QMHP:: Decoherence, dissipation, entanglement and control in nanostructures.

QMHP：纳米结构中的退相干、耗散、纠缠和控制。在过去的十年里，电子设备变得越来越小，推动了技术的进步。为了提高计算机速度和计算机芯片的复杂性，需要更小的设备。继续这种趋势的可能性是有限的，因为技术已经接近达到原子水平。值得注意的是，在这个极限下，电子行为的不同规则，特别是量子现象，变得很重要。利用量子力学定律提供了利用量子力学相干性、电子波干涉和纠缠的机会。连接量子力学对象，这样一个对象就不能在不了解其对应对象的情况下被描述-用于开发新一代纳米器件。一个基本的挑战是理解和实现在电压下工作的器件中的量子现象，即在非平衡条件下，以及由于杂质原子在提供电荷载流子和定义电和磁性质方面发挥重要作用而存在的无序和波动。量子现象受到相干性损失（退相干）的限制，有必要确定损失的机制并找到控制它们的方法。退相干将定义未来信息技术系统中每比特信息的耗散。旨在从理论上理解退相干和耗散的科学努力将集中在三个相互关联的项目上：1)人工纳米级原子-量子点的功率吸收和拉比振荡（循环量子行为），2)硅量子点中自旋（固有量子角动量）和电荷的相干性损失，3)磁性半导体纳米结构的相干性和输运理论，它可能在单个器件中结合磁记忆和电子功能。智力优势：本研究有望阐明量子器件退相干的具体机制，并设计出控制退相干和耗散的方法。虽然这不是研究的唯一焦点，但结果可能有利于量子计算研究。考虑到强相关性和纠缠效应，该方法有望克服在电压存在下处理时间相关量子行为的正式挑战。预期的分析结果将有可能影响未来量子器件的建模。更广泛的影响：这项提议的研究对社会有潜在的好处，因为它旨在发展对如何减少信息的功耗的基本理解，这是一个与设备小型化一样重要的趋势。对教育的影响将包括面向研究生和高级本科生的纳米科学课程的课程开发，旨在培养未来的量子工程师，满足重要的社会需求。项目负责人和通过项目资助的博士后研究人员将积极参与项目项目与项目研究小组的研究生群体的讨论。一个与普渡大学物理系和伯克纳米技术中心网站相连的关于耗散和退相干的专题网站将集中于广泛传播预期的研究结果，以加强科学和技术的理解。

QMHP: Decoherence, dissipation, entanglement and control in nanostructures.Over the past decade, electronic devices have been getting smaller and smaller, driving the progress of technology. Smaller devices are desirable for improving computer speed and the complexity of computer chips. The possibility of continuing this trend is limited because technology is already close to reaching the atomic level. Remarkably, in this limit, different rules of electron behavior, particularly quantum phenomena, become important. Tapping the laws of quantum mechanics presents the opportunity of using quantum-mechanical coherence, interference of electronic waves, and entanglement ? linking of quantum mechanical objects so that one object cannot be described without knowledge of its counterpart - for developing a new generation of nanodevices.A fundamental challenge is the understanding and realization of quantum phenomena in devices which function under voltage, i.e., in non-equilibrium conditions, and in the presence of disorder and fluctuations due to impurity atoms that play an important role in supplying charge carriers and defining electric and magnetic properties. Quantum phenomena are limited by loss of coherence (decoherence), and it is necessary to identify mechanisms of losses and to find the means to control them. Decoherence will define dissipation per bit of information in future information technology systems.Scientific efforts directed at a theoretical understanding of decoherence and dissipation will be focused on three interconnected projects: 1) absorption of power and Rabi oscillations (cyclic quantum behavior) in artificial nanoscale atoms - quantum dots, 2) loss of coherence by spin (intrinsic quantum angular momentum) and charge in silicon quantum dots, 3) theory of coherence and transport in magnetic semiconductor nanostructures, which may combine magnetic memory and electronic functionalities in single devices.Intellectual merit: The proposed research holds a promise to elucidate specific mechanisms of decoherence in quantum devices and to devise methods to control decoherence and dissipation. Though not the sole focus of the work the results may benefit quantum computing research. The proposed approach promises to overcome formal challenges of treating time-dependent quantum behavior in the presence of voltage, taking into account strong correlations and entanglement effects. The expected analytical results will have a potential to affect the future modeling of quantum devices.Broader impacts: The proposed research has a potential benefit for society because it is aimed at developing a fundamental understanding of how to decrease power dissipation for bit of information, a trend as important as miniaturization of devices. The impact for education will include curriculum development in a nanoscience course for graduate students and advanced undergraduates, which aims at training of future quantum engineers, fulfilling an important societal need. Both the PI and a postdoctoral researcher funded via the proposed program will actively engage in discussions of the program projects with the diverse group of graduate students of the PI research group. A topical website on dissipation and decoherence linked to the Purdue Department of Physics and the Birck Nanotechnology Center websites will be focused on broad dissemination of the expected research results in order to enhance scientific and technological understanding.