An array of superconducting transition-edge sensor (TES) microcalorimeters is an attractive detector in research fields where high precision measurements are required. This paper introduces two examples of applying a 240-pixel TES microcalorimeter array (TES detector) to physics experiments using quantum beams. The first application is a series of experiments involving the precise X-ray spectroscopy of exotic atoms using three types of charged-particle beams (i.e., pion, kaon, and muon) at large-scale proton accelerator facilities: Paul Scherrer Institute and J-PARC. The improvement in measurement accuracy by an order of magnitude has brought about great progress in research on exotic atoms. The second application is an atomic-molecule collision experiment using atomic or molecular beams with a cryogenic electrostatic ion storage ring at RIKEN. This is the world's first attempt to apply a TES detector to the detection of "neutral low-energy atoms and molecules" instead of "photons", aiming to use it as a new high-resolution mass spectrometer.

A quantum internet will provide arbitrary accessibility of distributed quantum systems, enabling secure communication, quantum computing, quantum sensing, etc. The quantum link between distant systems is established by photons flying through optical fibers and satellites. In this review, I present fundamental methods to send, manipulate and detect photonic quantum states to build a quantum internet; especially, technologies related to superconducting photon detectors.

We have applied neuromagnetic field measurement, which has already been used in the medical field for the brain, to the spinal cord and peripheral nerves. By optimizing the equipment and analysis method to the axonal activity, it is now possible to evaluate the neural functions in patients with spinal cord and peripheral nerve diseases. Since there are many patients with spinal cord and peripheral nerve diseases, SQUID technology will make a significant contribution to medicine.

Moore's Law, doubling the number of transistors in a chip every two years, has contributed to the evolution of computer system architectures to date. The growth of such hardware implementation makes many optimization opportunities available to software developers. Unfortunately, we cannot expect sustainable transistor shrinking anymore; that is, the end of Moore's Law will come. Although device and manufacturing technologies continue to progress, some researchers predict that transistor shrinking may stop around 2030 to 2035 due to physical or economic reasons. The goal of this research is to open the door for post-CMOS ultrahigh-performance, low-power computing. Our approach is based on device/circuit/architecture-level co-designs by targeting an emerging device called the single-flux quantum (SFQ). We have successfully demonstrated several outstanding physical designs supporting over 30 GHz. This paper summarizes our research outcomes and discusses the future direction of next-generation computer system architecture.