Quantized Phonon Conductance of One-dimensional Systems

摘要：固体的导电导热能力决定了其在微电子等新技术中的应用潜力。令人惊讶的是，量子物理学预测，在纳米尺度上，固体的载电和载热能力不会随着截面的减小而不断降低。这一量子理论已经在不同的实验中被反复验证，这些实验分别针对不同纳米结构中电子的载电和载热能力。相比之下，在多晶氮化硅纳米结构中，只有一个预测的载热能力量子行为的实验观察报告。为了响应对晶格热输运量子理论的进一步实验研究的呼吁，本项目将重点放在单个单壁碳纳米管的量子理论实验研究上，并使用独特的测量方法。这项研究的成功有望增强对凝聚态物理基本支柱的理解，并为扩大参与量子和热科学研究和技术发展提供教育和推广机会。技术摘要：在实验实现的纳米结构中，没有两能级缺陷的SWCNTs最接近理想的一维（1D）量子体系。这项工作的目标是推进一维纳米结构的固有热导的多探针测量，以准确检测量化声子电导，这已经被预测为swcnts在相对较高的温度下高达约10 K。这个温度范围比之前氮化硅纳米束研究所需的低于0.8 K的温度范围更有利于产生量化声子电导的明确实验证据。如果成功，SWCNTs的测量将建立检测和控制低维系统的量子化声子输运行为的实验能力。这种能力有望在凝聚态物理的基础领域推进实验研究的前沿。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical Abstract: The ability of a solid to conduct electricity and heat determines its application potential in new technologies such as microelectronics. Surprisingly, quantum physics predicts that the electricity- and heat- carrying capabilities of a solid at the nanometer scale do not reduce continuously with decreased cross-section. This quantum theory has been validated repeatedly in different experiments for both the electricity- and heat-carrying capabilities of electrons in different nanostructures. In comparison, there has been only one reported experimental observation of the predicted quantum behavior of the heat-carrying ability in a polycrystalline silicon nitride nanostructure. In response to a call for further experimental investigations of the quantum theory of lattice heat transport, this project is focused on experimental investigation of this quantum theory in individual single-walled carbon nanotubes with the use of a unique measurement method. Success of this research is expected to both enhance the understanding of a essential pillar of condensed matter physics and provide education and outreach opportunities for broadening the participation in quantum and thermal science research and technology developments. Technical Abstract: Free of two-level defects, SWCNTs are closest to an ideal one-dimensional (1D) quantum system among the nanostructures that have been experimentally realized. The goal of this work is to advance multiprobe measurements of the intrinsic thermal conductance of 1D nanostructures for accurate detection of the quantized phonon conductance that has been predicted for a SWCNT at a relatively high temperature up to about 10 K. This temperature range is much more conducive to producing unambiguous experimental evidence of quantized phonon conductance than the below-0.8 K temperature required for prior studies of silicon nitride nanobeams. If successful, the proposed measurements of SWCNTs will establish an experimental capability for detecting and controlling quantized phonon transport behaviors of low-dimensional systems. This capability is expected to advance the frontier of experimental research in a foundational area of condensed matter physics.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.