QII-TAQS: All-Photonic Quantum Network

量子计算机和网络的发展将需要许多粒子之间在量子水平上的大规模连接。这些粒子之间的特殊连接，被称为量子比特纠缠，对于量子计算、通信和传感的应用至关重要。产生这种纠缠的方法已经被深入研究，利用中性原子、离子或超导电路，并依赖于强量子位-量子位相互作用。由于与环境的有害相互作用，这些基于物质的量子比特的成功纠缠是具有挑战性的。本文探索了一种利用基于氮化硅的光子芯片平台实现高纠缠光子态的替代方法。与硅等其他光子芯片材料相比，这种平台具有显著的优势，因为它在集成平台中提供了创纪录的低损耗。实现光子态确定性生成的全光子平台将对所有量子信息技术产生广泛影响。例如，这样的方案将启用基于测量的通用计算，其中计算通过在高度纠缠的资源状态上执行单量子位测量来进行。该研究项目旨在创建一个集成光子学平台，该平台可以以近乎确定的方式以高速率和高保真度产生高度纠缠态的光。这些高度纠缠态将作为可扩展的光子构建块，用于生成量子计算机和量子网络的群集态。该平台将基于频域的非线性多路复用方案，可以克服与空间和时间多路复用相关的低比例损失。利用大规模并行光子片上设备的最新进展，纠缠光子产生的速率将显著提高，该设备可以(1)在定义良好的光谱网格内高效地产生和转换光子，(2)使用大规模并行微米尺寸的设备，在数百纳秒的时间尺度上高效地按需存储光。据预测，纠缠贝尔对的产生速率可以在目前的基础上增加至少两个数量级，从1微秒增加到200微秒。最终，这项工作的目标是建立一个可扩展的平台，在这个平台上，纠缠光子的生成速率仅随资源（探测器、谐振器等）的数量呈多项式（而不是指数）增长。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。

Development of quantum computers and networks will require large-scale connections at the quantum level between many particles. These special connections between the particles, known as qubit entanglement, are essential for applications in quantum computing, communications, and sensing. Approaches that have been intensely studied to generate such entanglement utilize neutral atoms, ions, or superconducting circuits and rely on strong qubit-qubit interactions. Successful entanglement of these matter-based qubits is challenging due to deleterious interactions with the environment. Here an alternative approach is explored using a photonic-chip platform based on silicon nitride to realize highly entangled photon states. Such a platform has significant advantages over other photonic-chip materials such as silicon by offering record low losses in an integrated platform. Realization of an all-photonic platform for deterministic generation of photonic states will have broad impact across all quantum information technologies. For example, such a scheme would enable measurement-based universal computation, where computation occurs by performing single-qubit measurements on a highly-entangled resource state.This research project aims to create an integrated photonics platform that can generate highly-entangled states of light in near-deterministic fashion at high rates and with high fidelity. These highly-entangled states will serve as scalable photonic building blocks for generating cluster states for quantum computers and quantum networks. The platform will be based on a nonlinear multiplexing scheme in the frequency domain that allows overcoming the poor scaling with loss associated with spatial and temporal multiplexing. The rate of entangled photon generation will be dramatically increased by leveraging recent advances in massively parallel photonic on-chip devices that can (1) generate and convert photons within a well-defined spectral grid with high efficiency and (2) store light on-demand for timescales on the order of hundreds of nanoseconds with high efficiency, using massively parallel micron-size devices. It is projected that the generation rate of entangled Bell pairs can be increased over what is currently possible by at least two orders of magnitude, from 1 microsecond to 200 microseconds. Ultimately, the work aims to lead to a scalable platform for which the generation rate of entangled photons scales only polynomially (as opposed to exponentially) with the number of resources (detectors, resonators, etc.).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.