Efficient sources and strong filters for silicon quantum photonics in the mid-infrared

在接近硅(2.1微米)双光子能带边缘的波长，量子信息处理应用受益于许多理想的特性。在这里，硅的双光子吸收速率最小，在非线性折射中最大，这使得该波段成为低损耗非线性硅光子学的理想波段。具体地说，这些特性在利用自发四波混频(SFWM)的光子对源的设计中是需要的。光子对源在计算、通信和传感等领域支撑着许多量子技术，因此发展明亮、高纯度、不可分辨和高预警效率的光子源至关重要。基于SFWM的光源由高强度泵浦激光器供电，随后必须将其与单光子产品分离，并需要精确到单光子级别(-130dB)的抑制。这个项目将从上方解决这个问题--通过提高SFWM源的效率--并从下方--通过改进泵的抑制过滤器来解决。将探索使用光子晶体腔作为光子对源，以产生相对较低泵浦功率的高质量光子。这些信号源设计将结合用于泵浦抑制的高消光比滤光器、集成片上滤光器和黑体背景片上滤波的新想法。这些滤光片本质上既是光谱滤光片又是空间滤光片。这些发展将打开新的应用，依赖于在硅芯片上集成预告的光子对源。

At wavelengths near the two-photon band edge of silicon (2.1um) quantum information processing applications benefit from many desirable properties. Here, silicon exhibits a minimum in the two-photon absorption rate and a maximum in the nonlinear refraction, making this band ideal for low-loss nonlinear silicon photonics. Specifically, these properties are desired in the design of photon pair sources utilising spontaneous four wave mixing (SFWM). Photon pair sources underpin many quantum technologies in computation, communications and sensing and so the development of bright, high purity, indistinguishable and high heralding efficiency photon sources is crucial. SFWM based sources are powered by an intense pump laser which must be subsequently separated from the single photon products, with suppression needed right down to the single photon level (-130dB). This project will attack this problem from above-by making SFWM sources more efficient-and from below-by making pump-rejection filters better. The use of photonic crystal cavities as photon-pair sources will be explored to produce high-quality photons with relatively low pump powers. These source designs will be combined with fresh ideas on high-extinction-ratio filters for pump rejection, integrated on-chip, and with on-chip filtering of blackbody background. These filters will be both spectral and spatial in nature. These developments will open new applications relying on the integration of heralded photon-pair sources on silicon chips.