Semiconductor quantum wells excited by non-classical states of light: Interplay between photonic quantum correlations and many-body interactions in solid state systems

与原子系统相比，体半导体和纳米结构的光学特性的理论描述要复杂得多，但也要丰富得多，并且可以通过纳米结构几何形状和材料成分的选择来设计广泛的范围，例如在量子阱中。原子中的电子态是局域的和离散的，而原子在晶格中的周期性排列导致了离域的布洛赫态和晶体的连续电子带结构。此外，在块状半导体和纳米结构中，如量子阱，电子之间的多体相互作用以及与其他准粒子（如声子）的多体相互作用非常强烈地影响它们的性质。这有几个重要的结果，如激子共振，它支配着带隙附近的线性光学吸收和多体相关，例如，双激子效应和由库仑散射和电子-声子散射引起的减相和弛豫过程，它们显著地改变了光学性质。几十年来，人们对半导体和半导体纳米结构的经典光场激发进行了大量的实验和理论研究。然而，关于与量子光相互作用的知识却少得多。现有的大多数文献都集中在发射特性上，例如，通过与真空场波动的耦合来描述自发光发射（发光），并且由于量子点作为单光子和纠缠光子对的按需源的潜力，因此特别关注量子点（所谓的人工原子，具有离散的受限电子态）。到目前为止，关于量子光激发半导体的研究很少，而且研究的都是比较简单的情况。通过这项联合提案，我们计划填补这一空白，并开发一种完全量子化和微观的理论方法，能够准确地描述半导体量子阱与复杂量子光的共振和近共振相互作用，特别是与明亮的压缩光。这种非经典光具有光子数分布广、光子间相关性强、噪声降低到短噪声水平以下以及存在高阶非零轨道角动量等特点。这种光与半导体的相互作用将为激发动力学带来新的特征，并允许将强量子相关性从场子系统转移到电子子系统，反之亦然。计划中的研究将有助于发现由于光子相关和相互作用子系统的相互影响而产生的半导体结构的新特征，为控制此类系统的电子输运和性质提供可能性，并导致新的物理现象及其实验可观察到的特征的预测。

Compared to atomic systems, the theoretical description of the optical properties of bulk semiconductors and nanostructures is significantly more complex but also much richer and over a wide range designable by the choice of the nanostructure geometry and the material composition, e.g., in quantum wells. Whereas in atoms the electronic states are localized and discrete, the periodic arrangement of atoms in a lattice results in delocalized Bloch states and the continuous electronic band structure of crystals. In addition, in bulk semiconductors and nanostructures like quantum wells many-body interactions among the electrons and with other quasi-particles like phonons very strongly influence their properties. This has several important consequences such as excitonic resonances which dominate the linear optical absorption near the band gap and many-body correlations, e.g., biexcitonic effects and dephasing and relaxation processes resulting from Coulomb scattering and electron-phonon scattering that significantly modify the optical properties.The excitation of semiconductors and semiconductor nanostructures with classical light fields has been studied very intensively for several decades both experimentally and theoretically. However, significantly less knowledge is available on the interaction with quantum light. Most of the existing literature focuses on the emission properties, e.g., the description of spontaneous light emission (luminescence) by the coupling to vacuum field fluctuations and much attention was in particular paid to quantum dots (so-called artificial atoms, with discrete confined electronic states) due to their potential for applications as on-demand sources for single photons and entangled photon pairs. Up to now, only very few studies exist on the excitation of semiconductors with quantum light for which rather simple cases were considered. With this joint proposal we plan to fill this gap and to develop a fully-quantized and microscopic theoretical approach able to accurately describe the resonant and near-resonant interaction of semiconductor quantum wells with complex quantum light, in particular with bright squeezed light. Such non-classical light is characterized by broad photon number distribution, strong correlations between photons, noise reduction below the shot-noise level, and presence of high-order non-zero orbital angular momenta. The interaction of such light with semiconductors will bring new features into the excitation dynamics and allows to transfer strong quantum correlations from the field subsystem to the electronic one and vice versa. The planned investigations will help to discover the novel features of semiconductor structures arising due to photonic correlations and mutual influence of interacting subsystems, give the possibility to control the electronic transport and properties of such systems and lead to predictions of new physical phenomena and their experimentally observable signatures.