Innovative experiments on quantum materials

量子材料是全世界非常密集的研究工作的核心。原因有二：在应用方面，对具有超导性等特性的材料有着巨大的需求（在没有能量耗散的情况下承载电流的可能性），特殊的光学特性（吸收某些波长同时反射其他波长的可能性）等。在基本面上，这些材料与上个世纪发展的概念和方法相抵触，这些概念和方法成功地解释了大多数材料的性质。理解其特殊性质的机制对凝聚态物理学来说是一个挑战：虽然我们知道在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涌现性质。对这些材料的理解也是开发基于其显着特性的设备的关键。 科学的进步是通过将理论预测与实验结果相对照来实现的。虽然有过多的常规使用的实验技术，我们建议开发新的实验来探测量子材料的一些有趣的特性，从而提供新的证据，在他们的理解进展。这些实验源自我们开发的类似实验，用于探测电路中电的量子性质，将揭示量子材料的神秘特性。在一系列的原始实验中，我们将：-研究材料的拓扑特性如何修改它们对入射微波的电磁响应（纵向和横向），可能在超低温和磁场的存在下。这对电子设备的发展至关重要。- 通过测量材料的频率依赖性微波响应来探测电子的温度依赖性散射时间，该材料具有普遍的特性-电阻率对温度的线性依赖性。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，从而获得电子的可压缩性。这个参数是理解物质神秘相的关键，比如铜氧化物中的赝隙相。- 利用微秒脉冲磁场中的时间分辨交流输运测量，观测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.