Studies of Mesoscopic Metal Rings with Cantilever Magnetometers

* 非技术性摘要 * 虽然“人造原子”这个术语经常被应用于表现出量子效应的小型电子元件，但这种器件与真实的原子之间存在着重要的区别：真实的原子没有连接到电线上，也不是包括宏观室温电子器件在内的电路的一部分。原子是“封闭的”系统，它们与环境和/或测量仪器的相互作用非常微弱或非常间歇。该项目的目标是开发一种在更类似于真实的原子的环境中研究量子尺度电子器件的方法。微米级的电路（小到足以让量子效应变得重要）将被制造出来，并通过将它们放置在超灵敏微机械振荡器的末端来测量。因此，电路将被电隔离，并且将仅通过机械装置的运动被“读出”。预计这种方法将能够测量“持续电流”：即使在非超导金属中也没有耗散的电流。这些电流的性质是这一领域的一个突出的争议。持续电流直接探测电子之间的相互作用以及耗散环境对电子系统的影响。这些主题对我们理解多体物理和固态系统中的量子信息处理至关重要。因此，对持续电流进行结论性的实验研究将对广泛的科学领域和技术产生影响。从事该项目的学生和博士后将成为低噪声测量、低温学、微加工和微机械加工、真空和光学技术方面的专家。他们将做好充分准备，在未来的科学劳动力中占据一席之地。* 技术摘要 * 本项目的目标是使用微机械探测器来研究封闭的介观电子系统。该项目将把微米级电路集成到超灵敏悬臂梁中，并利用悬臂梁的响应来研究这些电路的量子特性。一个主要的目标将是澄清我们对正常金属中持续电流的理解。这些杠杆将被用作扭转磁力计，以研究各种尺寸和材料的环作为温度、磁场和电磁环境的函数。介观现象（例如持续电流）对磁性杂质和微波干扰非常敏感。因此，这些方面将是该项目的一个特别重点。从长远来看，悬臂梁的动力学将用于探测环的低位电子激发以及包含更复杂组件的环，如约瑟夫森结，量子点，纳米线或石墨烯。持续电流直接探测电子-电子相互作用和耗散环境对电子系统的影响。这些主题对我们理解多体物理和固态系统中的量子信息处理至关重要。因此，对持续电流进行结论性的实验研究将对广泛的领域产生影响。从事该项目的学生和博士后将成为低噪声测量、低温学、微加工和微机械加工、真空和光学技术方面的专家。他们将做好充分准备，在未来的科学劳动力中占据一席之地。

****NON-TECHNICAL ABSTRACT****Although the term "artificial atoms" is often applied to small electronic components which exhibit quantum effects, there is an important difference between such devices and real atoms: real atoms are not connected to wires and are not part of a circuit which includes macroscopic room-temperature electronics. Atoms are "closed" systems, which interact with their environment and/or measuring apparatus only very weakly or very intermittently. This project's goal is to develop a means for studying quantum-scale electronic devices in a setting much more analogous to that of real atoms. Micrometer-scale circuits (small enough for quantum effects to be important) will be fabricated and measures by placing them on the ends of ultrasensitive micromechanical oscillators. The circuits will thus be electrically isolated, and will be "read out" only by the motion of the mechanical device. It is expected this approach will enable the measurement of "persistent currents": currents that flow without dissipation even in non-superconducting metals. The properties of these currents are an outstanding controversy in this field. Persistent currents directly probe interactions between electrons and the effect of a dissipative environment on electronic systems. These topics are crucial to our understanding of many-body physics and quantum information processing in solid-state systems. As a result a conclusive experimental study of persistent currents would be of interest to a broad range of scientific fields and technology. Students and postdocs working on this project will become experts on low noise measurements, cryogenics, microfabrication and micromachining, vacuum, and optics techniques. They will be well prepared to take their place in the future scientific workforce. **** TECHNICAL ABSTRACT****The goal of this project is to use micromechanical detectors to study closed mesoscopic electronic systems. This project will integrate micron-scale circuits into ultrasensitive cantilevers and use the cantilever's response to study the quantum properties of these circuits. A primary goal will be to clarify our understanding of persistent currents in normal metals. The cantilevers will be used as torsional magnetometers to study rings of various sizes and materials as a function of temperature, magnetic field, and electromagnetic environment. Mesoscopic phenomena (such as persistent currents) are known to be very sensitive to magnetic impurities and microwave interference. Thus, these aspects will be a particular focus of the project. In the longer term, the cantilever's dynamics will be used to probe the rings' low-lying electronic excitations as well as rings incorporating more complex components such as Josephson junctions, quantum dots, nanowires, or graphene. Persistent currents directly probe electron-electron interactions and the effect of a dissipative environment on electronic systems. These topics are crucial to our understanding of many-body physics and quantum information processing in solid-state systems. As a result a conclusive experimental study of persistent currents would be of interest to a broad range of fields. Students and postdocs working on this project will become experts on low noise measurements, cryogenics, microfabrication and micromachining, vacuum, and optics techniques. They will be well prepared to take their place in the future scientific workforce.