PHOCIS- A Photonic Crystal Integrated Squeezer

近几十年来，物理学家们越来越明白，控制量子系统的能力将在一系列技术上带来强大的增强，使解决大量重要计算问题的最著名的经典算法黯然失色，并克服测量、传感和成像方面的经典限制。在单个光子的水平上，光也受量子力学规则的支配。随着我们产生、控制和测量光的能力的进步，我们也越来越多地理解光作为一个平台的潜力，以便将量子现象用于实际目的。量子光学已经在我们观察遥远的宇宙和解决数学问题方面发挥了优势，即使是最强大的超级计算机也无法做到这一点。这些技术需要一种可以编码量子信息的光源。来自激光等所谓“经典”光源的光，对于许多测量或通信任务来说是次优的，不适合用于量子计算。因此，需要新的非经典光源来打开通往量子技术大奖的大门。在这次联谊会中，我将建立一种名为压缩真空的非经典光源。这种以光子成对出现为特征的光状态，已经被证明在这些现有的量子优势演示中起到了关键作用。相对于早期技术的一个关键改进是，这种光源将直接在一根光纤中制造。这将有助于将阻止其他挤压真空源投入使用的破坏性损失降至最低。该装置将结合光纤光学的一些最新进展：首先，巴斯大学开发的“光子晶体光纤”允许仔细控制产生非经典光所需的关键特性。其次，纤维本身将通过暴露在激光束中进行修改，使其具有反射性。这将允许我们在光纤内部创建一个光陷，极大地增强产生压缩真空的相互作用。在项目的第二阶段，我将把这个光源与控制系统集成在一起，以允许实时、主动地操纵输出光。然后，我将把这些输出传送到新型探测器中，以便能够实时测量光束中的量子关联。通过在这个系统的控制阶段和检测阶段之间实现主动反馈，我的目标是将“基于测量的量子计算”--一个实现量子信息处理全部潜力的实用框架--所需的元素结合在一起。作为一个额外的好处，这项研究将产生比量子计算更广泛的影响，开发的方法适用于新的经典光源和先进的领域，如光谱学和成像。

In recent decades, physicists have increasingly understood that the ability to control quantum systems will unleash powerful enhancements across a range of technologies, eclipsing the best known classical algorithms for a plethora of important computational problems and overcoming classical limits in measurement, sensing and imaging. At the level of individual photons, light is also governed by the rules of quantum mechanics. As our ability to generate, control, and measure light progresses, so grows our understanding of its potential as a platform for harnessing quantum phenomena for practical purposes. Quantum optics has already delivered advantages in our ability to observe the distant universe and solve mathematical problems beyond the reach of even the most powerful supercomputers.These technologies demand a source of light into which quantum information can be encoded. Light from so-called "classical" sources, such as lasers, is suboptimal for many measurement or communication tasks and unsuitable for quantum computing. Therefore, new sources of "nonclassical" light are required to unlock the door to the great prizes of quantum technology.In this fellowship, I will build a source of a type of nonclassical light called "squeezed vacuum". This state of light, characterised by photons appearing in pairs, has already proven pivotal in these existing demonstrations of quantum advantage.A crucial improvement over earlier technology is that this source will be fabricated directly inside a single piece of optical fibre. This will help minimise the destructive losses which prevent other squeezed vacuum sources being put to use. This device will incorporate some of the newest advances in fibre optics: Firstly, "photonic crystal fibre", developed at the University of Bath, allows careful control over critical properties necessary for the generation of nonclassical light. Secondly, the fibre itself will be modified by exposure to a laser beam, making it reflective. This will allow us to create a light-trap inside the fibre, greatly enhancing the interaction that generates squeezed vacuum. In the second phase of the project, I will integrate this source with control systems to allow real-time, active manipulation of the output light. I will then route this output into new types of detector with the ability to measure quantum correlations in the beam in real time. By enabling active feedback between the control and detection stages of this system, I aim to bring together the elements necessary for "measurement-based quantum computing"- a practical framework for realising the full potential of quantum information processing.As a bonus, this research will have a wider impact beyond quantum computing, with the methods developed applicable to new sources of classical light and advancing fields such as spectroscopy and imaging.