特集「量子力学の世紀」

はじめに

This article discusses the significance of the year 1925 in the history of quantum physics and explores perspectives on the historiography of quantum physics from a longer term viewpoint.

Three-nucleon systems are essential to investigate three-nucleon forces (3NFs) that act in more than two nucleon systems. Rigorous numerical calculations in terms of the Faddeev theory and precise measurements for deuteron-proton elastic scattering have provided clear evidence of the 3NF effects. More recently, the significance of the 3NFs has been extended to describe a wide range of nuclear phenomena, from a few to infinite nucleon systems.

Superfluidity and superconductivity are remarkable phenomena stemming purely from quantum mechanical effects. Numerous particles that comprise systems maintain coherence over a macroscopic scale and behave as a huge quantum mechanical wave. The enigmatic phenomena of quantum mechanics are amplified on a macroscopic scale, allowing for direct observation and manipulation. Here we introduce macroscopic quantum phenomena in superfluids and superconductors, focusing on quantum vortices and the Josephson effect.

Ultrafast phenomena constitute a subfield of condensed matter photo-physics, focusing on elucidating and controlling events that occur within timescales ranging from attoseconds (10^-18 s) and femtoseconds (10^-15 s) to picoseconds (10^-12 s) and nanoseconds (10^-9 s). A defining characteristic of this field is the direct observation of phenomena on the very timescale in which light-matter interactions take place, allowing for an in-depth exploration of the underlying physics. Furthermore, research in this field aims to achieve ultrafast control of various material properties, which contributes to the fundamental understanding of optical devices and solar cells and chemical reaction control. This paper provides an overview of how the study of ultrafast phenomena has evolved within the framework of quantum mechanics and condensed matter photo-physics, both of which were established roughly a century ago, and offers insights into future perspectives from the author’s viewpoint. It is my hope to convey the fascinating and dynamic physics that emerge from light-matter interactions.

Some people may be hearing the term “nanomechanics” for the first time. “Nano” means one billionth of a size, so you can think of it as “extremely small.” “Mechanics” can be broadly interpreted as dealing with mechanical elements, but here it is used to mean “something that uses vibration” and refers to research on elements that resonate at specific frequencies, called “mechanical resonators.” This article outlines the trends and future prospects of the “nanomechanics” research field, which has developed to this day in close relation to quantum mechanics.

We review recent developments on relativistic chiral matter that is expected to appear in various systems, such as electroweak plasma in the early universe, quark-gluon plasmas created in heavy ion collisions, neutrino matter in core-collapse supernovae, and topological matter called Weyl semimetals.

In this article, we present current status of lattice simulation results in cold and dense two-color QCD medium, particularly provided by our Japanese group. We also report some results based on the linear sigma model motivated by those numerical experiments.