精度传感、高性能计算和可靠通信开辟了新的途径。纠缠是量子信息处理的独特资源。量子通信是充分释放纠缠力量的基石。在安全通信方面，量子通信利用量子力学的基本原理来实现具有可验证安全性的密钥分发，称为量子密钥分发(QKD)。尽管量子通信具有吸引人的特点，但在其广泛应用之前，需要解决一些根本和技术挑战。该项目将开发高维协议和量身定制的高效光子集成电路，以大幅推进可扩展、高速率和长距离的量子通信，从而为实际部署中面临的挑战提供解决方案。这项工作使高频谱效率的量子通信成为可能，从而大大提高了通信速率。因此，该项目将代表着朝着可大规模生产的低成本集成量子通信系统迈出的关键一步。高维量子通信使量子信息能够在大的希尔伯特空间中传输，为构造新的量子纠错码、构建高效的量子中继器和高速率量子保密通信开辟了前景广阔的道路。该项目旨在引入一种新的量子通信框架，将高维纠缠量子比特编码在正交的Slepian序列基中。该方法对自由空间光链路中的湍流效应和光纤信道中的色散效应/非线性具有很强的鲁棒性，从而提高了量子通信距离。Slepian态的产生、处理和检测将在一个集成的量子光子学平台中实现。该项目将使在非线性光子集成电路中实现的电控波导布拉格光栅(EC-WBG)的开发成为可能，它是用于高维量子通信的量子发射器和接收器的关键部件。与光纤Bragg光栅相比，EC-WBG可以在光子集成电路平台上批量制造，从而可以处理以大量相互无偏的基来编码的量子信息。这样，可伸缩性显著提高，同时大大降低了成本。Slepian态源和基于光子集成电路的EC-WBG将被集成在一起，以执行包括高维纠缠分布和高维QKD在内的量子通信任务。该项目致力于1)分析基于Slepian态的高维量子通信协议；2)在光子集成电路平台上开发纠缠和单光子级别的Slepian态源和可扩展的处理单元；3)演示Slepian态高维量子通信系统，并在真实世界量子网络试验台上测试开发的高维量子通信原型。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Quantum information processing opens new avenues for next-generation high-precision sensing, high-performance computing, and reliable communications. Entanglement is a unique resource for quantum information processing. Quantum communication is the cornerstone to fully unleash the power of entanglement. On the secure communication front, quantum communication leverages underlying principles of quantum mechanics to realize distribution of keys with verifiable security, known as Quantum Key distribution (QKD). Despite appealing features of quantum communication, a number of fundamental and technical challenges need to be tackled prior to its widespread applications. This project will develop high-dimensional protocols and tailored efficient photonic-integrated circuits to substantially advance scalable, high-rate, and long-haul quantum communications, thus providing solutions to challenges faced in practical deployments. This work enables high spectral efficiency quantum communications so that communication rates can be substantially improved. As such, this project will represent an essential step toward low-cost integrated quantum communication systems that can be mass-produced.High-dimensional quantum communication enables transmitting quantum information in a large Hilbert space, opening promising routes for constructing new quantum error-correcting codes, building efficient quantum repeaters, and high-rate quantum-secured communications. The project seeks to introduce a new framework of quantum communications with high-dimensional entangled-qubits encoded in orthogonal Slepian sequences bases. This approach is highly robust against turbulence effects in free-space optical links and dispersion effects/nonlinearities in fiber-optics channels, thereby improving the quantum communication distance. Generation, processing, and detection of Slepian-states will be implemented in an integrated quantum photonics platform. This project will make possible the development of electronically controlled waveguide Bragg gratings (EC-WBGs) implemented in nonlinear photonic-integrated circuits as a key component employed in the quantum transmitters and receivers for high-dimensional quantum communications. Compared to fiber Bragg gratings, EC-WBGs can be mass fabricated in a photonic-integrated circuit platform, so that quantum information encoded in a large number of mutually unbiased basis can be processed. As such, scalability is significantly improved while substantially reducing the cost. The Slepian-state sources and the photonic-integrated circuits-based EC-WBGs will be integrated to perform quantum communication tasks including high-dimensional entanglement distribution and high-dimensional QKD. This project is dedicated to 1) analyzing high-dimensional quantum communication protocols based on Slepian states; 2) developing entangled and single-photon-level Slepian-state sources and scalable processing units in a photonic-integrated circuit platform; and 3) demonstrating Slepian-state high-dimensional quantum communication systems and testing the developed high-dimensional quantum communication prototypes in a real-world quantum network testbed.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.