March 10 (Thu) at 13:30 - 15:00, 2022 (JST)
  • Yuto Ashida (Associate Professor, Graduate School of Science, The University of Tokyo)
  • via Zoom

Strong coupling between matter and quantized electromagnetic modes in cavity or waveguide may offer yet another approach of controlling equilibrium phases or dynamics of many-body systems. Recent developments have realized such strong light-matter interaction in genuinely quantum and nonperturbative regimes, where conventional approximate theoretical methods cannot be applied in general. I will talk about how one can analyze strongly coupled quantum light-matter systems at arbitrary interaction strengths on the basis of an asymptotically disentangling unitary transformation [1,2]. I discuss its application to construction of tight-binding Hamiltonians, dynamics of bound states in the continuum, and revisiting dissipative quantum phase transition in resistively shunted Josephson junctions [3].

*If you would like to participate, please contact Hidetoshi Taya.


  1. Y. Ashida, A. Imamoglu and E. Demler, Cavity Quantum Electrodynamics at Arbitrary Light-Matter Coupling Strengths, Phys. Rev. Lett (2021), doi: 10.1103/PhysRevLett.126.153603
  2. Yuto Ashida, Takeru Yokota, Atac Imamoglu, Eugene Demler, Nonperturbative Waveguide Quantum Electrodynamics, arXiv: 2105.08833
  3. K. Masuki, H. Sudo, M. Oshikawa and Y. Ashida, Absence versus Presence of Dissipative Quantum Phase Transition in Josephson Junctions, arXiv: 2111.13710