Correlation effects in quantum dots and wires

量子点和量子线的相关效应

• 批准号: 35776612
• 负责人: Professor Dr. Volker Meden
• 金额: --
• 依托单位: Institut für Festkörperphysik
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/35776612?language=en
• 关键词: Correlation; effects; quantum; dots; wires

In this project we investigate correlation effects in (quasi) one-dimensional quantum wires and in “zero”-dimensional quantum dots with a particular focus on the transport properties of such systems in the linear response regime and singleparticle spectral properties. We have successfully applied a truncation scheme leading to a static self-energy to problems of direct experimental relevance (“phase lapse puzzle” and charging of multi-level dots, Josephson current through correlated quantum dot). The static approximation can only be used in situation in which inelastic processes are irrelevant (e.g. temperatur T = 0 conductance). We thus extended the truncation scheme and kept the frequency dependence of the two-particle vertex which within the one-particle irreducible functional RG leads to a frequency dependent self-energy. We applied this scheme to study the singleimpurity Anderson model (in the appropriate parameter regime dominated by spin fluctuations) and the interacting resonant level model (dominated by charge fluctuations). We discussed the merits and drawbacks of this scheme. We will try to improve on the latter (higher-order corrections). Next we will use the frequency dependent approximation to investigate more complex systems of quantum dots showing a physics which is dominated by the interplay of the Kondo effect and other interactions (such as the RKKY). We will extend the frequency dependent scheme to study quantum wires. An interesting question is the crossover between bulk and boundary Luttinger liquid physics. Finally, we will use the frequency dependent scheme to study fermionic systems coupled to bosons (e.g. local electronic levels coupled to phonons.)

在这个项目中，我们研究了(准)一维量子线和“零”维量子点中的关联效应，特别关注了这类系统在线性响应区的输运性质和单粒子光谱性质。我们已经成功地将导致静态自能的截断方案应用于直接实验相关的问题(“相移之谜”、多能级点的充电、约瑟夫森电流通过关联量子点)。静态近似只能在非弹性过程不相关的情况下使用(例如温度T=0电导)。因此，我们扩展了截断方案，并保持了两粒子顶点的频率依赖性，在单粒子不可约泛函RG中，这导致了频率相关的自能。我们应用该方案研究了单杂质Anderson模型(在合适的参数范围内以自旋涨落为主)和相互作用共振能级模型(以电荷涨落为主)。我们讨论了这个方案的优点和缺点。我们将努力改进后者(高阶修正)。接下来，我们将使用频率相关近似来研究更复杂的量子点系统，显示出由近藤效应和其他相互作用(如RKKY)相互作用主导的物理。我们将把频率依赖方案推广到研究量子线。一个有趣的问题是整体和边界勒廷格液体物理之间的交叉。最后，我们将使用频率相关方案来研究与玻色子耦合的费米子系统(例如，与声子耦合的局域电子能级)。