There are high expectations for the development of fault-tolerant quantum computers that can solve diverse, complex, and large-scale problems. Achieving this requires both high-fidelity and highly-integrated qubits. Research and development is progressing in various physical systems, and semiconductor qubits are one of the leading candidates. This report provides an overview of the basic knowledge of semiconductor qubits, and then introduces global research and development trends related to high fidelity, various efforts toward integration, and research and development of peripheral technologies.

Infrared detectors onboard earth observation satellites are required to have excellent performance. JAXA is studying the Type II superlattice infrared detector as a next-generation infrared detector to replace the HgCdTe detector that has been widely used in conventional earth observation satellites. This paper describes the principle and current development status of the Type II superlattice infrared detector in JAXA.

In the midst of the further digitization of society, as observed in the remarkable progress of Artificial Intelligence (AI), the role of light and photonics is expanding beyond communication and measurement to include computing. This paper reviews the latest developments in research aimed at enhancing reinforcement learning and decision-making tasks, both of which are fundamental functions of AI. Specifically, we introduce the resolution of bandit problem via chaotic itinerary in semiconductor lasers and provides an overview of collective decision-making that leverages quantum interference of light.

This paper reviews our recent research about the formation and optical characteristics of GaN:Eu/GaN nanowires (NWs) by organometallic vapor phase epitaxy for application in GaN-based red LEDs. Two types of GaN:Eu/GaN NWs with different configurations are introduced, core-shell and axial geometries. The configuration of GaN:Eu layers on GaN core NWs can be controlled by changing the growth conditions, and affects the properties of Eu luminescence in the GaN NWs. Next, the fabrication process of the NW LEDs towards future possible realization of flexible devices is established, including an etch-back process of the PDMS membranes to expose the top p-GaN contact layers. Finally, a proto-type of p-GaN/GaN:Eu/n-GaN NW LEDs on sapphire substrates is fabricated to characterize the device properties. Sharp red luminescence at room temperature from Eu³⁺ ions is observed under current injection.

Surface acoustic waves (SAWs) occupy an important role in the electronic device industry. Recently, SAWs have also been applied to basic research in various areas. Such research mainly employs single-frequency sinusoidal SAWs. On the other hand, it is possible to generate SAWs with a variety of shapes by devising generation methods. The use of SAWs with various shapes has the potential to further expand the range of research that has been conducted with SAWs. As an example, this fundamental lecture focuses on our recently reported technique for generating single pulses of SAWs, and describes the technique from the underlying generation principle to the actual generation method of single-SAW pulses.