Théorie et simulations par ordinateur des matériaux quantiques et de la supraconductivité/ Theory and computer simulations of quantum materials and superconductivity

许多现代技术都归功于我们对材料电学性质的深刻理解。这种理解植根于交织在一起的经验、实验和理论知识。我致力于材料电子性质的理论方面的工作，换句话说，我设计和求解数学模型，并进行大规模的计算机模拟，以了解传统理解之外的新材料。在高温超导体等材料中，与通常情况相反，电子之间的相互作用如此强烈，以至于它们实际上不愿携带电流；它们应该处于绝缘状态。正是通过化学手段略微改变了电子的数目，才导致了一种新型的超导电性，这种超导电性发生在比通常温度高得多的温度。在过去的几年里，在新材料、新的理论理解和新的壮观实验方面取得了几项突破。我们为一些理论突破做出了贡献。我们相信我们能够回答这样的问题：什么是适当的数学工具来预测同时表现出局域(磁性)和传播(超导)特征的电子系统的行为？我们能否使用这些工具来证明存在新的基本激发或概念(伪隙)，这些概念可以简单地总结和解释这些系统的反常性质(即找到将起到“空穴”概念对半导体工业所做的作用的概念)？我们也可以在相关的材料类别中使用这些概念吗？高温超导的起源是什么？回答这些问题应该有助于我这个领域的人开发出可能具有其他惊人的和技术上有用的磁性或电学特性的材料，并展示新的物质相。回答这些问题也将有助于寻找在室温下表现出超导电性的材料。由于超导在宏观上表现出量子性质，从长远来看，可以预见到诸如量子计算机等革命性技术的诞生，以及相应的新产业。

Much of modern technology owes to our deep understanding of electronic properties of materials. That understanding is rooted in intertwined empirical, experimental and theoretical knowledge. I work on the theoretical aspects of electronic properties of materials, in other word I design and solve mathematical models and perform large scale computer simulations to understand new materials that escape conventional understanding. In materials such as high temperature superconductors, contrary to the usual case, the electrons interact so strongly with each other that they would in fact prefer not to carry electricity; they should be in an insulating state. It is by changing slightly the number of electrons by chemical means that one is lead to a new type of superconductivity that occurs at much higher temperature than usual. In the last few years several breakthroughs have occurred, in terms of new materials, new theoretical understanding and new spectacular experiments. We contributed to some of the theoretical breakthroughs. We believe that we are in a position to answer questions such as: What are the appropriate mathematical tools to predict the behavior of electronic systems that show both localized (magnetic) and propagating (superconducting) character? Can we use these tools to show that there are new elementary excitations, or concepts (pseudogap) that could summarize and explain in a simple way the anomalous properties of these systems (i.e. find concepts that will do what the concept of "holes" did for the semiconductor industry)? Can we also use these concepts in related classes of materials? What is the origin of high temperature superconductivity? Answering such questions should help people in my field to develop materials that may have other striking and technologically useful magnetic or electrical properties and also exhibit new phases of matter. Answering such questions will also help in the quest for materials that could exhibit superconductivity at room temperature. Since superconductivity manifests quantum properties on a macroscopic scale, one can foresee in the long run the birth of revolutionary technologies, such as the quantum computer, and corresponding new industries.