X-ray Compton scattering is a powerful technique to measure the electron momentum distribution in the full Brillouin zone and thus the full shape of the Fermi surface. Here, we review a historical overview about Compton scattering, explain why it detects the electron momentum distribution, provide several examples of Fermi surface measurements, make a comparison with other techniques such as quantum oscillation and angle-resolved photoemission spectroscopy, and introduce a recent progress to reveal the shape of the Fermi surface in high-temperature cuprate superconductors and also other progresses.

Core-collapse supernova (CCSN) explosion is a fiery death of massive stars. The explosion mechanism involves complex interplay between micro- and macroscopic physics. Numerical simulations have been used in an effort to understand the roles of each physics on driving explosions, and they have made a remarkable progress with increasing computational resources in the last decade. In fact, some of multi-dimensional CCSN simulations reproduced successful explosions without artifices. In this article, we review the current status of CCSN theory with paying a special attention to the recent progress, and then we describe key issues remaining to be addressed.

We have developed molecular Mott insulators with triangular lattice. One Mott insulator κ-(ET)₂ Ag₂(CN)₃ has an isotropic triangular lattice and exhibits a quantum spin liquid state with low-lying excitation. It shows Mott and superconducting transitions under pressure and strain. The static and dynamical spin susceptibilities scale to exchange interaction tunable under pressure. Another Mott insulator κ-(ET)₂ B (CN)₄ has one-dimensional anisotropy and exhibits spin dimerization at 5 K. It shows a first-order transition into an incommensurate antiferromagnetic state under magnetic field above 8 T. The magnetic field response can be the promising method to distinguish gapless spin liquid and gapped spin dimer states.

Recent technological advances in growing single crystal samples of Eu compounds have boosted progress in the research field on valance fluctuation and /or transition of the Eu compounds. Here, we review the electronic states of single-crystalline EuT₂X₂ (T: transition metal, X: Si or Ge) and related compounds, together with the effect of pressure on these compounds. The rare-earth ions are usually trivalent, but a divalent (Eu²⁺) electronic state is more stable than a trivalent (Eu³⁺) one in the Eu-based metallic compounds. The energy difference between the Eu²⁺ and Eu³⁺ states is, however, not very large. Therefore, it is possible to change the Eu valence from nearly divalent (Eu²⁺) to nearly trivalent (Eu³⁺) by applying pressure. Here we show several characteristic features of Eu compounds under pressure: the magnetic order is suppressed, as revealed by the Doniach phase diagram, the magnetic order changes to the first-order valence transition above a critical pressure, and the moderate heavy-fermion state appears around the magnetic quantum critical point. Recently, a new phase diagram for the Eu compounds was found under pressure, which might be due to a sharp valence crossover induced by pressure.

The ALPHA collaboration (Antihydrogen Laser Physics Apparatus), based at CERN (European Organization for Nuclear Research), has reported the world’s first successful manipulation of antimatter using the force of laser light. By creating and trapping >1,000 antihydrogen atoms, ALPHA has demonstrated that the motion of antihydrogen atoms can be controlled in the same way as in ordinary matter, using precisely controlled laser pulses. This technique has been used to cool antihydrogen atoms down to near absolute zero. The success of laser cooling antimatter atoms would lead to dramatic progress in antimatter research as well as to the development of new antimatter quantum technologies and to the creation of antimatter molecules.