Multicomponent superconductors are platforms of exotic pairing symmetry and topological superconductivity. Multiple superconducting phases observed in a heavy fermion compound CeRh₂As₂ [1] are discussed based on theory of locally noncentrosymmetric superconductors [2]. Topological superconductivity is proposed by combining density functional theory and ARPES experiment [3,4]. I will also show the vortex phase diagram, which indicates a fractional vortex phase identified as a topological meron state [5]. Based on the peculiar band structure predicted by first-principles calculations, we construct a periodic Dirac-Anderson model and demonstrate odd-parity superconducting phase arising from interplay of quantum geometry and electron correlation [6].

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[2] T. Yoshida, M. Sigrist, and Y. Yanase, Phys. Rev. B 86, 134514 (2012).

[3] J. Ishizuka, K. Nogaki, M. Sigrist, Y. Yanase, Phys. Rev. B 110, L140505 (2024).

[4] Xuezhi Chen, Le Wang, Jun Ishizuka, Kosuke Nogaki, Yiwei Cheng, Fazhi Yang, Renjie Zhang, Zhenhua Chen, Fangyuan Zhu, Youichi Yanase, Baiqing Lv, Yaobo Huang, Phys. Rev. X 14, 021048 (2024).

[5] Akihiro Minamide, Youichi Yanase, Phys. Rev. Lett. 134, 026002 (2025).

[6] Kosuke Nogaki and Youichi Yanase, arXiv:2510.24289.