Progress in the fabrication of ultra-low loss, highly nonlinear, and dispersion-engineered nanophotonics indicates the experimental capabilities are rapidly approaching the unprecedented regime of attojoule-per-pulse nonlinear optics. From the viewpoint of quantum optics, such strong nonlinearity suggest the potential to induce significant non-Gaussian quantum features, heralding a unique opportunity for all-optical quantum engineering and information processing using coherent dynamics of pulse propagation, e.g., soliton-based cubic phase gate. To understand and fully leverage the potential of broadband non-Gaussian quantum optics, however, it is essential to overcome the inherent challenges of modeling multimode non-Gaussian quantum states, which naïvely requires exponentially large Hilbert space. In this talk, we present recent developments of model reduction techniques to realize tractable numerical studies of non-Gaussian quantum pulse propagation, highlighting the physical insights that the reduced models provide. As constituent examples, we study Kerr soliton and pulsed squeezing, showing the emergence of physics beyond conventional Gaussian quantum optics, e.g., Wigner function negativities in the phase space.
 R. Yanagimoto, E. Ng et al., “Onset of non-Gaussian quantum physics in pulsed squeezing with mesoscopic fields”, arXiv:2111.13799.
 R. Yanagimoto et al., “Efficient simulation of ultrafast quantum nonlinear optics with matrix product states”, Optica 8, 1306 (2021).
 R. Yanagimoto, T. Onodera et al., “Engineering a Kerr-Based Deterministic Cubic Phase Gate via Gaussian Operations”, Phys. Rev. Lett. 124, 240503 (2020).
Ryotatsu Yanagimoto is a senior Ph.D. student in the group of Prof. Hideo Mabuchi at Stanford University. His research interest spans AMO physics in general, while he focuses on the science of quantum devices at present. He currently works on the theoretical research of broadband non-Gaussian quantum optics, aiming at understanding and engineering coherent multimode dynamics of photons on nonlinear nanophotonics beyond the conventional framework of Gaussian quantum optics. Previously, he worked at the University of Tokyo and RIKEN on experimental research of optical lattice clocks, where he received a B.E. He is a recipient of a Masason fellowship and a Stanford Q-FARM Ph.D. fellowship.