Superconducting Circuits and Macroscopic Quantum States of Light and Sound

非技术总结该奖项支持理论凝聚态物理学的研究和教育。微波电路设计的最新发展，包括由超导体制成的类似晶体管的元件，使得超电流能够与微波发生强烈的相互作用。在足够低的温度下，超导体中的超电流携带电流而不耗散。 超导状态涉及大量电子的集体行为，这些电子一起可以表现出原子和分子世界典型的量子力学状态的性质，即使超导体本身是宏观物体。初步工作表明，由此产生的微波可以是固有的低噪音，有点类似于激光。这种微波源可用于量子通信目的。PI旨在从理论上理解由于这些强烈的光-电荷相互作用而产生的微波的性质。PI将与实验人员密切合作。在一个相关的推力PI将研究一个混合系统，其中超导晶体管元件耦合微波与纳米级，机械振动线。预期这种耦合将导致微波和耦合的机械振动的低固有噪声。这种振动纳米线装置可能使超灵敏力显微镜的发展成为可能。这两个项目的总体目标是了解如何产生具有明显量子力学特性的稳态大振幅微波和纳米机械运动，如超低振幅噪声，也称为“量子压缩”。" 参与该项目的研究生和高年级本科生将接受理论凝聚态物理学的培训。学生将受益于直接访问同事Rimberg教授实验室的实验结果，并将有助于解释实验。 技术总结该奖项支持理论研究和教育有关推进理解一类超导电路系统，强烈耦合微波光子库珀对运输和纳米机械运动。 该活动包括两个超导电路项目。其中一个项目将发展库珀对激光器的综合理论，特别是阐明所产生的微波腔光子的量子性质，并对最近和计划中的实验数据进行建模。另一个项目将开发相关的微波腔-库珀对电路系统的理论，该系统包括一个纳米机械谐振器，也正在实验中实现。这个最近提出的系统实现了微波腔光子和纳米机械能量量子-声子之间的超强耦合。该项目将特别解决涉及大平均声子数的机械谐振器的明显量子态的产生。理论研究将补充达特茅斯的同事Alex Rimberg教授的平行实验工作，该工作也得到了NSF的支持。该项目的目标是更好地了解如何产生稳定的微波量子源和涉及大平均光子和声子数的机械量子态。稳定的、可调的量子微波源可能会在量子通信中找到应用，而稳定的、连续产生的机械量子态可能会在超灵敏的位置检测中找到应用。该奖项支持培养一名研究生，以及参与理论凝聚态物理研究的高年级本科生，获得多体理论、介观量子物理、非线性动力学、量子光学和计算物理学。学生们还将有机会应用他们的理论模型来帮助解释Rimberg教授团队的实验数据。

NONTECHNICAL SUMMARYThis award supports research and education in theoretical condensed matter physics. Recent developments in the design of microwave circuits involving transistor-like elements made of superconductors have resulted in the ability to make electrical supercurrents interact strongly with microwaves. At sufficently low temperature, supercurrents in superconductors carry electricity without dissipation. The superconducting state involes the collective behavior of a large of electrons that together can exhibit properties of quantum mechanical states typical of the world of atoms and molecules even though the supercondutor itself is a macroscopic object. Preliminary work suggests that the resulting generated microwaves can be inherently low noise, somewhat akin to a laser. Such microwave sources may be useful for quantum communication purposes. The PI aims to develop a theoretical understanding of the nature of the microwaves that are generated as a result of these strong light-charge interactions. The PI will work in close collaboration with experimentalist. In a related thrust the PI will investigate a hybrid system where a superconducting transistor element couples microwaves with a nanoscale, mechanical vibrating wire. It is expected that this coupling will result in low inherent noise for the microwaves and coupled mechanical vibrations. This kind of vibrating nanowire device may enable the development of an ultasensitive force microscope. An overall goal of these two projects is to develop an understanding of how to generate steady-state, large amplitude microwave and nanomechanical motions that have manifestly quantum mechanical properties such as ultralow amplitude noise, otherwise known as "quantum squeezing." A graduate student and advanced undergraduate students involved in the project will receive training in theoretical condensed matter physics. The students will benefit from having direct access to experimental results from colleague Prof. Rimberg's lab, and will help in the interpretation of the experiments. TECHNICAL SUMMARYThis award supports theoretical research and education concerned with advancing understanding of a class of superconducting circuit systems that strongly couple microwave photons to Cooper pair transport and to nanomechanical motion. The activity comprises two superconducting circuit projects. One project will develop a comprehensive theory of the Cooper pair laser, in particular elucidating the quantum nature of the generated microwave cavity photons and modeling the data from recent and planned experiments. The other project will develop the theory for a related microwave cavity-Cooper pair circuit system that includes a nanomechanical resonator, also being realized in experiment. This recently proposed system achieves ultra strong coupling between the microwave cavity photons and nanomechanical energy quanta--phonons. The project will in particular address the generation of manifestly quantum states of the mechanical resonator involving large average phonon number. The theoretical investigation will complement a parallel experimental effort by Dartmouth colleague Prof. Alex Rimberg, also supported by the NSF. The goal of the project is to provide a better understanding of how to generate steady, quantum sources of microwaves and mechanical quantum states involving large average photon and phonon numbers. Robust, tunable sources of quantum microwaves may find application in quantum communication, while steady, continuously generated mechanical quantum states may find use in ultra sensitive position detection.This award supports the training of a graduate student, as well as advanced undergraduate students involved in the research in theoretical condensed matter physics, gaining expertise in such areas as many body theory, mesoscopic quantum physics, nonlinear dynamics, quantum optics, and computational physics. The students will also have opportunities to apply their theoretical models to help explain experimental data from Prof. Rimberg's group.