Collective quantum transport and light-assisted superconductivity

当代凝聚态物理学是当今电子技术的基础。当与光学设备合并时，它代表着现代超高速设备的强大平台。与此同时，在这两个领域的边界上，固态系统与光强烈耦合的多种现象仍有待探索，并可能包含尚未发现的基本效应。特别是，强光-物质耦合的区域出现在纳米结构中，在光学谐振器中放置了明显的激子共振，在那里出现了被称为腔极化子的混合光-物质准粒子。极化电子学是一个发展迅速的领域，但迄今为止，人们主要忽略了极化电子学中的一个方面，即准粒子的相应量子统计性质以及由此产生的量子关联。当极化子的物质部分由服从费米统计的电子和空穴组成的激子表示时，光部分由服从玻色统计的腔光子构成。此外，在器件上增加额外的层，可以发挥纯粹的费米子物种-电子-发挥作用。在玻色-费米混合物的物理学背景下，新型二维材料-以原子薄的过渡金属二卤化物和石墨烯为突出例子-结合了许多理想的特性，从强烈的光学响应到相对简单和低制备成本，并允许创建由一个或几个孤立的层组成的结构，其中包含不同统计数据的粒子。这两个概念上不同的统计之间的相互作用为极化电子学领域带来了新的转折，并为观察其他类型的系统所不能获得的新的量子集体相提供了机会。在这个项目中，我们将探索在强光-物质耦合区域中，如何出现由混合量子统计效应产生的大的光学非线性和强量子关联。建议的研究包括超流、关联、阻力效应和超导电性，在微腔中的电子和极化电子的多层系统中，随着有利于观察创纪录的光学非线性、集体量子输运和光辅助超导行为的特殊几何设计的发展。为了实现这个将理论和实验紧密联系在一起的雄心勃勃的项目目标，我们聚集了一个强大的德国-俄罗斯学术联盟，在极化电子学和二维材料领域。国际团队联合了世界领先的理论家，他们将建立层状几何结构的固态玻色-费米混合物的微观理论，以及开发新结构和观察所提出的现象所需的无与伦比的实验设备。

Contemporary condensed matter physics is a foundation of the present-day electronics and technology. When merged with optics, it represents a powerful platform for modern ultrafast devices. At the same time, multiple phenomena lying at the border of these two realms, where solid-state systems are strongly coupled to light, are still to be explored, and potentially contain fundamental effects yet to be discovered. In particular, the regime of the strong light-matter coupling appears in nanostructures with pronounced excitonic resonance placed inside an optical resonator, where hybrid light-matter quasiparticles, known as cavity polaritons, emerge. Polaritonics is a rapidly developing field, however, one aspect in polariton physics, namely, corresponding quantum statistical properties of quasiparticles and resulting quantum correlations, was mainly overlooked up to now. While the matter part of a polariton is represented by an exciton, made from an electron and a hole that obey Fermi statistics, the light part is formed by a cavity photon obeying Bose statistics. Furthermore, adding extra layers to the device, one can bring purely fermionic species – electrons – into play.In the context of the physics of Bose-Fermi mixtures, novel two-dimensional materials – with prominent examples of atomically-thin layers of transition metal dichalcogenides and graphene – combine many desirable properties, from strong optical response to relative simplicity and low cost of preparation, and allow to create the structures consisting of one or several isolated layers hosting particles with different statistics. The interplay between the two conceptually different statistics brings a new twist into the domain of polaritonics, and presents an opportunity for observation of novel quantum collective phases unattainable in other kind of systems. In this project, we will explore how large optical nonlinearities and strong quantum correlations, stemming from the effects of the hybrid quantum statistics, appear in the regime of the strong light-matter coupling. Proposed studies include superfluidity, correlations, drag effects and superconductivity in such multi-layer systems of electrons and polaritons in a microcavity, with the development of specific designs of geometries favorable for the observation of record-high optical nonlinearities, collective quantum transport, and light-assisted superconducting behavior.To achieve the ambitious goals of this project that closely entwines theory and experiment, we bring together a strong German-Russian academic consortium in the field of polaritonics and two-dimensional materials. The international team unites world-leading theoreticians who will build the microscopic theory of solid-state Bose-Fermi mixtures in layered geometries, and unmatched experimental facilities necessary to develop the novel structures and observe the proposed phenomena.