Superconductive electronics is an extensive field covering both low- and high-temperature superconductors (HTS), and their applications in quantum interference devices, power transmission, microwave filters and logic circuits. The microscopic origins of superconductivity are explained by Bardeen–Cooper–Schieffer (BCS) theory whereas a macroscopic treatment is provided by the Ginzburg–Landau theory. The London equations can explain the well-known Meissner effect of exclusion of magnetic induction by superconductors. A widely used device in superconductive electronics is the Josephson junction (JJ). The DC and AC Josephson effects as well as the inverse AC Josephson effects are described. The application of DC and AC superconducting quantum interference devices (SQUIDs) in magnetometry are discussed. Rapid single flux quantum (RSFQ) logic, touted as a competitive beyond-CMOS technology in nanoelectronics, is briefly surveyed.
Superconductive electronics is an extensive field covering both low- and high-temperature superconductors (HTS), and their applications in quantum interference devices, power transmission, microwave filters and logic circuits. The microscopic origins of superconductivity are explained by Bardeen–Cooper–Schieffer (BCS) theory whereas a macroscopic treatment is provided by the Ginzburg–Landau theory. The London equations can explain the well-known Meissner effect of exclusion of magnetic induction by superconductors. A widely used device in superconductive electronics is the Josephson junction (JJ). The DC and AC Josephson effects as well as the inverse AC Josephson effects are described. The application of DC and AC superconducting quantum interference devices (SQUIDs) in magnetometry are discussed. Rapid single flux quantum (RSFQ) logic, touted as a competitive beyond-CMOS technology in nanoelectronics, is briefly surveyed.
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.
The Rapid Single-Flux-Quantum logic (RSFQ) presents an efficient way to achieve ultra fast digital operations. This logic uses the macroscopic effects which can be found in nano-structured superconductor devices such as the Josephson AC and DC effects, and the magnetic flux quantization. As the typical time of the Josephson junction quantized phase leap 2π is in the order of picoseconds, the RSFQ circuits can operate with clock frequencies in the order of hundreds of GHz. This invited paper focuses on basic principles of superconducting RSFQ logic as well as on typical applications, such as the signal conversion or petaflops computing systems. In addition we point out the benefits of the semi-metallic NbN-TaxN-NbN Josephson junction technology, which has been developed at CEA-INAC in Grenoble.
Superconducting quantum sensors use flux quantization, the Josephson effect and low-loss microwave circuits to measure magnetic flux, microwave signals and photon flux close to fundamental limits. In this review we follow the field from the Bardeen–Cooper–Schrieffer theory and the discovery of Josephson tunnelling to SQUID magnetometers, microwave kinetic inductance detectors and quantum-limited parametric amplifiers. We explain how dc and rf SQUIDs, superconducting resonators, and Josephson and kinetic-inductance amplifiers work, and we describe one measurement chain that covers them all, with separate excitation, response, amplification, control and readout paths and a fluxlocked-loop variant for SQUIDs. Flux and field noise, noise-equivalent power, added noise, bandwidth and dynamic range are defined and compared using numbers taken directly from the primary literature, together with the conditions under which they were measured. We then survey applications in biomagnetism, astronomical imaging, qubit readout and dark-matter searches, and close with the open problems of scalability, environmental noise and fair benchmarking.
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.
Applications to electronics are mainly based on Josephson junctions special properties. As it was pointed before, a single Josephson junction is a perfect voltage to frequency converter (AC Josephson effect). One example is the application into RF amplifiers where a radiofrequency signal generates a magnetic flux in a circuit coupled to, for example, DC-SQUID. Josephson effect allows converting the flux into the SQUID to an amplified voltage signal, proportional to the number of 0. That is the base of the microwave applications. The SQUID inductance together with the capacitance of the junction, allows also using the device as resonator.