This paper gives a brief review of superconducting electronics in research and industry. Examples will show how science benefits from the development and how superconducting devices have found their way into industry and to some commercial products. Impact in terms of enabling new research in other fields (e.g. radio astronomy, medicine), in industry (certification, safety, metrology, etc) and in terms of market will be addressed. From the examples, two fields will be emphasized: superconducting detectors for astronomy and the superconducting quantum interference devices (SQUIDs) employed for different applications.
This paper gives a brief review of superconducting electronics in research and industry. Examples will show how science benefits from the development and how superconducting devices have found their way into industry and to some commercial products. Impact in terms of enabling new research in other fields (e.g. radio astronomy, medicine), in industry (certification, safety, metrology, etc) and in terms of market will be addressed. From the examples, two fields will be emphasized: superconducting detectors for astronomy and the superconducting quantum interference devices (SQUIDs) employed for different applications.
It has been nearly 110 years since the discovery of superconductors, and more than 30 years since the discovery of high temperature superconductors (HTS). Great progress has been made in the application of superconducting electronics in the last two decades. HTS microwave devices have shown much higher perfomance than the traditional ones and have found their ways to the industry applications in mobile communication, radar, and special communication applications. Owing to the ultrahigh sensitivity to magnetic fields and currents, superconducting quantum interference devices (SQUIDs) have been used as the irresplacible sensors in geological surveying, magnetic resonanc imaging, biomagnetic imaging, and other areas. The sensitivity of superconducting radiation detectors such as superconducting SIS mixer, superconducting hot electron bolometer, superconducting transition edge sensor, superconducting nanowire single photon detector, and superconducting microwave kinetic inductance detector are near the quantum limitation. They are now key technology in geophysics, astrophysics, quantum information science, biomedicine, and so on. Superconducting Josephson parametric amplifier has become a key element for superconducting quantum computing. Superconducting integrated circuit has been included in the international roadmap for devices and systems, and shows that having the potential to become one of the mainstreams for post-Moore information processing technology. In metrology, superconducting Josephson effect and Josephson junction array devices have been widely used in the redefinition of quantum voltage reference and basic units of the International system of Units. Superconducting electronics plays an important role in the current quantum information technology boom, which in turn promotes the development of superconducting electronics. This review will brief introduce the research and application of superconducting electronics in China in recent years.
Sensing and metrology play an important role in fundamental science and applications, by fulfilling the ever-present need for more precise data sets, and by allowing to make more reliable conclusions on the validity of theoretical models. Sensors are ubiquitous, they are used in applications across a diverse range of fields including gravity imaging, geology, navigation, security, timekeeping, spectroscopy, chemistry, magnetometry, healthcare, and medicine. Current progress in quantum technologies inevitably triggers the exploration of quantum systems to be used as sensors with new and improved capabilities. This perspective initially provides a brief review of existing and tested quantum sensing systems, before discussing future possible directions of superconducting quantum circuits use for sensing and metrology: superconducting sensors including many entangled qubits and schemes employing Quantum Error Correction. The perspective also lists future research directions that could be of great value beyond quantum sensing, e.g. for applications in quantum computation and simulation.
Abstract Superconductor electronics combines passive and active superconducting components and sometimes normal resistors into functional circuits and systems that also include room-temperature electronics for amplification, power sources, necessary controls, etc., usually computer operated. Furthermore, complete systems include magnetic and electromagnetic shielding, cryogenic enclosures, and increasingly a cryocooler in self-contained units. Components or devices of low or high critical temperature superconductors include inductances (coils), passive transmission lines, resonators, antennae, filters, as well as active elements: Josephson junctions, Josephson oscillators, and superconducting quantum interference devices. Of multiple demonstrated applications, mostly but not only in science and metrology, currently most successful are voltage standards, astronomy detectors and large telescope cameras, instruments for material characterization, and magnetometers for geomagnetic prospecting. Major current efforts concentrate on energy-efficient high-end computing and quantum computing. The outcomes of these efforts are likely to be known in the course of the following decade.
SQUIDs (superconducting quantum interference devices) have been in use for more than half a century and constitute one of the first macroscopic quantum devices. SQUIDs operating at millikelvin temperatures can act as qubits for quantum computers and the recent reports of more than 50 qubit circuits indicate how far the technology has developed. In this talk, the author will describe two other applications of SQUIDs as quantum detectors, focusing on single spin and single photon energy resolving detection. Most superconducting devices rely on tri-layer Josephson tunnel junctions which are not easily scalable to the nanoscale. We have developed a Josephson junction fabrication method, based on electron beam lithography or focused ion beam milling of a single thin film of superconductor (Nb generally) which can provide sizes down to 50 nm. These devices are particularly relevant for two main applications in quantum technology and metrology. First, by shrinking the size of the SQUID loop and the junctions to around 200 nm, the sensitivity of the SQUID for magnetization measurements is improved to the level where a single electron spin flip may be detected. This is possible at the relatively elevated temperature of 4K.
We are working with Surrey University to implant single magnetic ions within the SQUID loop to provide a platform to test this combination as the basis for a new form of qubit operating at higher temperatures than the conventional Transmon superconducting devices. A second SQUID based detector which we are developing is an inductive transition edge sensor device (ISTED) for energy resolving measurements of single photons. This is based on the development of conventional transition edge sensors where we detect the change of the penetration depth of a small thin film of superconductor when it absorbs a photon. In this way, a major source of noise in conventional TES may be avoided since the absorber remains in the superconducting state at all times. In this way we have demonstrated single photon detection at 633 nm with 0.1eV resolution at operating temperature of 7.5K.
The CSIRO Applied Superconductivity Group has a long-term effort in research and development of superconducting electronic devices and systems for various practical applications. In this talk, I will give an overview of CSIRO research activities in developing high-Tcsuperconducting (HTS) Josephson junction devices for various applications. I will firstly describe the CSIRO-developed HTS step-edge Josephson junction technology and its basic application in Superconducting Quantum Interference Devices (SQUIDs). I will then describe in more detail our recent research progress on developing high-Tcsuperconducting (HTS) Josephson devices for microwave and terahertz (THz) applications.