Many-Body Effect and Cooperative Phenomena in High-Density Exciton Systems Driven by Light

光驱动高密度激子系统中的多体效应和协同现象

• 批准号: 11215206
• 负责人: AIHARA Masaki
• 金额: $ 10.94万
• 依托单位: NARA INSTITUTE OF SCIENCE AND TECHNOLOGY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research on Priority Areas (B)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2001
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11215206/
• 关键词: Exciton; Bose-Einstein condensation; Macroscopic quantum state; Electron correlation; Superconductivity; BCS state; Eliashberg方程式; 非線形光学; コヒーレンス; シュレディンガー方程式

We have presented for the first time the unified theory of luminescence spectra for highly excited electron-hole systems which is applicable both to the electron-hole BCS state and to the exciton BEC state. The multiple Coulomb interaction between electron-hole pairs is taken into account by numerically solving the Bethe-Salpeter equation for electron-hole pair correlation function. The effect of the collective quantum fluctuation associtated with the center-of-mass motion of electron-hole pairs is incorporated by the generalized random-phase approximation. The crossover from the exciton BEC to the electron-hole BCS state clearly manifests itself in the calculated luminescence spectra.We have also investigated photo-generated states in strongly correlated electron systems. We have derived the effective Hamiltonian of the Hubbard model for the multi-photon excited states assuming sufficiently large on-site repulsive Coulomb interaction. We have calculated two-photon excited states for a system with 20 sites in the half-filled case with exactly diagonalizing the effective Hamiltonian. We have found that the correlation function for the d-wave superconductivity has finite values even for large distance. This strongly suggests that the photo-induced superconductivity arises in strongly correlated electron systems.

本文首次提出了高激发态电子-空穴体系发光光谱的统一理论，它既适用于电子-空穴BCS态，也适用于激子BEC态。通过数值求解电子-空穴对关联函数的Bethe-Salpeter方程，考虑了电子-空穴对之间的多重库仑相互作用。在广义无规相位近似下，考虑了与电子-空穴对质心运动有关的集体量子涨落效应。从激子BEC到电子-空穴BCS态的跃迁在计算的发光光谱中清晰地表现出来。我们还研究了强关联电子系统中的光生态。在充分大的在位排斥库仑相互作用下，导出了多光子激发态Hubbard模型的有效哈密顿量。在半满情况下，我们计算了20个格点系统的双光子激发态。我们发现d波超导的关联函数即使在大距离下也有有限值。这有力地表明，光致超导性出现在强关联电子系统。

项目成果

T.J.Inagaki and M.Aihara: "Propagation properties of exciton polaritons in highly excited semiconductors"International Journal of Modern Physics B. (掲載許可). (2001)

T.J.Inagaki 和 M.Aihara：“高激发半导体中激子极化激元的传播特性”国际现代物理学杂志 B.（出版许可）。

A. Takahashi, S. Yoshikawa and M. Aihara: "Multi-photon excited states of two-dimensional strongly correlated electron systems"Physical Review B. (in press).

A. Takahashi、S. Yoshikawa 和 M. Aihara：“二维强相关电子系统的多光子激发态”物理评论 B.（出版中）。

T.J.Inagaki, M.Aihara: "Propagation properties of high-density exciton polaritons"Excitonic Processes in Condensed Matter(edited by K. Cho and A. Matsui, World Scientific). 453-456 (2001)

T.J.Inagaki、M.Aihara：“高密度激子极化激元的传播特性”凝聚态物质中的激子过程（K. Cho 和 A. Matsui 编辑，World Scientific）。

T.J.Inagaki,T.Iida,and M.Aihara: "Many-body theory of pump-probe spectra for highly excited semiconductors"Physical Review B. 62・16. 10852-10860 (2000)

T.J.Inagaki、T.Iida、M.Aihara：“高激发半导体的泵浦探针光谱的多体理论”物理评论 B. 62・16（2000）。

T.J Inagaki and M.Aihara: "Nonlinear optical response by spatially separated light beams in a condensed exciton system"Journal of Luminescnece. (in press). (2000)

T.J Inagaki 和 M.Aihara：“凝聚激子系统中空间分离光束的非线性光学响应”《Luminescnece》杂志。