****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.
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.
