论文标题
非中心对称超导体中的非线性光学响应
Nonlinear optical responses in noncentrosymmetric superconductors
论文作者
论文摘要
源自库珀对的量子凝结，超导体的独特的非转录反应引起了人们的注意。最近，基于Bogoliubov-DE Gennes理论制定了非中心对称超导体中二阶非线性反应的理论。在本文中，我们研究了时间反转对称超导体的二阶光学响应的机制和条件。数值结果显示了超导状态下的特征光电流和第二个谐波产生。然而，在某些条件下，超导性诱导的非线性光学响应消失了。我们表明，对于二阶超导光响应，内标和带配对的共存是必需的。此外，与超导状态下浆果曲率的成分有关的超导浆果曲率因子对于非线性响应至关重要。因此，我们得出了出现超导非线性反应的微观条件。
The unique nonreciprocal responses of superconductors, which stem from the Cooper pairs' quantum condensation, have been attracting attention. Recently, theories of the second-order nonlinear response in noncentrosymmetric superconductors were formulated based on the Bogoliubov-de Gennes theory. In this paper, we study the mechanism and condition for second-order optical responses of time-reversal symmetric superconductors. The numerical results show the characteristic photocurrent and second harmonic generation in the superconducting state. However, the superconductivity-induced nonlinear optical responses disappear under some conditions on pair potential. We show that the coexistence of intraband and interband pairing is necessary for the second-order superconducting optical responses. In addition, the superconducting Berry curvature factor, which is related to a component of Berry curvature in the superconducting state, is essential for the nonlinear responses. Thus, we derived the microscopic conditions where the superconducting nonlinear response appears.
