Realising scaleable systems for quantum photonics

系统级分析对于实现可扩展量子光子系统至关重要。在开发了许多不完美的低级组件之后，为了实现有用的系统，需要对许多参数进行权衡。前馈是一个有用的研究案例。当前集成光子量子计算体系结构的多个领域都需要测量结果的主动前馈。在基础层面上，前馈是实现通用计算所需的自适应测量所必需的。不确定的单光子源和对光子源以及概率纠缠门意味着需要多路复用方案。这些多路复用方案都需要前馈的前兆光子的测量结果。尽管这一子过程很重要，但它尚未在量子光子学芯片上实现。中红外硅光子学的最新发展为实现前馈提供了机会，因为硅在该波长的高非线性折射率为所需的快速调制器提供了一条途径。该项目将采用系统工程方法来实现中红外的片上前馈，并将开发和整合一些现有和拟议的子系统。这将包括集成的单光子探测器，制导和非制导芯片滤波和中红外调制器。一个关键的问题将是确保所有子系统和器件封装的低温兼容性。该项目将致力于实现一个多路复用源和一个预示纠缠门来执行一层纠缠态融合。根据进展情况，还可以探索无法通过后选择获得的图形状态。

Systems level analysis will be crucial in realising scaleable quantum photonic systems. Having developed many imperfect lower level components, assessing trade-offs over a number of parameters will be required in order to implement useful systems. A useful case study of this is feedforward. Active feedforward of measurement outcomes is required in multiple areas of current integrated photonic quantum computing architectures. At the fundamental level feedforward is necessary to perform the adaptive measurements required to achieve universal computation. Non-deterministic single and pair photon sources, as well as probabilistic entangling gates mean multiplexing schemes will be required. These multiplexing schemes all require the feedforward of the measurement outcome of a heralding photon. Despite the importance of this sub-process, it has not yet been implemented on chip for quantum photonics. Recent developments in mid-infrared silicon photonics provide an opportunity for implementing feedforward, as silicon's high non-linear refractive index at this wavelength provides one route to the fast modulators required. This project will take a system engineering approach to implementing on chip feedforward in the mid-infrared and will look to develop and bring together a number existing and proposed subsystems. This will include integrated single photon detectors, guided and unguided on chip filtering and midinfrared modulators. A crucial problem will be to ensure the cryogenic compatibility of all subsystems and device packaging. The project will aim to implement a multiplexed source and a heralded entangling gate to perform one layer of entangled state fusion. Depending on progress, there may also be scope to explore graph states which are not available through post-selection.