The momentum-resolved band structure provides fundamental information to understand the electronic properties of materials. The angle-resolved photoemission spectroscopy (ARPES) is a powerful technique to visualize the band structure by mapping the intensities of photoelectrons as a function of angle and energy. With the spin-resolved technique, we can also identify the spin-polarized character of the band. In addition, the time-resolved ARPES realized with a pump-probe technique can track the reordering process of electron system from its nonequilibrium state. In our laboratory, we utilize these various ARPES techniques and study the following phenomena: nonconventional superconductors, heavy fermions, strongly correlated systems, topological quantum phases, and quantum well states. Furthermore, we develop a new ARPES machine capable of achieving both the lowest measurement temperature and the highest energy resolution in the world by innovating a ^{3}He cryostat and a laser source. The state-of-art equipment will enable us to identify even a subtle electronic feature close to the Fermi level, such as an energy gap and a mode-coupled dispersion, which is typically tied to exotic behaviors of conduction electrons.

(a) Crystal structure of Bi_{2}Sr_{2}CuO_{6+d} high-T_{c} superconductor. (b) ARPES analyzer. (c) Diagram of ARPES experiment. (d) Snapshot of dispersion image. (e) Whole band structure. (f) Competition between superconducting gap and pseudogap. (g) Spectra around Fermi surface below (red) and above (black) superconducting transition temperature (T_{c }= 35 K). (h) Difference between the curves in (g). (h) Coherent spectral weight is painted with a red color, which is corresponding to the red region represented in (f).

^{*}Direct mapping of spin and orbital entangled wave functions under interband spin-orbit coupling of giant Rashba spin-split surface states: R. Noguchi, K. Kuroda, K. Yaji, K. Kobayashi, M. Sakano, A. Harasawa, T. Kondo, F. Komori and S. Shin, Phys. Rev. B95 (2017) 041111(R) (1-6).

Ultrafast energy- and momentum-resolved surface Dirac photocurrents in the topological insulator Sb_{2}Te_{3}: K. Kuroda, J. Reimann, K. A. Kokh, O. E. Tereshchenko, A. Kimura, J. Güdde and U. Höfer, Phys. Rev. B95 (2017) 081103(R).

^{*}Spin-dependent quantum interference in photoemission process from spin-orbit coupled states: K. Yaji, K. Kuroda, S. Toyohisa, A. Harasawa, Y. Ishida, S. Watanabe, C. Chen, K. Kobayashi, F. Komori and S. Shin, Nat. Commun.8 (2017) 14588 (1-6).

^{*}Coherent control over three-dimensional spin polarization for the spin-orbit coupled surface state of Bi_{2}Se_{3}: K. Kuroda, K. Yaji, M. Nakayama, A. Harasawa, Y. Ishida, S. Watanabe, C. -T. Chen, T. Kondo, F. Komori and S. Shin, Phys. Rev. B94 (2016) 165162(R) (1-5).

^{†*}Fermi arc electronic structure and Chern numbers in the type-II Weyl semimetal candidate Mo_{x}W_{1−x}Te_{2}: I. Belopolski, S. Y. Xu, Y. Ishida, X. Pan, P. Yu, D. S. Sanchez, H. Zheng, M. Neupane, N. Alidoust, G. Chang, T. R. Chang, Y. Wu, G. Bian, S. M. Huang, C. C. Lee, D. Mou, L. Huang, Y. Song, B. Wang, G. Wang, Y. W. Yeh, N. Yao, J. E. Rault, P. L. F`evre, F. Bertran, H. T. Jeng, T. Kondo, A. Kaminski, H. Lin, Z. Liu, F. Song, S. Shin and M. Z. Hasan, Phys. Rev. B94 (2016) 085127 (1-7).