Semiconductor Devices for Entangled Light Generation

测量纠缠对中的一个光子会改变另一个光子的量子态，即使它们之间的距离为1000‘S千米。爱因斯坦将这种奇特的特性描述为“远距离的诡异行为”。除了让量子理论的假设得到检验之外，纠缠光子的来源也是量子信息技术应用的重要资源。例如，它们实现了量子隐形传态，这是一种用于在量子通信系统或量子计算机中传输量子信息的协议。尽管纠缠有很多潜在的用途，但目前还没有现成的纠缠光子源。关于纠缠的实验室实验通常依赖于用强大的激光在绝缘晶体中泵浦微弱的、非线性的过程。然而，最近的工作表明，纠缠光子可以由简单的光或电驱动的半导体器件产生。[1，2]该项目将从用微型光致发光光谱表征单个量子点开始。量子点是由液滴外延方法产生的，由于其对称的形状，在纠缠光子源中很有希望使用。该项目将测量激子跃迁能量和偏振分裂，并将其与点的电子结构联系起来。博士将对产生纠缠光子的新型半导体器件进行研究。其目标将是开发对量子信息应用有用的源，即。表现出高纠缠保真度、光子不可分辨和发射效率。这些源将被优化并应用于量子通信中的不同应用，如量子隐形传态、[3，4]纠缠交换和量子中继器。在后一阶段，信号源将在英国量子网络中安装的光纤上实施。这项工作主要是实验性的，尽管可能涉及大量的理论。它将涉及使用电子束和光刻制造半导体器件，以及通过光学光谱学、量子态断层扫描和量子光学中的其他实验来表征这些器件。该项目将使用位于剑桥的东芝研究欧洲有限公司最先进的设施。

Measurement of one of the photons in an entangled pair alters the quantum state of the other, even if they are separated by 1000's of km. Einstein described this peculiar property as 'spooky action at a distance'. As well as allowing the postulates of quantum theory to be tested, sources of entangled photons are an essential resource for applications in quantum information technology. For example, they enable quantum teleportation, the protocol used to transfer quantum information in a quantum communication system or quantum computer. Though entanglement has many potential uses, there is currently no 'off-the-shelf' source of entangled photons. Lab experiments on entanglement often rely on pumping weak, non-linear processes in an insulating crystal with a powerful laser. However, recent work has shown that entangled photons can be produced by simple optically or electrically-driven semiconductor devices.[1,2] The project will begin by characterizing individual quantum dots by micro-photoluminescence spectroscopy. The quantum dots are produced by the droplet epitaxy method, which is promising for use in entangled photon sources, due to their symmetric shape. The project will measure the exciton transition energies and polarisation splittings and relate this to the electronic structure of the dots. The PhD will conduct research on novel semiconductor devices for generating entangled photons. The objective will be to develop sources that are useful for quantum information applications, ie. displaying high entanglement fidelity, photon indistinguishability and emission efficiency. The sources will be optimized and applied to different applications in quantum communications, such as quantum teleportation,[3,4] entanglement swapping and quantum repeaters. In the latter stages the sources will be implemented on installed fibre in the UK Quantum Network. The work is mostly experimental, although could involve a significant amount of theory. It will involve fabrication of semiconductor devices using e-beam and photolithography, as well as the characterisation of these devices by optical spectroscopy, quantum state tomography and other experiments in quantum optics. The project will use state-of-the-art facilities at Toshiba Research Europe Ltd in Cambridge.