EAGER: CRYO: Refrigeration across temperature scales with electrically-tunable spin-orbit materials

EAGER：CRYO：利用电可调自旋轨道材料实现跨温标制冷

• 批准号: 2233111
• 负责人: Ravishankar Sundararaman
• 金额: $ 29.72万
• 依托单位: Rensselaer Polytechnic Institute
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2233111&HistoricalAwards=false
• 关键词: EAGER; CRYO; Refrigeration; across; temperature

Non-technical summaryQuantum computing and communication technologies, which will become increasingly critical for competitiveness and security in the next phase of the information age, require ultralow temperatures that are hundreds to thousands of times smaller than room temperature. Currently the predominant approach to reach such temperatures relies on repeatedly mixing and separating two isotopes of helium, He-3 and He-4, in a dilution refrigerator. However, helium in general, and He-3 in particular, are rare and increasingly expensive. This poses a severe challenge to the widespread adoption of quantum technologies. With this high risk/high reward project, supported by the Division of Materials Research, researchers at the Rensselaer Polytechnic Institute investigate a new approach for achieving ultralow temperatures without relying on rare elements. Specifically, they leverage the unique interactions of the spin of electrons in a class of materials called Rashba materials with electric fields. Preliminary simulations show that switching a voltage applied to these materials on and off in a specific pattern and direction may allow reaching low temperatures efficiently, making these potentially promising materials to compete with dilution refrigerators. In addition to enabling the widespread adoption of quantum technologies, the success of this new approach to reach very low temperatures could make a wide range of low-temperature phenomena, such as superconductors, more scientifically and technologically accessible. To educate the next generation of STEM workforce, the researchers integrate the underlying theory and experimental demonstrations of ultralow temperature refrigeration into undergraduate and graduate curricula as well as high-school outreach programs. This helps introduce future scientists and engineers to the technological challenges on the path to the age of quantum information.Technical summaryWith support from the Division of Materials Research, the researchers leverage Rashba spin-orbit coupling in materials as a new platform for enabling new approaches to reach ultralow temperatures down to 0.01 K, breaking the current dependency on the extremely rare He-3 isotope required by dilution refrigerators. They study new thermodynamic cycles that take advantage of the dependence of the electronic entropy on electric fields, due to the change of the spin-orbit splitting with electric field strength in Rashba materials. In particular, they investigate the possibility for refrigeration by adiabatic electrification of Rashba materials and determine if this can provide sufficient cooling power that matches or even exceeds that of typical dilution refrigerators. Research objectives include exploring a wide class of Rashba materials with different spin-orbit coupling strengths, synthesize structures capable of electric field cycling in these materials and quantify the field- and temperature-dependent thermodynamic parameters of these materials relevant for refrigeration. If successful, this approach may be extensible to a wide temperature range due to the broad range of Rashba energy splits, potentially opening up a pathway to cool from liquid nitrogen to millikelvin temperatures in a single material platform.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.

非技术摘要量子计算和通信技术对于信息时代下一阶段的竞争力和安全性将变得越来越重要，需要比室温小数百至数千倍的超低温。目前达到这样温度的主要方法依赖于在稀释制冷机中反复混合和分离两种氦同位素 He-3 和 He-4。然而，氦气，尤其是 He-3 非常稀有，而且越来越昂贵。这对量子技术的广泛采用提出了严峻的挑战。通过这个高风险/高回报的项目，在材料研究部的支持下，伦斯勒理工学院的研究人员研究了一种在不依赖稀有元素的情况下实现超低温的新方法。具体来说，他们利用了一种称为 Rashba 材料的材料中电子自旋与电场的独特相互作用。初步模拟表明，以特定模式和方向打开和关闭施加到这些材料的电压可能会有效地达到低温，从而使这些潜在有前途的材料能够与稀释制冷机竞争。除了能够广泛采用量子技术之外，这种达到极低温度的新方法的成功还可以使超导体等各种低温现象变得更容易在科学和技术上实现。为了教育下一代 STEM 劳动力，研究人员将超低温制冷的基础理论和实验演示融入本科生和研究生课程以及高中推广计划中。这有助于向未来的科学家和工程师介绍量子信息时代道路上的技术挑战。技术摘要在材料研究部的支持下，研究人员利用材料中的 Rashba 自旋轨道耦合作为新平台，以实现新方法达到低至 0.01 K 的超低温，打破了目前稀释制冷机所需的极其稀有的 He-3 同位素的依赖。他们研究了新的热力学循环，利用电子熵对电场的依赖性，这是由于 Rashba 材料中自旋轨道分裂随电场强度的变化而产生的。特别是，他们研究了通过 Rashba 材料绝热起电进行制冷的可能性，并确定这是否可以提供足以匹配甚至超过典型稀释制冷机的冷却能力。研究目标包括探索具有不同自旋轨道耦合强度的各种 Rashba 材料，合成能够在这些材料中进行电场循环的结构，并量化这些与制冷相关的材料的场和温度依赖性热力学参数。如果成功，由于 Rashba 能量分裂的范围广泛，这种方法可能会扩展到很宽的温度范围，从而可能开辟一条在单一材料平台中从液氮冷却到毫开尔文温度的途径。该奖项反映了 NSF 的法定使命，并具有通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。