DFG-RSF: Quantum interferometry with interacting electronic systems

电子学最近取得的令人印象深刻的进展很大程度上是由于使用了低维纳米结构，如量子阱、量子线和量子环，以及由于电子设备不断小型化到纳米级。这些尺度上的物理是由量子相干性和量子干涉效应以及电子-电子相互作用的影响所控制的。干涉是量子相干现象的一种表现机制，同时也是探测相干性的工具。该项目的目标是研究强电子-电子相互作用如何改变量子干涉现象。一般认为，相互作用会导致消相，从而降低干扰模式的可见性。然而，另一方面，相互作用产生了新的、正在出现的自由度，而这些自由度反过来又会产生干扰。我们计划研究四种类型的新型量子系统：1)具有强相互作用的Aharonov-Bohm装置中的干涉；II)基于分裂库珀对的干涉仪；III)基于拓扑物质边缘模式构建的干扰电路；具有零能量马约拉纳束缚态的自旋（量子比特）系统中的干涉、编织和退相干。这些系统都有实际应用价值。例如，量子信息电路可能很快就需要尺寸小于相干长度的微小squid。另一方面，我们的项目将解决多体量子世界的基本问题，例如，强相互作用无序系统中多体定位的物理学。这是DFG-RSF在呼吁德国-俄罗斯物理和数学领域联合项目提案框架下的一个合作项目。该项目将与朗道理论物理研究所（ITP）的研究小组合作进行。资讯科技及创新技术计划团队的专业知识相结合，应能产生协同效应，确保项目的最佳实施。

Impressive recent progress in electronics is largely due to the use of low-dimensional nanostructures such as quantum wells, quantum wires and rings, as well as due to the continuous miniaturization of electronic devices down to nanoscales. Physics at these scales is governed by quantum coherence and quantum interference effects as well as by the effects of electron-electron interaction. Interference is a mechanism for manifestation of quantum-coherent phenomena and at the same time a tool to probe coherence.The goal of this project is to investigate how strong electron-electron interactions transform the phenomenon of quantum interference. The common wisdom is that interaction causes dephasing, thus reducing the visibility of interference patterns. Yet on the other hand, interaction gives rise to new, emerging degrees of freedom, which, in turn, can interfere. We plan to investigate novel quantum systems of four types: I) Interference in Aharonov-Bohm setups with strong interaction; II) Interferometers based on split Cooper pairs; III) Interference circuits built out of edge modes in topological matter; IV) Interference, braiding and decoherence in spin (qubit) systems with zero-energy Majorana bound states. All these systems can find practical applications. For example, tiny SQUIDs of dimensions smaller than the coherence length might soon be needed in quantum-information circuits. On the other hand, our project will address the fundamental questions of many-body quantum world, e.g., the physics of many-body localization in strongly interacting disordered systems. This is a cooperation DFG-RSF project in the framework of the call for joint German-Russian project proposals in the field of physics and mathematics. The project will be carried out in collaboration with the research team of the Landau Institute for Theoretical Physics (ITP). Combination of the expertise of the KIT and ITP teams should lead to a synergy effect ensuring the best possible implementation of the project.