Nonlinear optical responses in noncentrosymmetric superconductors

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.Comment: 21 pages and 9 figure

Nonlinear optical responses in superconductors under magnetic fields: quantum geometry and topological superconductivity

Noncentrosymmetric superconductors offer fascinating phenomena of quantum transport and optics such as nonreciprocal and nonlinear responses. Time-reversal symmetry breaking often plays an essential role in the emergence and enhancement of nonreciprocal transport. In this paper, we show the nonreciprocal optical responses in noncentrosymmetric superconductors arising from time-reversal symmetry breaking by demonstrating them in $s$-wave superconductors with a Rashba spin-orbit coupling and a magnetic field. Numerical results reveal the superconductivity-induced bulk photocurrent and second harmonic generation, which are forbidden at the zero magnetic field. We discuss the properties and mechanisms of the superconducting nonlinear responses emerging under the magnetic field. In particular, we investigate the magnetic-field dependence of the photocurrent conductivity and clarify the essential ingredients which give a contribution unique to superconductors under the magnetic field. This contribution is dominant in the low carrier density regime although the corresponding joint density of states is tiny. We attribute the enhancement to the quantum geometry. Moreover, the nonlinear conductivity shows peculiar sign reversal at the transition to the topological superconducting state. We propose a bulk probe of topological transition and quantum geometry in superconductors.Comment: 36 pages, 21 figure

Physics Informed Machine Learningを用いた宇宙機熱解析と不確かさ低減

要約のみTohoku University永井大樹課

3D Particle Simulation of Liver Cell Proliferation with Angiogenesis - Partial Hepatic Lobule Formation-

Recently, the prevalence of viral hepatitis patients has been increasing. Therefore, the reconstruction of liver based on tissue engineering has attracted significant attention. However, the formation or regeneration mechanisms of the liver have not been elucidated; therefore, practical regenerative medicine technology based on tissue engineered liver has not been accomplished. In this study, we propose an analysis model using a Particle Model as the first step. The analysis object is a hepatic lobule. The purpose of this analysis is to elucidate the process of cell proliferation, mechanisms, and states at the micro scale. We used parameters which were obtained by experiments using rats relating to diffusivity, oxygen concentration, and oxygen consumption of a cell. Moreover, we used complex velocity potential of fluid dynamics and obtained a result corresponding to a real hepatic lobule, qualitatively.The 6th TSME International Conference on Mechanical Engineering, 16-18 December 2015, at The Regent Cha-am beach Resort, Hua-Hin, Thailand

An analysis of half elliptical surface crack propagation phenomenon with smoothed particle hydrodynamics method

The smoothed particle hydrodynamics (SPH) method was applied to the problem of fatigue crack propagation. The stress singularity characteristics at the crack tip and the stress intensity factor were compared between the SPH results and the reference values. The result of half elliptical surface crack propagation analysis showed smooth crack propagation history and the shape of the analyzed fracture surface was close to that achieved by test. Accordingly, it is concluded that the SPH is a useful tool to analyze the linear elastic fracture mechanics and the fatigue crack propagation

An analysis of three-dimensional non-planar crack propagation phenomenon with smoothed particle hydrodynamics method

In the present study, the non-planar crackpropagation problems in the 3D body are solved, extending our previous study on the smoothed particle hydrodynamics (SPH) method applied to the fatigue crack propagation of the planar cracks in the 3D body. To solve the propagation of the non-planar crack, the crack front particles are given the information of the slope and the position of the crack surface in addition to the crack length. To confirm the validity of the proposed method, a fatigue test of the CT specimen with an additional horizontal hole is carried out and the result is compared with the computed one successfully

<Reports on the Eighth Annual Meeting of the Tsukuba English Linguistic Society> Attitude Reports and Semantic Theories

We examined various semantic theories with respect to the treatment of attitude reports, such as believe, know, see/see that and hear/hear that. ..

2D Particle Simulation of Liver Cell Proliferation with Angiogenesis - Hepatic Lobule Formation

The liver has the ability to reform and regenerate in our body. However, the mechanisms of reformation or regeneration of the liver have not been elucidated. In this study, we propose an analysis model using a Particle Model to elucidate the mechanism of liver formation. The object of analysis is a hepatic lobule, which is the basic component of the liver. First, a 2-dimensional cell proliferation around one blood vessel was modeled. Second, angiogenesis was added and considered. And finally, the model was applied to the hepatic lobule and the 2D formation of the hepatic lobule was revealed. We used experimentally derived parameters such as diffusivity, oxygen concentration, and oxygen consumption of a cell. The model will be expected to facilitate in developing tissue-engineered liver using regenerative medicine technology.2nd Conference on Advances in Prevention and Treatment of Cancer (CAPTC 2016), March 18-20, 2016, Los Angeles, US

3D Particle Simulation of Liver Cell Proliferation with Angiogenesis - Partial Hepatic Lobule Formation-

The 6th TSME International Conference on Mechanical Engineering, 16-18 December 2015, at The Regent Cha-am beach Resort, Hua-Hin, Thailand.Recently, the prevalence of viral hepatitis patients has been increasing. Therefore, the reconstruction of liver based on tissue engineering has attracted significant attention. However, the formation or regeneration mechanisms of the liver have not been elucidated; therefore, practical regenerative medicine technology based on tissue engineered liver has not been accomplished. In this study, we propose an analysis model using a Particle Model as the first step. The analysis object is a hepatic lobule. The purpose of this analysis is to elucidate the process of cell proliferation, mechanisms, and states at the micro scale. We used parameters which were obtained by experiments using rats relating to diffusivity, oxygen concentration, and oxygen consumption of a cell. Moreover, we used complex velocity potential of fluid dynamics and obtained a result corresponding to a real hepatic lobule, qualitatively