Waveguide QED: Quantum Optics of Multiple Two-Level-Systems Strongly Coupled to 1D Bosons

光和物质之间的强烈相互作用导致了新的物理现象和新的量子信息处理能力。到目前为止，显示出如此强烈互动的主要系统很难扩展和连接在一起。本文从理论上研究了一种新的、开放的、可扩展的强相互作用系统：一维波导与一个或多个量子系统的相互作用。量子系统使波导中的光子纠缠和关联，产生一种新的多光子束缚态。人们正在研究这些束缚态的许多效应，例如相关的光子阻塞。正在评估它们在量子通信中的使用，特别是在被称为量子密钥分发的密码学任务中的使用。该项目对两个更广泛的领域产生了重大影响。首先，纳米级的光子设备通常包括这样的波导和量子系统作为构建块。这里研究的新的物理效应有助于更好地理解这些元素，并可能带来定性的新器件。其次，新兴的“量子网络”模式涉及的元素看起来与这里提出的波导系统一模一样。培训初级研究员是该项目的关键影响：研究生涉及方方面面，因此完全接受了多体和量子光学理论以及潜在的纳米光子学和量子信息应用方面的培训。最后，协办个人参与当地学校的外展工作。

Strong interaction between light and matter leads both to novel physical phenomena and to new quantum information processing capabilities. The main systems showing such strong interactions to date are difficult to scale and connect together. In this work, a new, open, scalable system with strong interactions is studied theoretically: a one-dimensional waveguide interacting with one or several quantum systems. The quantum systems cause the photons in the waveguide to become entangled and correlated, generating a new kind of multi-photon bound state. The many effects of these bound states are being investigated, such as the associated photon blockade. Their use for quantum communication, and in particular for the cryptography task known as quantum key distribution, are being evaluated. This project substantially impacts two broader fields. First, nanoscale photonic devices often involve such waveguides and quantum systems as building blocks. The new physical effects studied here are leading to a better understanding of such elements and may lead to qualitatively new devices. Second, the emerging paradigm of "quantum networks" involves elements that look exactly like the waveguide systems proposed here. Training a junior researcher is a key impact of this project: a graduate student is involved in all aspects and so is thoroughly trained in many-body and quantum optics theory as well as potential nano-photonics and quantum information applications. Finally, the co-PIs are involved in outreach in the local schools.