CAREER: Towards in situ control of BCS-BEC crossover in solid state systems

职业生涯：实现固态系统中 BCS-BEC 交叉的原位控制

• 批准号: 2239171
• 负责人: Yu He
• 金额: $ 73.48万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2028-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2239171&HistoricalAwards=false
• 关键词: CAREER; Towards; situ; control; BCS

Non-technical abstractAmong the biggest triumphs of quantum mechanics was the discovery of macroscopic quantum states - billions of electrons spontaneously fall into the same quantum state without any central coordination. One of the most prominent examples is superconductivity, where many electron pairs coherently move through the material without any resistance hence generating no heat loss. There are two ways for this to occur: two electrons first tightly bind into a molecule, then develop coherence with other molecules; or many electrons develop pairing and binding all at once. These two regimes are two limiting cases of how macroscopic coherent states can form, which are widely seen and used in cornerstone modern technologies such as lasers, superconducting qubits, and supermagnets. This project aims to realize tunable materials straddled between these two limits, exploring novel states of matter and their electronic structure during this crossover. Students from local middle and high-schools will be engaged in this project through interactive lectures and demonstrations of superconductivity and lasing. Local college undergraduate and graduate students will co-develop the curriculum and co-lead the sessions with the research team for broader participation.Technical abstractBardeen-Cooper-Schrieffer (BCS) mechanism and Bose-Einstein Condensate (BEC) are two limiting scenarios of one continuous route to realize macroscopic quantum coherent state of interacting fermions, where all particles in a system simultaneously occupy the same many-body ground state. Incarnated in solid state systems, these limiting scenarios can drive metal-to-superconductor and metal-to-insulator phase transitions. Despite immense theoretical interest, experimental realization of this crossover in solid state systems is scarce and controversial. In this research, the team aims to realize, understand, and tune BCS-BEC crossover in novel bulk and thin film solid state model systems, with a special emphasis on thermodynamic and spectroscopic investigations as the systems are tuned in situ through the crossover. This project not only sheds light on the crucial role of the wave function "phase" in macroscopic quantum states, but also develops new material platforms and novel thermodynamic techniques to investigate the phenomenon in both three and quasi-two dimensions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

非技术抽象的量子力学最大的胜利是发现宏观量子状态 - 数十亿电子自发地陷入相同的量子状态而没有任何中央协调。最突出的例子之一是超导性，其中许多电子对在材料中连贯地移动而没有任何阻力，因此不会产生热量损失。发生这种情况有两种方法：两个电子首先紧密结合到一个分子中，然后与其他分子发展一致。或许多电子一次都会产生配对和绑定。这两个制度是两个限制案例，表明宏观相干状态如何形成，这些状态被广泛看到并用于基石现代技术，例如激光器，超导码头和超级磁铁。该项目旨在实现跨越这两个限制之间的可调节材料，探索在此跨界期间的物质及其电子结构的新状态。来自当地中学和高中生的学生将通过互动讲座以及超导性和激光的演示参与该项目。 Local college undergraduate and graduate students will co-develop the curriculum and co-lead the sessions with the research team for broader participation.Technical abstractBardeen-Cooper-Schrieffer (BCS) mechanism and Bose-Einstein Condensate (BEC) are two limiting scenarios of one continuous route to realize macroscopic quantum coherent state of interacting fermions, where all particles in a system simultaneously占据相同的多体基础状态。这些限制场景在固态系统中被化身，可以驱动金属到超导体和金属到绝缘体相变。尽管理论上的兴趣极大，但在固态系统中，这种交叉的实验实现却很少且有争议。在这项研究中，该团队旨在在新型的大体积和薄膜固态模型系统中实现，理解和调整BCS-BEC交叉，并特别强调热力学和光谱研究，因为通过交叉点进行了系统调整。该项目不仅阐明了宏观量子状态中波函数“阶段”的关键作用，而且还开发了新的材料平台和新型的热力学技术，以调查三个和quasi-two维度的现象。该奖项颁发了NSF的法定任务，并反映了通过评估构成的构成商品的支持，并反映了构成的依据。

项目成果

Bogoliubov quasiparticle on the gossamer Fermi surface in electron-doped cuprates

电子掺杂铜酸盐中游丝费米表面上的 Bogoliubov 准粒子

• DOI: 10.1038/s41567-023-02209-x
• 发表时间: 2023
• 期刊: Nature Physics
• 影响因子: 19.6
• 作者: Xu, Ke-Jun;Guo, Qinda;Hashimoto, Makoto;Li, Zi-Xiang;Chen, Su-Di;He, Junfeng;He, Yu;Li, Cong;Berntsen, Magnus H.;Rotundu, Costel R.
• 通讯作者: Rotundu, Costel R.