Superconductivity due to a repulsive interaction

项目描述：标准BCS理论指出1型超导的起源是通过声子引起的吸引力相互作用。2型超导体或高温超导体的起源仍然未知。U =无穷大的哈伯德模型（描述许多2型超导体）将被求解，产生超导解。这将显示使用精确对角化和分析使用平均场理论和杂质理论的数值。一旦这一点被证明，使用微扰理论将解除U =无穷大的限制，以显示超导性的加强。

Project Description: Standard BCS theory states the origin of Type 1 superconductivity is through an attractive interaction due to phonons. The origin of Type 2 superconductivity, or high temperature superconductors, is still unknown. A Hubbard model (which describes many Type 2 superconductors) with U = infinity will be solved, producing a superconducting solution. This will be shown numerically using exact diagonalization and analytically using mean field theory and impurity theory. Once this is shown the limit U = infinity will be lifted using perturbation theory to show the superconductivity strengthen.