Reithmaier J P, Sek G, Löffler A, Hofmann C, Kuhn S, Reitzenstein S, Keldysh L V, Kulakovskii V D, Reinecke T L, Forchel A
Technische Physik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Nature. 2004 Nov 11;432(7014):197-200. doi: 10.1038/nature02969.
Cavity quantum electrodynamics, a central research field in optics and solid-state physics, addresses properties of atom-like emitters in cavities and can be divided into a weak and a strong coupling regime. For weak coupling, the spontaneous emission can be enhanced or reduced compared with its vacuum level by tuning discrete cavity modes in and out of resonance with the emitter. However, the most striking change of emission properties occurs when the conditions for strong coupling are fulfilled. In this case there is a change from the usual irreversible spontaneous emission to a reversible exchange of energy between the emitter and the cavity mode. This coherent coupling may provide a basis for future applications in quantum information processing or schemes for coherent control. Until now, strong coupling of individual two-level systems has been observed only for atoms in large cavities. Here we report the observation of strong coupling of a single two-level solid-state system with a photon, as realized by a single quantum dot in a semiconductor microcavity. The strong coupling is manifest in photoluminescence data that display anti-crossings between the quantum dot exciton and cavity-mode dispersion relations, characterized by a vacuum Rabi splitting of about 140 microeV.
腔量子电动力学是光学和固态物理学中的一个核心研究领域，研究腔中类原子发射体的特性，可分为弱耦合和强耦合 regime。对于弱耦合，通过调节离散腔模与发射体的共振与否，自发发射相对于其真空水平可以增强或减弱。然而，当满足强耦合条件时，发射特性会发生最显著的变化。在这种情况下，会从通常的不可逆自发发射转变为发射体与腔模之间的可逆能量交换。这种相干耦合可能为量子信息处理或相干控制方案的未来应用提供基础。到目前为止，仅在大腔中的原子中观察到单个二能级系统的强耦合。在此，我们报告了单个二能级固态系统与光子的强耦合的观察结果，这是通过半导体微腔中的单个量子点实现的。强耦合在光致发光数据中表现为量子点激子与腔模色散关系之间的反交叉，其特征是真空拉比分裂约为 140 微电子伏特。
