Calorimetry and Thermal Transport at the Quantum Limit

w：\awards\awards96\num.doc 9705411 Roukes 量子极限下的量热法和热输运。 这项新的研究计划的重点是降维热流 和 热 纳米结构中的平衡。 研究人员已经开发出用于悬浮半导体结构的表面纳米加工的新技术，这些结构能够构建微型热隔离器件。 这些 具有集成的传感器， 局部引入热量和局部温度测量。 耦合这些与高灵敏度的直流SQUID为基础的方法，在毫开尔文温度下的电子测温，最终预计将产生足够的灵敏度，探索涉及个人量子的能量交换过程。单声子现象，与经典光学和量子光学中的类似现象，应该是可以观察到的. 有趣的可能性包括声子散粒噪声，声子聚束，与电子-声子弛豫相关的电子-声子弛豫，以及准孤立的声子-声子能量衰减。 热储层 与 这 水平 灵敏度，量热实验阐明 涉及单个原子和分子的过程也是可能的。 %%% 量子极限下的量热法和热输运。 这项新的研究计划集中在热如何流动的问题上 在 极小的物体，即 纳米结构。 超小 系统可以表现得好像 降维（即， 小于3D）。 在低温下，对于 足够小，热流 和 热平衡将最终发生， 交换 单个能量量子。这个领域，其中热传递是“颗粒状”的（传递量子的量子，而不是作为一个稳定的流动）仍然完全未被探索。完全理解 这些问题将随着导致纳米技术的器件的持续结晶化而变得至关重要。 这些研究现在可以通过研究人员开发的新纳米加工技术来实现，允许创建具有三维浮雕的悬浮超小型半导体结构-带有板载电子测量电路。 在这项研究的可能应用中，这些实验应该能够直接观察涉及单个原子的化学反应过程中产生的热量， 分子。 开发的设备还应 为光学测量提供前所未有的灵敏度 和红外辐射。 ***

w:\awards\awards96\num.doc 9705411 Roukes Calorimetry and Thermal Transport at the Quantum Limit. This new research program focuses on reduced-dimensional heat flow and thermal equilibration in nanostructures. The investigators have developed new techniques for the surface nanomachining of suspended semiconductor structures that enable the construction of miniature, thermally-isolated devices. These possess integral transducers permitting the local introduction of heat, and local temperature measurements. Coupling these with high sensitivity dc SQUID-based methods for electron thermometry at millikelvin temperatures is ultimately expected to yield sensitivity sufficient for exploration of energy exchange processes involving individual quanta. Single- phonon phenomena, with analogs in classical and quantum optics, should become observable. Intriguing possibilities include phonon shot noise, phonon bunching, anticorrelated electron- phonon relaxation, and the phonon-by-phonon energy decay of a quasi-isolated thermal reservoir. With this level of sensitivity, calorimetry experiments elucidating processes involving individual atoms and molecules are also possible. %%% Calorimetry and Thermal Transport at the Quantum Limit. This new research program focuses on the question of how heat flows in extremely small objects, i.e. nanostructures. Ultrasmall systems can behave as if they are reduced- dimensional (i.e., less than 3D). At low temperatures, for systems that are small enough, heat flow and thermal equilibration will ultimately occur by the exchange of individual energy quanta. This domain, where heat transfer is "granular" (delivered quanta-by-quanta rather than as a steady flow) remains completely unexplored. A complete understanding of these issues will become crucial with the continued miniaturi zation of devices leading to nanotechnology. These studies are now possible through new nanomachining techniques developed by the investigators, allowing the creation of suspended, ultrasmall semiconductor structures with three- dimensional relief -- with on-board electronic measurement circuitry. Among possible applications of this research, these experiments should enable direct observation of the heat evolved during chemical reactions involving *individual* atoms and molecules. The devices developed should also offer unprecedented sensitivity for measurement of optical and infrared radiation. ***