Innovative experiments on quantum materials

量子材料是世界范围内一项非常紧张的研究工作的核心。这样做的原因有两个：在应用方面，对具有超导性质(可能携带电流而不耗散能量)、特殊光学性质(吸收某些波长而反射其他波长的可能性)等性质的材料有巨大的需求。在根本方面，这些材料抵制上个世纪发展起来的概念和方法，以成功解释大多数材料的性质。对于凝聚态物理学来说，理解它们特殊性质的机制是一项挑战：虽然我们知道量子力学中正确描述物质的基本成分，但它们相互作用的复杂性导致了仍然难以理解的新兴性质。对这些材料的了解也是开发基于其卓越性能的设备的关键。科学的进步是通过将理论预测与实验结果对峙来实现的。虽然有太多常规使用的实验技术，但我们建议发展新的实验来探索量子材料的一些有趣的性质，从而为进一步了解它们提供新的证据。这些实验源于我们为探索电路中电的量子性质而开发的类似实验，将揭示量子材料的神秘性质。在一系列原创实验中，我们将：-研究材料的拓扑属性如何改变其对入射微波的电磁响应(纵向和横向)，可能是在超低温和磁场存在的情况下。这对电子设备的发展至关重要。-通过测量材料的频率依赖微波响应来探测电子随温度变化的散射时间，该响应表现出普遍的行为--电阻率与温度的线性关系。这对于验证高度相关材料的理论至关重要。-测量电子屏蔽静电场的方式，这使人们能够了解它们的电子可压缩性。这个参数是理解神秘物质相的关键，比如铜酸盐中的赝隙相。-使用微秒脉冲磁场中的时间分辨交流输运测量，观察超高场下的量子振荡。这将有助于阐明高温超导体的超导电性机制。

Quantum materials are at the heart of a very intense research effort worldwide. The reason for this is twofold: on the application side, there is a huge demand for materials with properties such as superconductivity (the possibility to carry current without energy dissipation), particular optical properties (the possibility to absorb certain wavelengths while reflecting others), etc. On the fundamental side, these materials resist concepts and methods developed in the last century to successfully explain the properties of most materials. Understanding the mechanisms responsible for their peculiar properties is a challenge for condensed matter physics: while we know the basic ingredients that correctly describe matter in quantum mechanics, the complexity of their interactions leads to emergent properties that are still difficult to understand. The understanding of these materials is also key to develop devices based on their remarkable properties. Science progresses by confronting theoretical predictions with experimental results. While there is plethora of routinely used experimental techniques, we propose to develop new experiments to probe some of the intriguing properties of quantum materials, thus providing new evidences to progress in their understanding. These experiments, derived from similar experiments we have developed to probe the quantum nature of electricity in circuits, will shed light on the mysterious properties of quantum materials. In a series of original experiments, we will: - Study how topological properties of materials modify their electromagnetic response (longitudinal and transverse) to an incident microwave, possibly at ultra-low temperature and in the presence of a magnetic field. This is critical to the development of electronic devices. - Probe the temperature-dependent scattering time of electrons by measuring the frequency-dependent microwave response of materials showing a universal behavior - the linear dependence of resistivity on temperature. This is essential to validate theories of highly correlated materials. - Measure the way electrons screen an electrostatic field, this giving access to their electronic compressibility. This parameter is key to the understanding of mysterious phases of matter such as the pseudogap one in cuprates. - Observe quantum oscillations at ultra-high field using a time-resolved ac transport measurement in a microsecond pulsed magnetic field. This will help elucidate the mechanism of superconductivity in high Tc superconductors.