Studies of Mesoscopic Metal Rings with Cantilever Magnetometers

*非技术摘要*虽然“人造原子”这个术语经常用于描述表现量子效应的小型电子元件，但这种装置与真实原子之间有一个重要的区别：真实原子不连接到导线，也不是包括宏观室温电子学的电路的一部分。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原子的环境中研究量子规模电子设备的方法。将制造微米级的电路(小到足以产生重要的量子效应)，并通过将它们放置在超灵敏微机械振荡器的末端进行测量。因此，电路将是电气隔离的，并且只有通过机械装置的运动才能被“读出”。预计这种方法将使测量“持续电流”成为可能：即使在非超导金属中流动的电流也不会消散。这些洋流的性质是这一领域的一个突出争议。持续电流直接探测电子之间的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，对持续电流进行决定性的实验研究将对广泛的科学领域和技术产生兴趣。从事这个项目的学生和博士后将成为低噪音测量、低温、微制造和微机械、真空和光学技术方面的专家。他们将做好充分准备，在未来的科学劳动大军中占据一席之地。*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。这个项目将把微米级的电路集成到超灵敏的悬臂中，并利用悬臂的响应来研究这些电路的量子特性。一个主要目标将是澄清我们对正常金属中持续电流的理解。悬臂将被用作扭转磁力计，以研究不同尺寸和材料的环随温度、磁场和电磁环境的变化。众所周知，介观现象(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，悬臂的动力学将用于探测环的低能电子激发，以及含有更复杂组件的环，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，对持续电流进行决定性的实验研究将会引起广泛领域的兴趣。从事这个项目的学生和博士后将成为低噪音测量、低温、微制造和微机械、真空和光学技术方面的专家。他们将做好充分准备，在未来的科学劳动大军中占据一席之地。

****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.