Advances in superconductor quantum and thermal detectors for analytical instruments

Abstract

Analytical instruments or scientific instruments are indispensable for scientific research and industry. The analytical instruments require a detector that converts physical quantities to be measured (measurands) to electric signals. This Tutorial describes the basics of quantum and thermal detectors, the operation principles of superconductor detectors, and the ultimate performance of state-of-art analytical instruments with superconductivity. We still face fundamental issues, such as the classical Fano factor, the relation between energy gap and mean carrier creation energy, quasiparticle dynamics, and the intermediate state in the middle of superconducting transition; and engineering issues, such as the small sensitive area and the spatially nonuniform response. Nevertheless, enormous efforts have matured superconductor detectors, which enables us to solve the inherent problems of conventional analytical instruments. As an example of the analytical results, we describe x-ray spectroscopy and mass spectrometry at our institute by using three detector types: superconductor tunnel junction, transition edge sensor, and superconductor strip. Microwave kinetic inductance and metallic magnetic calorimetric types are also described. The analytical results may contribute to a wide range of fields, such as dentistry, molecular biology, energy-saving society, planetary science, and prebiotic organic molecules in space.