Semiconductor Cavity QED

该项目建立在对两个“振荡器”之间的共振近场耦合加速衰减（Purcell）的突破性观察之上——一个是单个半导体量子阱（InGaAs）的典型增益，另一个是具有非常大偶极矩的金属（银）分裂环谐振器阵列的非常强的吸收。这种耦合的观测是可能的，因为分裂环谐振器产生的巨大真空场具有模体积V，比在介电材料（硅或砷化镓）中制造的光子晶体板腔的最小V小一千倍。人们可以从量子阱的结果中预测，人们甚至应该能够看到这样一个谐振器和单个静止量子点之间的耦合——这是这个项目的主要目标——从而为光-物质（谐振器-发射器）相互作用开辟了一个新的领域。通常，珀塞尔增强（与Q/V成正比）是在质量因子Q非常高的介质腔中实现的。因此，增强只发生在位于腔峰非常窄的频率范围内的发射极。与此相反，裂环谐振器的Q值仅为10阶；尽管如此，由于金属谐振器的模体积非常小，珀塞尔增强仍然很大。因此，具有跃迁的发射器位于非常宽的共振范围内的任何地方，受到非常大的真空场，并使其自发发射加速，导致其辐射展宽光谱的重叠。原子和半导体腔QED的基础研究成果对半导体激光技术产生了深远的影响。一个具体的正在进行的例子是垂直腔面发射激光器（VCSEL）的发展，由该小组的毕业生开创。单量子点腔QED使纳米科学超越了传统的非线性光学和激光物理，进入了一个新的动态过程和有源器件，现在涉及到一个接一个的量子点和光子。这项关于单片固态腔中的量子光学的研究将继续在AMO和纳米光子学领域之间建立新的联系，这一联系始于一篇被高度引用的《自然》文章中对强耦合的观察。

This project builds on the breakthrough observation of accelerated decay (Purcell) of the resonant near-field coupling between two "oscillators" -- one the typical gain of a single semiconductor quantum well (InGaAs) and the other the very strong absorption of an array of metallic (silver) split ring resonators with very large dipole moments. The observation of this coupling is possible because of the giant vacuum field produced by the split ring resonator having a mode volume, V, a thousand times smaller than the minimum V for a photonic crystal slab cavity fabricated in a dielectric (silicon or GaAs). One can predict from the quantum well results that one should even be able to see coupling between such a resonator and a single stationary quantum dot -- the principal goal of this project -- thus opening a new regime for light-matter (resonator-emitter) interaction. Usually, Purcell enhancement (proportional to Q/V) is achieved in a dielectric cavity of very high quality factor, Q. Thus, enhancement occurs only for an emitter lying within the very narrow range of frequencies of the cavity peak. In contrast here, the Q of the split ring resonator is only of order 10; nonetheless, the Purcell enhancement is still large because of the metallic resonator's very tiny mode volume. Consequently, emitters with transitions lying anywhere within the very broad resonance are subjected to a very large vacuum field and have their spontaneous emission accelerated, resulting in overlap of their radiatively broadened spectra.The results of fundamental atomic and semiconductor cavity QED research have had lasting impact on semiconductor laser technology. A specific ongoing example is the development of the vertical-cavity surface-emitting laser (VCSEL) pioneered by a graduate from this group. Single quantum dot cavity QED enables nanoscience to go beyond traditional nonlinear optics and laser physics into a new regime with dynamical processes and active devices now involving quantum dots and photons taken one by one. This research on quantum optics in monolithic solid-state cavities would continue to forge new links between the AMO and nanophotonics communities begun by the observation of strong coupling reported in a highly-cited Nature article.