The large-charge expansion, a novel method of solving strongly-coupled conformal field theories (CFTs) is introduced. We review the method using a pedagogical example of the O(2) Wilson-Fisher CFT in three dimensions, by computing the operator dimension of ϕ^Q at large-Q. We also comment on the comparison of the analytic result with numerical data using the Monte-Carlo simulation.

Nanomaterial hybrid structures are intensively investigated to generate novel properties: atomic layer materials acquire twistronic properties through bilayer structures, and semiconductor quantum dots (QDs) also acquire cooperative properties by forming QD superlattices. In the QD superstructures, excitons of aligned QDs cooperatively interact with each other. We found that nonlinear coherent responses of multiexcitons are enhanced by the quantum cooperative effects in QD superstructures. Furthermore, we clarified that the cooperative effect is tunable by controlling the inter-QD distance. Since the nonlinear coherent responses are detectable by photocurrent, the cooperative enhancement processes will lead to boosting applications in advanced optoelectronics.

A prototype of the quantum anomalous Hall resistance standard with a permanent magnet was developed. High-precision measurements demonstrated the quantization of Hall resistance to the von Klitzing constant within 10-parts-per-billion accuracy. This demonstration established an important milestone for the development of a quantum resistance standard without a superconducting electromagnet.

Inspired by the recent development in quantum computers, much efforts have been devoted to exploring the potential applications in lattice gauge theories. To this end, we need to construct lattice gauge theories based on the Hamiltonian formalism. We present the Hamiltonian formalism of the Yang–Mills theory and a numerical example simulating thermalization using classical computers.