"Physics of quantum-to-classical crossover and coherent Ising machines"
Speaker: Dr. Yoshihisa Yamamoto
Yoshihisa Yamamoto received his B.S. degree from Tokyo Institute of Technology and his M.S. and Ph. D. degrees from the University of Tokyo in 1973, 1975 and 1978, respectively. He joined NTT Basic Research Laboratories in 1978. He became a Professor of Applied Physics and Electrical Engineering at Stanford University in 1992. From 2003, he concurrently served as a Professor at National Institute of Informatics. Since 2014, he has been a Program Manager for Impulsive Paradigm Change through Disruptive Technologies Program (ImPACT) of Council for Science, Technology and Innovation, Cabinet Office, Government of Japan. He is currently a Professor (emeritus) at Stanford University and National Institute of Informatics, and NTT R&D Fellow. His research interest has been in coherent communication, quantum optics and quantum information processing.
In this talk, we will discuss the three quantum computation models, unitary quantum computation (UQC) [1,2], adiabatic quantum computation (AQC) [3,4] and dissipative quantum computation (DQC) [5,6]. The UQC is expected to solve efficiently problems with hidden periodicity such as factoring and discrete logarithm, while the AQC and DQC are expected to solve efficiently problems without any hidden period nor specific structure, such as combinatorial optimization problems. A coherent Ising machine (CIM) is a novel computing architecture based on the network of degenerate optical parametric oscillators and implements the DQC model [7,8]. The developed CIM has 2048 spins with all-to-all connections and is now available as a cloud system via internt . We will present the basic concept , operational principle  and benchmark study against modern algorithms  of the CIM.
 D. Deutsch, Proc. of the Royal Society of London. Series A, Mathematical and Physical Sciences, 400, 97–117 (1985); D. Deutsch and R. Jozsa, Proc. Roy. Soc. (London) A 439, 553 (1992).
 P. W. Shor, Proc. of the 35th Annual Symposium on Foundations of Computer Science, IEEE Computer Society Press,124 (1994).
 E. Farhi, J. Goldstone, S. Gutmann, J. Lapan, A. Lundgren, and D. Preda, Science 292, 472 (2001).
 T. Kadowaki and H. Nishimori, Phys. Rev. E 58, 5355 (1998).
 W. H. Zurek, Rev. Mod. Phys. 75, 715 (2003).
 F. Verstraete, M. M. Wolf, and J. I. Cirac, Nature Phys. 5, 633 (2009).
 A. Marandi Z. Wang, K. Takata, R. L. Byer, and Y. Yamamoto, Nature Photonics 8, 937 (2014); T. Inagaki, K. Inaba, R. Hamerly, K. Inoue, Y. Yamamoto, and H. Takesue, Nature Photonics 10, 415 (2016).
 T. Inagaki, Y. Haribara, K. Igarashi, T. Sonobe, S. Tamate, T. Honjo, A. Marandi, P. L. McMahon, T. Umeki, K. Enbutsu, O. Tadanaga, H. Takenouchi, K. Aihara, K. Kawarabayashi, K. Inoue, S. Utsunomiya, and H. Takesue, Science 354, 603 (2016); P. L. McMahon, A. Marandi, Y. Haribara, R. Hamerly, C. Langrock, S. Tamate, T. Inagaki, H. Takesue, S. Utsunomiya, K. Aihara, R. L. Byer, M. M. Fejer, H. Mabuchi, and Y. Yamamoto, Science 354, 614 (2016).
 S. Utsunomiya, K. Takata, and Y. Yamamoto, Opt. Express 19, 18091 (2011).
 Z. Wang, A. Marandi, K. Wen, R. L. Byer, and Y. Yamamoto, Phys. Rev. A 88, 063853 (2013); T. Leleu, Y. Yamamoto, S. Utsunomiya, and K. Aihara, Phys. Rev. E 95, 022118 (2017).
 Y. Haribara, H. Ishikawa, S. Utsunomiya, K. Aihara, and Y. Yamamoto, Quantum Sci. Tech. 2, 044002 (2017).
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