Search for novel collective phenomena due to many-body correlations in low dimensional systems

寻找低维系统中多体相关性引起的新集体现象

• 批准号: RGPIN-2019-05486
• 负责人: Maiti, Saurabh
• 金额: $ 1.75万
• 依托单位: Concordia University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=738326
• 关键词: Search; novel; collective; phenomena; due

Low dimensional systems are interesting class of systems exhibiting novel quantum phenomena. Some examples that has created a lot of buzz are unconventional superconductors and Graphene-based materials. They offer great promise for the future by aiding in discovery on novel quantum phases (involving magnetism, density waves, superconductivity and even coexistence amongst them); and replacing electronics with Spintronics: a more efficient means to transfer information. Another unavoidable ingredient in low dimensional systems is the spin-orbit coupling that breaks parity. When combined with superconductivity it can lead to exotic excitations like Majorana fermions which are essential for quantum computing. However, much of the excitement has been at the level of single-particle physics. This does not allow us to exploit the benefits of the quantum world to the fullest potential. To do that one needs to understand the role of many-body correlations in such systems. This research program is designed to achieve precisely that in a very systematic manner by studying collective excitations in various low-dimensional systems. Collective excitations in general have the potential to tell us a great deal about a system provided we are equipped with a theory that can appropriately handle correlations. As part of this program, we will investigate the role of electronic correlations on spin-orbit coupled single/bilayer Graphene grown on transition metal dichalcogenides. It provides us with the opportunity to investigate collective excitations from non-spin degrees of freedom like sublattice, valley, and layer. We will further investigate collective excitations in the various quantum phases expected around the unconventional superconductivity phase like nematic, coexistence of nematic with superconductivity, magnetic and its coexistence with superconductivity. We will also provide the theory of Raman spectrum in all of these phases. Experimentally tracking the modes across the phase-boundaries using our theoretical model will provide improved insight into the nature of correlations present in the system. This program is designed to develop theoretical tools to handle many-body correlations in spin-orbit coupled systems: an important step forward in studying more complex phases of matter and incorporating many-body effects into fields like Spintronics and quantum computation. Several groups stand to benefit from the output of this program: it directly impacts groups working on Graphene-based devices; the high Tc community can benefit from the fact that different pairing mechanisms that predict similar ground-states, can now be distinguished as the collective excitations are different in each case; many of the conclusions we form in this program can also be tested using cold-atom set-ups thereby encouraging experiments in that field; the knowledge of collective excitations is also a stepping stone towards gauging the properties of non-equilibrium systems.

低维系统是一类有趣的系统，表现出新颖的量子现象。一些引起轰动的例子是非传统超导体和石墨烯材料。它们为未来提供了巨大的希望，因为它们有助于发现新的量子相(涉及磁性、密度波、超导电性，甚至它们之间的共存)；并用自旋电子学取代电子：一种更有效的信息传输手段。低维系统中另一个不可避免的因素是打破宇称的自旋-轨道耦合。当它与超导电性结合在一起时，可能会产生像Majorana费米子这样的奇异激发，这对量子计算是必不可少的。然而，令人兴奋的大部分是在单粒子物理层面上。这不允许我们最大限度地利用量子世界的好处。要做到这一点，我们需要了解多体关联在这类系统中的作用。这项研究计划旨在通过研究各种低维系统中的集体激发，以非常系统的方式精确地实现这一点。集体激发通常有可能告诉我们关于一个系统的许多信息，前提是我们配备了一个可以适当处理相关性的理论。作为本计划的一部分，我们将研究电子关联对生长在过渡金属二卤化物上的自旋-轨道耦合的单层/双层石墨烯的作用。它为我们提供了研究非自旋自由度的集体激发的机会，如亚晶格、谷子和层。我们将进一步研究非常规超导相周围的各种量子相中的集体激发，如向列相、向列相与超导共存、磁及其与超导共存。我们还将提供所有这些阶段的拉曼光谱理论。使用我们的理论模型通过实验跟踪相边界上的模式将提供对系统中存在的关联的本质的更好的洞察。该计划旨在开发理论工具来处理自旋-轨道耦合系统中的多体关联：在研究更复杂的物质相并将多体效应纳入自旋电子学和量子计算等领域方面迈出了重要的一步。有几个小组将从这个计划的输出中受益：它直接影响到工作在石墨烯设备上的小组；高TC社区可以受益于这样一个事实，即预测类似基态的不同配对机制现在可以被区分，因为集体激发在每种情况下是不同的；我们在这个计划中形成的许多结论也可以使用冷原子设置进行测试，从而鼓励该领域的实验；集体激发的知识也是测量非平衡系统性质的踏脚石。