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single superconducting articial atom and microwave photons in the deep strong coupling regime [7]. According to some theoretical studies, a similar ground state may not occur in the deep strong coupling regime for multiple ar-ticial atoms and photons. Hence in the future, we plan to verify this theory by increasing the number of articial atoms [10]. Also, to improve the quantum state control techniques for quantum communication node technology and to achieve better control of ground states in multi-body systems, we plan to continue with research aimed at im-proving the techniques for manipulating these entangled states and clarifying the dynamics of light absorption and emission.ReferenceR1S. Haroche and J.-M. Raimond, Exploring the Quantum, Oxford University Press 2006.2I. Chiorescu, P. Bertet, K. Semba, Y. Nakamura, C. J. P. M. Harmans, and J. E. Mooij, “Coherent dynamics of a flux qubit coupled to a harmonic oscilla-tor,” Nature vol.431, pp.159–162, 2004.3A. Wallraff, D. I. Schuster, A. Blais, L. Frunzio,R.- S. Huang, J. Majer, S. Kumar, S. M. Girvin, and R. J. Schoelkopf, “Strong coupling of a single photon to a superconducting qubit using circuit quantum electrodynamics,” Nature 431, pp.162–167, 2004.4K. Semba, S. Saito, K. Kakuyanagi, H. Nakano, “Experiment of Cavity Quantum Electrodynamics is Now Possible in a Superconducting Circuit! : Josephson Cavity-QED,” Butsuri 64(1), pp.37-41, 2009. (in Japanese)5T. Niemczyk, F. Deppe, H. Huebl, E. P. Menzel, F. Hocke, M. J. Schwarz, J. J. Garcia-Ripoll, D. Zueco, T. Hümmer, E. Solano, A. Marx, and R. Gross, “Circuit quantum electrodynamics in the ultrastrong-coupling regime,” Nature Physics, vol.6, pp.772–776, 2010.6P. Forn-Díaz, J. Lisenfeld, D. Marcos, J. J. García-Ripoll, E. Solano, C. J. P. M. Harmans, and J. E. Mooij, “Observation of the Bloch-Siegert Shift in a Qubit-Oscillator System in the Ultrastrong Coupling Regime,” Physical Review Letters, vol.105, no.23, pp.237001-1-4, 2010.7F. Yoshihara*, T. Fuse*, S. Ashhab, K. Kakuyanagi, S. Saito, and K. Semba, : “Superconducting qubit-oscillator circuit beyond the ultrastrong- coupling re-gime,” Nature Physics 13, 44, 2017. (* These authors contributed equally to this work.)8S. Saito, K. Kakuyanagi, S. Ashhab, F. Yoshihara, T. Fuse, and K. Semba, : “Discovery of a Stable Molecular State Consisting of Photons and an Artificial Atom,” NTT Technical Review vol.13, pp.44-47, 2017.9S. Ashhab and Franco Nori, “Qubit-oscillator systems in the ultrastrong-coupling regime and their potential for preparing nonclassical states,” Phys. Rev. A 81, 042311, 2010.10S. Ashhab and K. Semba, “Superradiance phase transition in the presence of parameter fluctuations,” Phys. Rev. A 95, 053833, 2017.Kouichi SEMBA, Dr. Eng.Executive Researcher, Frontier Research Laboratory, Advanced ICT Research InstituteSuperconducting quantum electronicsFumiki YOSHIHARA, Ph.DSenior Researcher, Frontier Research Laboratory, Advanced ICT Research InstituteSuperconducting quantum electronicsTomoko FUSE, Ph.DSenior Researcher, Frontier Research Laboratory, Advanced ICT Research InstituteSuperconducting quantum electronicsSahel ASHHAB, Ph.DSenior Scientist, Qatar Environment and Energy Research InstituteTheory, modeling, and simulationKosuke KAKUYANAGI, Ph.DSenior Research Scientist, Hybrid Nano-Structure Physics Research groupSuperconducting quantum physicsShiro SAITO, Dr. Eng.Senior Research Scientist, Hybrid Nano-Structure Physics Research groupSuperconducting quantum physics4 Quantum Node Technology70　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 1 (2017)