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

ITR：稳态非平衡量子多体输运模拟算法研究进展

• 批准号: 0426826
• 负责人: Jong Han
• 金额: $ 58.5万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2009-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0426826&HistoricalAwards=false
• 关键词: ITR; Advances; Simulation; Algorithm; Quantum

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.***

该奖项是根据在信息技术研究征集NSF-04-012项下提交给材料研究部的一份提案而颁发的。该奖项所涵盖的研究活动属于国家重点领域“科学与工程进展”和技术重点领域“计算建模或研究中的模拟创新”。该奖项支持量子点和纳米结构中非平衡输运的基础计算和理论研究。在纳米尺度上，高偏压非平衡效应和量子多体效应紧密耦合，传统的半导体器件输运理论不再适用。PI将开发一种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由有效的量子哈密顿量控制的稳态非平衡系综，该有效量子哈密顿量由纳米结构哈密顿量和偏置算符组成。用多体散射态表示的偏心算符体现了开放环境中的非平衡边界条件。时间无关算符的期望值可以在没有解析连续的情况下计算，但在远离平衡的稳态下的量子模拟到目前为止还很缺乏。PI方法能够确定稳态输运的基本特性，例如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各种偏置区域。利用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能级系统。对场内谐振、移相和压降进行了系统研究。由非平衡边界条件引起的非局部效应以受控的方式被包括在内。PI的通用算法可能会对其他可能有助于未来信息技术的领域产生更广泛的影响，包括：量子信息控制、自旋电子学、量子光学和量子计算。受限的系统(例如。量子点)耦合到开放环境(例如。金属铅)构成了一个普遍的问题，即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、去相和还原。这项关于量子非平衡系统的工作可能会对化学和堆芯电气工程产生进一步的影响。该奖项是根据信息技术研究征集NSF-04-012项下提交给材料研究部的一份建议书颁发的。该奖项所涵盖的研究活动属于国家重点领域“科学与工程进展”和技术重点领域“计算建模或研究中的模拟创新”。该奖项支持有关量子点和其他纳米结构中非平衡输运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相互作用粒子系统，远离平衡，提出了一个在智力上具有挑战性的基本问题。这样的系统没有得到很好的理解，同时也可能成为未来技术的基础。PI提议开发一种新的算法，他将使用该算法来研究相互作用和系统失衡程度之间的相互作用。除了算法开发之外，算法的使用可能会影响未来的信息技术。*