Developing nanophotonics for quantum coherence and control

近十年来，光在信息传输和处理方面取得了很大的进展，基本元件的尺寸越来越小。这一进步是由减少能源需求、提高速度和灵活性以及提高商业和工业应用的整体性能的强烈愿望推动的。目前的研究主要集中在纳米尺度上，纳米光子学这一新兴领域有望实现高带宽、高速度和超小型光电元件。虽然对光学元件小型化的研究经历了实质性的发展，但近年来，在广泛的实验设置中控制和操纵简单量子系统的能力也已经实现。能够利用量子力学效应的受控设备将对量子信息处理（QIP）背景下的通信，计算和传感行业产生重大影响。在这里，量子密码学、量子计算和量子计量等应用与非量子应用相比，在许多任务中提供了卓越得多的性能。我的研究计划的中心目标是研究基于纳米光子学提供的潜力的新一代量子控制设备的可能性。片上纳米制造系统由于组件高密度集成和大规模并行化的可能性，在QIP应用中具有可扩展性的前景。为了利用纳米光子学的潜力来实现高效的量子控制设备，必须首先在理论和实验层面解决许多问题。一个主要问题是两个单光量子的相互作用非常弱。如果在单光子水平上实现强非线性相互作用，将为量子信息的高效相干光学处理开辟可能性。虽然已经提出了各种方案来实现适当的非线性率，但实际问题使它们很难在实验上实现，目前还没有明确的最佳策略。我计划研究用片上光子纳米结构在量子水平上实现大非线性的可能性。为此，我将利用最近发现的表面等离子激元极化子的深亚波长场约束。我打算开发方案来产生非线性量子效应，并利用量子光学工具充分表征它们的性能。到目前为止，还没有在这个新的、令人兴奋的研究方向上进行过研究。主要目标是在量子水平上识别有效的等离子体非线性光学效应，以便在量子相干和控制应用中部署。在纳米光子芯片系统中实现量子控制器件的过程中，还面临着其他主要问题；量子相干性的丧失，非理想的产生和探测，以及可寻址性问题。这些问题意味着，在不久的将来，在任何给定的实验装置中，只有具有强量子特征的小型片上系统和只有弱量子特征的大型片上系统才能有效地生成和控制。我的目标是充分利用新发现的基于QIP的测量技术的潜力来解决这些基本问题。到目前为止，结合基于测量的量子ip和纳米光子片上技术这两个有前途的领域的工作还很少。我将研究这一重要的组合，以便为制造全尺寸相干片上QIP创造一条现实的途径。我将与理论家和实验家合作，以实现这个研究计划的主要目标。

In the past decade, great progress has been made in the transfer and processing of information using light, with the size of basic components becoming progressively smaller and smaller. This advancement has been driven by a strong desire to reduce energy requirements, increase speed and flexibility, and enhance overall performance in commercial and industrial applications. Current research is now firmly based at the nanoscale, where the newly emerging field of nanophotonics promises high bandwidth, high speed and ultra-small optoelectronic components. While research into the miniaturisation of optical components has experienced substantial development, in recent years the capability of controlling and manipulating simple quantum systems in a wide-range of experimental setups has also been achieved. Controlled devices which are able to exploit quantum mechanical effects will have a big impact on the communications, computing and sensing industries in the context of quantum information processing (QIP). Here, applications such as quantum cryptography, quantum computing and quantum metrology offer far superior performance compared to their non-quantum counterparts for a multitude of tasks.The central aim of my research programme is to investigate the possibilities for a new generation of quantum-controlled devices based on the potential offered by nanophotonics. On-chip nanofabricated systems hold the promise of scalability for QIP applications due to the possibility of high-density integration of components and massive parallelisation. In order to harness this potential of nanophotonics for realising efficient quantum-controlled devices, many issues must first be addressed, both at a theoretical and experimental level. One major problem is the very weak interaction of two single light quanta. If strong nonlinear interactions are made possible at the single-photon level, it will open up the possibility for highly efficient coherent optical processing of quantum information. While various schemes have been proposed to achieve the appropriate rates of nonlinearity, practical issues make them extremely hard to realise experimentally and no clear optimal strategy is known at present. I plan to investigate the possibility of achieving large nonlinearities at the quantum level with on-chip photonic nanostructures. To do this, I will exploit the recently discovered deep sub-wavelength field confinement of surface plasmon polaritons. I intend to develop schemes to generate nonlinear quantum effects and fully characterise their performance using quantum optics tools. Up to now, there have been no studies performed in this new and exciting research direction. The main goal is to identify efficient plasmonic nonlinear optical effects at the quantum level for deployment in applications of quantum coherence and control. There are also other major problems faced in the quest for realising quantum-controlled devices in nanophotonic on-chip systems; the loss of quantum coherence, non-ideal generation and detection, and addressability issues. These problems imply that in the near-future, only small sized on-chip systems with strong quantum features and perhaps larger ones characterised by only weak quantum features will be efficiently generated and controlled in any given experimental setup. I aim to take full advantage of the potential of newly discovered measurement-based techniques for QIP to address these fundamental problems. So far, very little work has been performed in combining the two promising areas of measurement-based QIP and nanophotonic on-chip technology. I will investigate this important combination in order to create a realistic route toward the manufacture of full-scale coherent on-chip QIP. I will collaborate with both theorists and experimentalists in order to achieve the major objectives of this research programme.