All-Fiber Quantum Optics with Colloidal Nanosemiconductors

光纤现在通常被称为传输光的互联网主干，而纳米材料是一种定制物质属性以产生创新应用的工具；这项提议是两种技术的结合，旨在实现直接在光纤内按需产生光子以进行信息编码的长期目标。由这种发射和引导光量子(即光子)的光纤组成的网络，将是迈向量子互联网的一步，量子互联网将从牢不可破的密码学发展到保护在线机密信息。在这种背景下，经济学家预测，到2030年，加拿大的量子技术产业将达到82亿美元，雇用1.6万名加拿大人。目前的单光子源都在光纤之外，面临着光耦合和便携性的挑战。此外，它们的体系结构和大多数制造方法都不是那么简单和可扩展的。这些问题将通过光纤中的发光纳米晶源得到解决，这种光源可以很容易地拼接在一起。然而，胶体合成半导体纳米晶体，即量子点，还没有提供可靠的量子技术体系。因此，我们将一举两得，将量子点嵌入保护性的透明塑料中，加热并拉入光纤。事实上，光发射速率也将加快，并与其他引入不可靠波动的机制的熄灭竞争。首先，我们将演示如何利用不同的光纤设计来控制这种自发辐射率，这要归功于珀塞尔效应。为了验证这种效果，嵌入的量子点系综的光致发光衰减轨迹将被记录在光纤输出端。当拉出光纤，然后将它们切割成单光子源时，量子点的浓度将是隔离它们的关键参数，这将从它们的反聚束统计数据中得到证实。其次，在这些光源的末端将增加镜面状界面，以增加光与物质的耦合，进一步加速光发射。就像在激光器中发现的那样，制造这些共振光学腔的不同策略将在产生单独的和不可区分的光子方面进行比较。然后，腔模式或量子点能级将被调谐到彼此共振。在调谐过程中，能级和模式的光谱反干扰将确认强耦合。第三，展望未来，我们将探索在聚合物光纤中加入圆形量子环和纳米钻石(包括氮空位中心)的新方法，以编码更多关于单光子的信息或实现更稳健的自旋态编码。最后，在短期内，具有成本效益的纳米晶体合成和光纤制造推动了创新传感应用的发展：为当地技术转让和学生主导的创业创造了有利的环境。

Optical fibers are now commonly known as the Internet backbone transmitting light, whereas nanomaterials are a tool for customizing matter properties to generate innovative applications; this proposal is a meeting of both technologies towards the long term objective of generating photons on demand for information encoding, directly within optical fibers. A network of such fibers emitting and guiding light quanta, i.e. the photons, would be a step towards a quantum internet progressing from unbreakable cryptography to protect confidential information online. In this context, economists forecast an $8.2 billion quantum technology industry, employing 16 000 Canadians, by 2030. Current sources of single photons are all outside optical fibers, facing light coupling and portability challenges. Moreover, their architecture and most fabrication approaches are not so simple and scalable. These issues will be resolved with luminescent nanocrystal sources in optical fiber that can be easily spliced together. However, colloidal synthesis of semiconductor nanocrystals, namely quantum dots, has yet to deliver reliable quantum technological systems. Therefore, we will kill two birds with one stone by embedding the quantum dots in protective transparent plastic to be heated and drawn into an optical fiber. Indeed, the light emission rate will also accelerate and compete with the quenching of other mechanisms introducing unreliable fluctuations. Firstly, we will demonstrate control of this spontaneous emission rate with different optical fiber designs thanks to the Purcell effect. To verify the effect, photoluminescence decay traces of embedded quantum dot ensembles will be recorded at the fiber output. The concentration of quantum dots will be a key parameter to isolate them apart when drawing the optical fiber, then cutting them out into single photon sources as will be confirmed by their antibunching statistics. Secondly, mirror-like interfaces will be added at the ends of these sources to increase the light-matter coupling and accelerate the light emission even further. Different strategies to fabricate these resonating optical cavities, as found in lasers, will be compared in terms of generating individual and indistinguishable photons. Then, either the cavity modes or the quantum dot energy levels will be tuned into resonance with one another. A spectral anticrossing of levels and modes during tuning would then confirm a strong coupling. Thirdly, looking ahead towards encoding more information on a single photon or achieving more robust encoding on spin states, we will explore new methods to incorporate circular quantum rings and nanodiamonds, comprising nitrogen vacancy centers, in the polymer optical fibers. Finally in the shorter term, the cost-effective nanocrystal synthesis and fiber fabrication motivate the development of innovative sensing applications: an auspicious environment for local technology transfer and student-led entrepreneurship.