Emulation is a technique that replaces costly simulators with much cheaper statistical models in Bayesian inference problems. We have developed DarkEmulator that predicts basic statistical quantities in the cosmological structure formation. This code is then applied to real data from Subaru Hyper Suprime-Cam as well as Sloan Digital Sky Survey. The combination of these two data sets, the former probes the weak gravitational lensing effect while the latter probes the three dimensional galaxy distribution on large scales, offers a unique opportunity to break the degeneracy between cosmology and galaxy physics. We report competitive bounds on the parameter S₈ , the amplitude of the cosmological fluctuations at present. This new methodology would serve as a realistic solution for simulation-based inference, which can reveal unexplored information on small scales where nonlinearity is significant.

We review recent progress on non-reciprocal phase transitions, a new class of non-equilibrium phase transition that cannot be described by an optimization principle.

The so-called “proton spin puzzle” has been a long standing question in the study of the strong interaction, QCD. In order to disentangle it, the different contributions to the proton spin from quark spins, gluon spins and their orbital angular momenta need to be extracted. We review how well these components have been experimentally obtained at present and its theoretical impact.

In recent years, technology around quantum computer sounds growing well. Here, as “users” of quantum computers, we discuss how we can apply this development to numerical simulations of quantum field theories. As quantum computer is suitable for Hamilton formalism rather than Lagrange formalism, we do not have infamous sign problem from the beginning in contrast to the conventional Monte Carlo approach. We show recent results on quantum simulations of the charge-q Schwinger model, which is 1+1-dimensional quantum electrodynamics coupled to an electron with electric charge q. It turns out that our approach enables us to explore interesting phenomena coming from non-small θ-term such as negative string tension behavior in potential between charged heavy particles.

Novel quasi-elastic scattering spectroscopy using time-domain interferometry (TDI) of Mössbauer gamma rays allows us to determine the intermediate scattering function in time scales between nanosecond and microsecond. We introduce the basic principle of the TDI-based quasi-elastic scattering technique. In addition, we introduce the following three application studies by using TDI; Johari-Goldstein process in supercooled liquids and microscopic origins of viscosities in higher alcohol and two-dimensional membrane systems, respectively. Finally, we describe the outlook of further development of related techniques.