Physics of Low Dimensional Electron Systems

在本研究计划中，我们研究了电子关联对低维电子系统的影响，并应用所得结果解释了一些实验结果。特别地，我们使用了精确解和共形场论（CFT）方法。我们简要总结了所获得的结果。(1)具有梯形结构的电子系统：为了理解氧化物Sr_<n-1>Cu_（n+1）O_<2n>的特征性质，我们用玻色化技术研究了耦合Hubbard链。(2)杂质系统的临界性质：利用Kondo效应的精确解和连续傅里叶变换，研究了杂质系统的临界行为。发现了表征费米液体和正交突变的两种临界指数。(3)一维电子系统的多带效应：利用精确解和CFT方法研究了具有两带结构的一维超对称t-J模型，阐明了Mott绝缘体的两带效应。(4)排斥统计中的输运系数：我们已经计算了服从排斥统计的多粒子系统的输运系数。我们得到了统计相互作用与输运系数的关系。(5)量子线中的电导涨落：研究了介观量子线中的电导涨落。在强局域区，电导涨落可以用共振隧穿来解释。

In this research project, we have studied the effect of electron correlations on low-dimensional electron systems, and have applied the obtained results to explain some experimental findings. In particular, we have used the methods of exact solution and conformal field theory (CFT). We briefly summarize the obtained results.(1) Electron systems with ladder structure :In order to understand characteristic properties of the oxide compounds Sr_<n-1>Cu_<n+1>O_<2n>, we have studied the coupled Hubbard chain by means of bosonization techniques.(2) Critical properties of impurity systems :By using the exact solution of the Kondo effect and CFT,we have studied the critical behavior of impurity systems. Two kinds of critical exponents have been found, which characterize the Fermi liquid and the orthogonality catastrophe.(3) Multi-band effects on 1D electron systems :The one-dimensional supersymmetric t-J model with two-band structure has been studied by using the exact solution and CFT.The two-band effect on the Mott insulator has been clarified.(4) Transport coefficients in exclusion statistics :We have calculated transport coefficients for many-particle systems obeying exclusion statistics. We have obtained the relation of the statistical interaction to transport coefficients.(5) Conductance fluctuations in quantum wires :The conductance fluctuations in mesoscopic quantum wires have been investigated. In the strongly localized regime, the conductance fluctuation can be explained by resonance tunneling.