Prof. Masahiro Katoh
Hiroshima Synchrotron Radiation Center, Hiroshima University
Institute for Molecular Science, National Institutes of Natural Sciences
Spatial Structure of Radiation from Relativistic Electrons
Electromagnetic radiations from relativistic electrons shows characteristic spatial structures on intensity, polarization, spectrum and phase. Electrons in helical motion radiate optical vortices which have helical wavefront and annular intensity distribution. This was experimentally verified by a diffraction and interference experiments on synchrotron light sources. Theoretically, it was shown that electrons in circular or helical motion generally radiate electromagnetic wave possessing helical phase structure and carrying orbital angular momentum. This radiation mechanism can be the basis of vortex radiation sources in the entire wavelength range, from radiowaves to gamma-rays. Moreover, by coherently superposing two optical vortices from electrons, structured light of other kinds such as optcal vector beam can be generated. On the other hand, electrons in helical motion exist widely in nature, particularly in the astrophysicsl environments. Optical vortices may play some important roles in natural sciences.
Masahiro Katoh received the B.E. degree from Tohoku University, Japan in 1981, M.E. degree from University of Tokyo in 1983, and Dr. Sci. degrees from Tohoku University, Japan, in 1997, respectively. He became a Research Associate at National Laboratory for High Energy Physics (KEK) in 1986, an Associate Professor and a Professor at Institute for Molecular Science in 2000, and in 2004, a Professor at Hiroshima University in 2019, respectively. He is currently a Professor in Hiroshima Synchrotron Radiation Center, Hiroshima University and a Project Professor in UVSOR Synchrotron, Institute for Molecular Science. His current research interests include beam physics in synchrotron light sources and electromagnetic radiation from relativistic electrons.
Prof. Satoshi Tanaka
Department of Physical Science, Osaka Prefecture University, Japan
Parametric amplification of quantum vacuum fluctuation with dissipation in terms of complex spectral analysis of Floquet-Liouvillian
Parametric amplification of a squeezed vacuum generalized from optomechanical cavity is theoretically studied in terms of complex spectral analysis of a Floquet-Liouvillian. The non-Hermitian effective Liouvillian is derived using the projection method. The competition between the parametric amplification and the dissipation loss is well described in a unified manner. We found a new type of the squeezed vacuum state between the different intracavity mode and the photonic band when the intracavity mode frequency is close to the band edge.
Satoshi Tanaka received the B.E., M.E., and Dr. Sci. degrees from Tohoku University, Japan, in 1983, 1985 and 1991, respectively. He became a Research Associate, an Associate Professor, and a Professor at Osaka Prefecture University in 1991, 1997, and 2006, respectively. He is currently a Professor in the Department of Physical Science, the Graduate School of Science, Osaka Prefecture University. His current research interests include quantum optics, quantum mechanics, and non-equilibrium statistical mechanics.
Mr. Yuki Goto
Department of Applied Energy, Nagoya University
Electron Cyclotron Emission with a Helical Wavefront in the Cyclotron Auto-resonance Acceleration
In this paper, we calculated the radiation from the state where electrons in cyclotron motion under the uniform magnetic field Bex were accelerated by the externally applied circularly polarized resonant wave with strong Ein and Bin. The coherent radiation with helical wavefront could be obtained in this system. The electrons were accelerated in the parallel direction by the term β × Bin as well as in the acceleration direction by the electric field of the wave Ein when the circularly polarized wave is injected from the outside. The radiation from such accelerated electrons is confirmed to have helical wavefront at harmonics cyclotron frequency.
Yuki Goto is a current Ph.D student in the Department of Applied Energy, the Graduate School of Engineering, Nagoya University. His current research interests include electron cyclotron emission with helical wavefront.