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

提出的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，这些概念和方案通过单个半导体量子点（QDs）和碱原子蒸气作为控制介质发射的光子之间的不同相互作用来控制产生和/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量子点（InGaAs）产生光谱窄带共振荧光（RF）作为光子源，可以与原子铯（133Cs）在~894 nm （D1超精细结构四重态）的光学共振进行受控相互作用。复杂的量子点原子相互作用实验的一个重要先决条件将是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）相互作用的效率将主要取决于光子源和热原子气体的光谱响应特性之间的相互光谱相似性，并以多普勒展宽为主，作为控制介质。因此，另一个非常重要的方面将是获得对射频发射线宽的灵活控制，以便根据原子跃迁调整其带宽。在这个项目中，我们计划利用不同的调节技术，即(a)确定的pi脉冲光学量子点激发，(b)在弱激发体制（希特勒体制）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RF，以及(c)从pi脉冲体制和饱和以上的w-dressed发射体制中对单量子点RF进行光谱后滤波。这可以通过使用专门设计的高精细度的fabry - p<s:1>干涉仪来实现，或者首次将fadof型（法拉第反常色散光学滤波器）传输滤波技术与QD-RF相结合来实现。利用这种条件光子，该项目的预期目标集中于光量子信息处理领域的基础应用。我们的目标应用之一是控制单光子的存储和延迟，通过非谐振拉曼方案，在选择的Cs-D1共振和存储之间的强色散频率范围内产生慢光。该项目的第二个主要目标是利用铯原子蒸气与高激发里德伯气体介质结合，利用可控的吸引或排斥原子-原子相互作用，操纵存储的光子和产生高阶光子数（Fock）态。例如，里德伯气体可以作为光学晶体管，使两个单独的光子合并到一个共模通道中。光子-光子散射效应可以通过对原子介质使用合适的里德伯泵浦激光器进行外部控制。

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.