Multiple-barrier and nanoscale superconducting devices

Since the pioneering studies of Josephson and Giaever, the development of electronic devices has been a key research area in superconductivity. In conventional metallic superconductors, highly reliable tunnel junction fabrication techniques have enabled the application of superconducting devices in astronomy and metrology and have allowed the development of large scale integrated circuits for fast digital processing. These sub-micron heterostructure fabrication processes have also made possible the study of superconducting devices containing two or more closely spaced barriers. Such structures allow the investigation of a wide range of novel effects and have led to the development of basic research areas and applications as diverse as electronic cryocoolers, coherent radiation emission and quantum computing. This paper will review the science which can be investigated using multiple-barrier superconducting devices and describe recent progress in the area