RUI: Trapped Ion Phononics: Thermal Rectification and Controlled Heat Flow in 1D Ion Chains

自然界中的能量流动有多种形式：电流，瀑布在白内障上的水，来自遥远星球的光，或者泄漏到冷却器中的热量，破坏了一个人的野餐午餐。在这些机制中，对我们的日常生活最重要的机制是热传导和电传导。一个世纪以来的技术进步，如电子二极管和晶体管的发展，使人类能够精确地控制电流，并推动了今天的信息革命。相比之下，我们对热流的掌握--主导着美国90%的能源生产--仍处于初级阶段，但掌握对热流的控制可以实现从热逻辑门到提高光伏发电效率的各种应用。该项目的重点是开发一个利用激光冷却离子链控制热电流的基本构件之一的热敏二极管的原理验证示例。这样的链还将使在量子和经典制度的交叉处研究介观热导率成为可能，这对于理解微观设备中的热流是相关的。这项工作将在一所本科院校进行；学生将参与实验的各个方面，并在期刊论文和科学会议上发表报告，所有这些都将为未来的科学职业生涯提供极好的培训。这项工作的中心目标将是展示一种由共捕获的钙和锶离子形成的双离子热整流器。通过将两个离子耦合到激光冷却形成的不同有效温度下的热库，热流将从“热”离子流向“冷”离子。然后，通过基于激光的快速测温技术，利用离子的暗共振，可以从离子中提取热电流。整流的标志将是水库交换下的热流不对称。具有可控引入无序的更长的双物种链也将使使用类似技术研究整个链上的温度梯度的开始成为可能。所有这些工作将在教育的各个阶段为大量本科生提供研究培训，特别强调在本科早期吸引不同群体的学生。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Energy flow in the natural world takes many forms: electrical currents, water cascading over a cataract, light arriving from distant stars, or heat leaking into a cooler to ruin one's picnic lunch. Of these, the mechanisms of greatest practical importance for our daily lives are thermal and electrical conduction. A century of technological advances, such as the development of electrical diodes and transistors, have given humanity exquisite control over electrical currents and driven today's information revolution. In contrast, our command of thermal currents - which govern 90% of energy production in the United States - remains in its infancy, yet mastering control over thermal currents could enable applications ranging from thermal logic gates to improved efficiency from photovoltaic power generation. This project focuses on developing a proof-of-principle example of a thermal diode, one of the basic building blocks for controlling thermal currents, using laser-cooled ion chains. Such chains will also enable the study of mesoscopic thermal conductivity at the crossover between quantum and classical regimes, relevant for understanding thermal currents in microscopic devices. The work will take place at an undergraduate institution; students will be involved in all aspects of the experiments and their presentation in journal articles and at scientific conferences, all of which will provide superb training for future careers in the sciences.The central goal of this work will be to demonstrate a two-ion thermal rectifier formed from co-trapped calcium and strontium ions. By coupling the two ions to thermal reservoirs at different effective temperatures formed by laser cooling, a thermal current will flow from the `hot' to the `cold' ions. The thermal current can then be extracted from the ions via laser-based fast thermometry techniques utilizing the ions' dark resonances. The sign of rectification will be an asymmetry in the thermal current under exchange of the reservoirs. Longer dual-species chains with controllably introduced disorder will also enable the study of the onset of thermal gradients across the chain using similar techniques. All of this work will provide research training to a large number of undergraduate students at all stages of their education, with a special emphasis on engaging a diverse group of students early in their undergraduate years.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.