ECCS/EPMD: Single-photon quantum information processing with nonlinear photonic integrated circuits

光子之间的量子关联和纠缠的创建和控制对于量子信息处理至关重要，特别是对于量子网络协议，包括双光子量子逻辑和有效的纠缠交换，这需要光子-光子相互作用。强光子-光子相互作用通常通过高度非线性系统实现，例如由原子与高q光学腔耦合组成的腔-量子电动力学（QED）系统，或通过基于测量的后选择方法。尽管有成功的演示，但这些方法涉及复杂的设置和/或严格的实验条件，对于更复杂和更大规模的量子信息任务来说，可以说是困难的。因此，实现基于体光学非线性而不依赖量子发射体的光子-光子相互作用是非常可取的。然而，由于弱块体光学非线性，量子光子系统，包括块体晶体和集成光子电路，几乎完全在参数状态下运行，用于诸如预示的单光子源和连续变量量子信息任务（基于测量的协议通常是概率的除外）。在块状材料中实现单光子非线性和大量光子-光子相关仍然是一个突出的挑战，这对量子信息应用是有用的。在这个项目中，我们将使用一种结合最先进的集成量子光子平台和创新量子光学方法的方法来解决这一基本挑战，这将导致关键的量子光学协议，包括光子的量子非破坏测量-一种可能彻底改变所有光学量子信息处理的能力。我们将利用我们最近开发的具有创纪录高光学非线性的集成量子光子平台，实现少光子量子相干全光。我们的方法基于波导耦合非线性光学腔的量子干涉，通过控制其线性响应，可以在集成光子系统中产生和操纵少光子量子相关。这将使我们能够演示几个关键的量子光学协议，包括光子的量子非拆除测量和高保真度的同步纠缠交换。该项目的成果将在利用量子相干性、增强光子量子信息处理以及为实现中继器量子网络铺平道路方面产生更广泛的影响。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。

Creation and control of quantum correlations and entanglement between photons is critical to quantum information processing and particularly for quantum network protocols, including two-photon quantum logic and efficient entanglement swapping, which requires photon-photon interaction. Strong photon-photon interaction is typically achieved via highly nonlinear systems, such as cavity-quantum electrodynamics (QED) systems consisting of atoms coupled with high-Q optical cavities, or by measurement-based, post-selection methods. Despite successful demonstrations, these approaches involving complicated setups and/or stringent experimental conditions are arguably difficult for more complex and upscaled quantum information tasks. It is thus highly desirable to realize photon-photon interaction based on bulk optical nonlinearities without resorting to quantum emitters. However, because of the weak bulk optical nonlinearity, quantum photonic systems, including both bulk crystals and integrated photonic circuits, are almost exclusively operated in the parametric regime for applications such as heralded single-photon sources and continuous-variable quantum information tasks (except for measurement-based protocols which are typically probabilistic). It remains an outstanding challenge to realize single-photon nonlinearity with bulk materials and substantial photon-photon correlations that are useful for quantum information applications. In this program, we will tackle this fundamental challenge using an approach combining a state-of-the-art integrated quantum photonic platform and innovative quantum optical methods that will lead to critical quantum optical protocols, including quantum non-demolition measurement of photons—a capability that could revolutionize all of optical quantum information processing. We will realize few-photon quantum coherence all-optically, capitalizing on our recently developed integrated quantum photonic platform with a record-high optical nonlinearity. Our approach, based on quantum interference via waveguide-coupled nonlinear optical cavities, will enable generation and manipulation of few-photon quantum correlations in the integrated photonic system by controlling its linear response. This will allow us to demonstrate several critical quantum optical protocols including quantum non-demolition measurement of photons and synchronous entanglement swapping with high fidelity. The outcome of this program will have broader impacts in harnessing quantum coherence, enhancing photonic quantum information processing, and paving the way towards repeater-enabled quantum networks.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.