Quantum and Classical Phenomena in Electrical and Mechanical Resonators

****技术摘要****本基金支持的研究将通过研究由宏观振荡器与微观电子设备强耦合组成的系统来研究经典物理和量子物理之间边界的本质。微观器件将由电信号驱动，然后观察其对宏观振荡器的影响（或反作用）。设想了两个系统：一个是微观部分是量子点接触（半导体中的微观电收缩），振荡器是嵌入点接触的宏观晶体。在另一种情况下，微观部分是一个单库珀对晶体管（一种将库珀对逐个传输的超导装置）与超导微波谐振器耦合。在每种情况下，对微观器件施加电驱动预计会导致宏观振荡器的振荡。对这种相互作用的详细研究可以更好地理解量子和经典行为之间的界面。本项目将资助两名研究生，对其进行微波测量、纳米尺度制造和低温物理等在学术界和高科技行业中广泛应用的实验技术的培训。****非技术摘要****众所周知，像棒球或行星这样的宏观物体的物理行为是由牛顿提出的经典物理定律非常准确地描述的，许多人从大一物理课程中熟悉这些定律。同样众所周知的是，像原子和分子这样的微观物体的行为是由更加神秘和违反直觉的量子物理定律来描述的。目前尚不清楚的是，经典行为和量子行为之间的界限究竟在哪里。为了调查这个问题，这项研究将检查由两部分组成的系统的行为，其中一部分本身将表现为经典行为，另一部分将表现为量子力学行为。通过设计，这两个部分将彼此强烈地相互作用，因此组合系统的行为将不同于单独的任何一部分。这类研究将更好地划定经典物理学和量子物理学之间的界限，并帮助我们理解量子现象对我们周围日常世界的影响。本项目将资助两名研究生，对其进行微波测量、纳米尺度制造和低温物理等在学术界和高科技行业中广泛应用的实验技术的培训。

****Technical abstract****The research supported by this grant will investigate the nature of the boundary between classical and quantum physics by study of systems consisting of a macroscopic oscillator strongly coupled to a microscopic electrical device. The microscopic device will be driven by application of an electrical signal, and its effects (or backaction) on the macroscopic oscillator will then be observed. Two systems are envisioned: in one the microscopic part is a quantum point contact (a microscopic electrical constriction in a semiconductor) and the oscillator is the macroscopic crystal in which the point contact is embedded. In the other, the microscopic part is a single Cooper pair transistor (a superconducting device that transfers Cooper pairs one by one) coupled to a superconducting microwave resonator. In each case, applying an electrical drive to the microscopic device is expected to lead to oscillations in the macroscopic oscillator. A detailed study of this interaction could lead to a better understanding of the interface between quantum and classical behavior. Two graduate students will be supported by this project, and will be trained in such experimental techniques as microwave measurement, nanoscale fabrication and low-temperature physics that are widely used both in academia and in high-technology industry.****Non-technical abstract****It is well understood that the physical behavior of macroscopic objects like baseballs or planets is described very accurately by the laws of classical physics developed by Newton and familiar to many from a course in freshman physics. It is equally well understood that the behavior of microscopic objects like atoms and molecules is described by the much more mysterious and counterintuitive laws of quantum physics. What is not clear is exactly where the boundary between classical behavior and quantum behavior lies. In order to investigate this question, this research will examine the behavior of systems made up of two pieces, one that by itself would behave classically, and another that on its own would behave quantum mechanically. By design, the two pieces will interact strongly with each other, so that the behavior of the combined system will be different from that of either piece in isolation. Investigations of this sort will better delineate the border between classical and quantum physics, and help us understand the influence of quantum phenomena on the everyday world around us. Two graduate students will be supported by this project, and will be trained in such experimental techniques as microwave measurement, nanoscale fabrication and low-temperature physics that are widely used both in academia and in high-technology industry.