Control of non-classical light states by linear and non-linear interaction in hybrid systems of single semiconductor quantum dots and alkali atomic vapor

该研究项目的中心目标是实现和详细研究新的混合概念和方案，这些概念和方案提供控制，通过单个半导体量子点(QD)发射的光子与作为控制介质的碱性原子蒸汽之间的不同相互作用来产生和/或操纵非经典光态。所有计划研究的基本基础是从单个铟-镓-砷(InGaAs)-量子点产生光谱窄带共振荧光(RF)，作为光子源，可以与~894 nm的铯(133Cs)原子的光学共振(D1超精细结构四重态)进行受控相互作用。复杂的量子点-原子相互作用实验的一个重要前提是RF相对于D1超精细结构的固定原子参考频率的精确调谐能力。(非线性)相互作用的效率将关键取决于光子源之间的相互光谱相似性和热原子气体的光谱响应特性，该光谱响应特性由作为控制介质的多普勒展宽所主导。因此，另一个非常重要的方面是获得对射频发射线宽度的灵活控制，以便根据原子跃迁调整其带宽。在这个项目中，我们计划使用不同的条件技术，即：(A)确定的pi脉冲光学量子点激发，(B)在弱激发区(Heitler区)下，通过在单个量子点上的相干弹性光子散射直接产生超窄带亚泊松射频，以及(C)从pi脉冲和饱和以上的CW修饰发射区域对单量子点射频进行光谱后滤波。这可以通过使用专门设计的高精细度法布里-佩罗涉仪来实现，或者第一次与QD-RF相结合，采用FADOF型(法拉第反常色散光学滤光器)传输滤波技术。利用这种有条件的光子，该项目的预期目标集中在光学量子信息处理领域的基础应用上。我们的目标应用之一将是通过在选定的Cs-D1共振和通过非共振拉曼方案的存储之间的强色散频率区域产生慢光来控制单光子存储和延迟。该项目的第二个主要目标是利用铯原子蒸气与具有可控吸引或排斥原子相互作用的高激发里德堡气体介质相结合来操纵存储的光子和产生更高阶光子数(Fock)态。里德堡气体可以例如充当两个单独的光子合并到共模通道中的光学晶体管。光子-光子散射效应可以通过适当的里德堡泵浦激光对原子介质进行外部控制。

The central aim of the proposed research project is the realization and detailed investigation of new hybrid concepts and schemes which provide control to generate and/or manipulate non-classical states of light by distinct interaction between photons emitted from single semiconductor-quantum dots (QDs) and alkali atomic vapor as the control medium. The fundamental basis for all planned investigations is the generation of spectrally narrow-band resonance fluorescence (RF) from individual single Indium-Gallium-Arsenide (InGaAs)-QDs as a source of photons which can be brought to controlled interaction with the optical resonances of atomic cesium (133Cs) at ~894 nm (D1 hyperfine structure quadruplet). One important prerequisite for sophisticated QD-atom interaction experiments will be a precise tuning capability of RF with respect to the fixed atomic reference frequencies of the D1 hyperfine structure. The efficiency of (non-)linear interactions will critically depend on the mutual spectral similarity between the photon source and the spectral response characteristics of the thermal atomic gas, dominated by Doppler broadening, which acts as the control medium. Therefore, another very important aspect will be to gain flexible control on the RF emission linewidth in order to adjust its bandwidth to the atomic transitions. In this project, we plan to utilize different conditioning techniques, i.e. (a) deterministic pi-pulsed optical QD excitation, (b) direct generation of ultra-narrowband sub-Poissonian RF by coherent, elastic photon scattering on a single QD in the weak excitation regime (Heitler regime), and (c) spectral post-filtering of single-QD RF from the regimes of pi-pulsed and also cw-dressed emission above saturation. This can be achieved by using a specially designed high-finesse Fabry-Pérot interferometer, or alternatively, for the first time in combination with QD-RF, the technique of FADOF-type (Faraday anomalous dispersion optical filter) transmission filtering. Using such conditioned photons, the anticipated goals of the project focus on fundamental applications in the field of optical quantum information processing. One of our aimed applications will be controlled single-photon storage and delay by generation of slow light within the strongly dispersive frequency regime between selected Cs-D1 resonances and storage via an off-resonant Raman-scheme. The second major goal of the project focuses at the manipulation of stored photons and the generation of higher-order photon number (Fock) states by using cesium atomic vapor in combination of highly excited Rydberg gas medium with controllably attractive or repulsive atom-atom interaction. A Rydberg gas can act e.g., as an optical transistor for two individual photons to merge into a common mode channel. The effect of photon-photon scattering can be controlled externally by an appropriate Rydberg pump laser for the atomic medium.