Dear Colleagues,

Superconducting elements have unique characteristics that are not available in conventional semiconductor electronics. The ability of superconducting nanostructures to operate at very high frequencies and provide an extremely strong non-linear response makes them ideal building blocks for unique systems for detecting and generating terahertz radiation. To realize the maximum performance of terahertz devices, high-quality nanostructures with controlled and reproducible parameters are required. Modern manufacturing technologies (electron-beam lithography, plasma etching, etc.) make it possible to create terahertz devices with quantum-limited sensitivity and superconducting quantum interference devices (SQUIDs), and to develop novel metamaterial elements with tunable characteristics as well as a number of new superconducting elements and devices for detecting and generating a terahertz signal.

The development of ultra-sensitive terahertz (THz) receivers and oscillators is now one of the most intensively and successfully explored areas of superconducting electronics. Superconducting elements offer an extremely high characteristic frequency and very strong nonlinearity. This makes it possible to develop systems for receiving a THz signal with unique parameters unattainable for devices based on other principles. Currently, the most developed are two types of superconducting mixers: SIS mixers for frequencies from 0.2 to 1.2 THz and hot-electron bolometer (HEB) mixers for frequencies of 1–5 THz. Both types of mixers are mainly used in radio astronomy, where low receiver noise is a critical issue. The parameters requested by astronomers can only be realized using superconducting mixing elements with extremely low intrinsic noise, determined by the nature of the elements and cryogenic operating temperature.

The development of superconducting electronics makes it possible to create a superconducting integrated receiver (SIR), which combines all receiver components in one microcircuit: a planar antenna, an SIS mixer, a superconducting local oscillator based on a flux-flow oscillator (FFO), and a SIS harmonic mixer for FFO phase locking. SIR sensitivity and spectral resolution have been demonstrated by a atmospheric limb sounding onboard a high-altitude balloon and in the laboratory for detailed spectral measurements of THz radiation emitted from the BSCCO mesa.

Currently, the world is experiencing an explosive growth in the volume of research on the use of post-silicon electronics technologies to improve information processing methods. Superconducting systems play a special role in the development of this direction, and a number of promising developments are built around them. Superconducting Josephson circuits act as key elements in advanced systems that use quantum effects at various levels, and are aimed at implementing artificial intelligence as well as solving a wide range of problems in processing large amounts of data, optimization, classification, machine learning, chemistry and materials science on a fundamentally new basis level. New types of qubits, artificial neurons and synapses based on superconductors and methods for their control are being developed. Work is underway to create energy-efficient superconducting digital electronics for the monitoring and primary processing of information coming from superconducting sensor arrays and quantum computing cores, which in the future may make it possible to abandon the use of unacceptably cumbersome (in the case of full-scale systems) peripherals.

The objective of this Special Issue is to present studies in the field of applied superconducting electronics, including methods for the nanofabrication of superconducting elements and circuits. Researchers are invited to submit their manuscripts to this Special Issue and contribute theoretical models, technological developments, reviews, and studies.

Prof. Dr. Valery P. Koshelets
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.