ITR: Advances of Simulation Algorithm of Quantum Manybody Transport in Steady State Nonequilibrium

该奖项是根据信息技术研究招标NSF-04-012提交给材料研究部的提案而颁发的。该奖项涵盖的研究活动属于国家优先领域，“科学与工程的进步”和技术重点领域，“计算建模或模拟研究的创新”。该奖项支持量子点和纳米结构中非平衡传输的基础计算和理论研究。在纳米尺度上，高偏压非平衡和量子多体效应紧密耦合，传统的半导体器件输运理论变得不适用。PI将开发稳态非平衡系统的量子模拟算法。量子蒙特卡罗模拟将被用来采样稳态非平衡合奏由一个有效的量子哈密顿量，由纳米结构的哈密顿量和偏置算子。偏置算子，写在多体散射状态，体现了开放环境的非平衡边界条件。与时间无关的算符的期望值可以在不需要解析延拓的情况下计算，而远离平衡定态的量子模拟至今还很缺乏。PI方法能够确定稳态传输的基本特性，如I-V曲线。该算法有望连续覆盖从多体相干输运到单体输运的宽偏差范围。凭借量子蒙特卡罗算法的灵活性，PI计划将模拟扩展到多点和多级系统。系统地研究了位间共振、失相和电压降。 由非平衡边界条件引起的非局部效应以受控的方式包括在内。PI的通用算法可能对其他领域产生更广泛的影响，这些领域可能有助于未来的信息技术，包括：量子信息控制，自旋电子学，量子光学和量子计算。封闭系统（例如量子点）耦合到开放环境（例如，金属引线）构成了量子信息如何通过多体相互作用和与环境自由度的耦合来传输、去相位和减少的一般问题。这项关于量子非平衡系统的工作可能会对化学和核心电子工程产生进一步的影响。该奖项是根据信息技术研究招标NSF-04-012提交给材料研究部的提案而颁发的。该奖项涵盖的研究活动属于国家优先领域，“科学与工程的进步”和技术重点领域，“计算建模或模拟研究的创新”。“该奖项支持量子点和其他纳米结构中非平衡传输的基础计算和理论研究。 在强电场的影响下，量子点和纳米结构等材料中的电子是一个强烈相互作用的粒子系统，远离平衡，并提出了一个具有智力挑战性的基本问题。这种系统还没有得到很好的理解，但同时可以构成未来技术的基础。PI建议开发一种新的算法，他将使用该算法来研究相互作用之间的相互作用以及系统失去平衡的程度。除了算法的发展，算法的使用可能会影响未来的信息技术。

This award was made on a proposal submitted to the Division of Materials Research under the Information Technology Research solicitation NSF-04-012. Research activities covered by this award fall under the National Priority Area, "Advances in Science and Engineering," and the Technical Focus Area, "Innovation in Computational Modeling or Simulation in Research." This award supports fundamental computational and theoretical research on nonequilibrium transport in quantum dots and nanostructures. On the nanometer length scale, high-bias nonequilibrium and quantum many-body effects are intimately coupled and conventional theories for transport in semiconductor devices become inadequate. The PI will develop a quantum simulation algorithm for steady state nonequilibrium systems. Quantum Monte Carlo simulations will be used to sample steady-state nonequilibrium ensembles governed by an effective quantum Hamiltonian that consists of the nanostructure Hamiltonian and the bias operator. The bias operator, written in terms of many-body scattering states, embodies the nonequilibrium boundary conditions of an open environment. Expectation values of time-independent operators can be calculated without analytic continuation.Quantum simulation in the far-from-equilibrium steady state has been lacking to date. The PI's method enables the determination of essential characteristics of steady-state transport, such as I-V curves. The algorithm is expected to continuously cover wide bias regimes from many-body coherent transport to one-body transport. With the flexibility of the quantum Monte Carlo algorithm, the PI plans to extend simulations to multi-dot and multi-level systems. The inter-site resonance, dephasing and voltage-drop will be investigated systematically. Non-local effects induced by the nonequilibrium boundary condition are included in a controlled manner. The PI's general algorithm may have broader impact on other fields that may contribute to future information technology, including: quantum information control, spintronics, quantum optics, and quantum computation. A confined system (eg. quantum dots) coupled to an open environment (eg. Metallic leads) constitutes a general problem of how quantum information is transported, dephased and reduced by the many-body interactions and the coupling to the environmental degrees of freedom. This work on quantum nonequilibrium systems may have further impact on chemistry and core electrical engineering. %%%This award was made on a proposal submitted to the Division of Materials Research under the Information Technology Research solicitation NSF-04-012. Research activities covered by this award fall under the National Priority Area, "Advances in Science and Engineering," and the Technical Focus Area, "Innovation in Computational Modeling or Simulation in Research." This award supports fundamental computational and theoretical research on nonequilibrium transport in quantum dots and other nanostructures. Electrons in materials such as quantum dots and nanostructures under the influence of strong electric fields are a system of strongly interacting particles that is far from equilibrium and presents a fundamental problem that is intellectually challenging. Such systems are not well understood and at the same time can form the basis for future technologies. The PI proposes to develop a new algorithm that he will use to study the interplay between interactions and the degree to which a system is out of equilibrium. In addition to algorithmic development, the use of the algorithm may impact future information technology.***