7th International School and Conference "Saint-Petersburg OPEN 2020" on Optoelectronics, Photonics, Engineering and Nanostructures was held on April 27 - 30, 2020. The Organizer of the conference is the Alferov Federal State Budgetary Institution of Higher Education and Science Saint Petersburg National Research Academic University of the Russian Academy of Sciences. Initially, the School and Conference was supposed to be held in full-time format at the Alferov Academic University (Saint-Petersburg, Russia), as it happened in the past. However, due to the restrictions imposed by the city authorities on holding mass events due to the threat of the spread of the COVID-19 infection, the conference committees decided to move the conference to the online format. The conference consisted of poster reports presented by the participants and online oral presentations by invited speakers. Posters and video reports of the participants were posted on the conference website. Invited speakers made their presentations online. During their speeches, participants could discuss and ask questions in the chat. The School and Conference included a series of invited talks given by leading professors with the aim to introduce young scientists with actual problems and major advances in physics and technology.

Proceedings of the SPIE PHOTONICS EUROPE Conference on Biophotonics in Point-of-Care, 6-10 April 2020, Online Only, France. Proc. SPIE volume 11361

The goal of this International Roadmap for Devices and Systems (IRDS) chapter is to survey, catalog, and assess the status of technologies in the areas of cryogenic electronics and quantum information processing. Application drivers are identified for sufficiently developed technologies and application needs are mapped as a function of time against projected capabilities to identify challenges requiring research and development effort. Cryogenic electronics (also referred to as low-temperature electronics or cold electronics) is defined by operation at cryogenic temperatures (below −150 °C or 123.15 K) and includes devices and circuits made from a variety of materials including insulators, conductors, semiconductors, superconductors, or topological materials. Existing and emerging applications are driving development of novel cryogenic electronic technologies. Information processing refers to the input, transmission, storage, manipulation or processing, and output of data. Information processing systems to accomplish a specific function, in general, require several different interactive layers of technology. A top-down list of these layers begins with the required application or system function, leading to system architecture, micro- or nano-architecture, circuits, devices, and materials. A fundamental unit of information (e.g., a bit) is represented by a computational state variable, for example, the position of a bead in the ancient abacus calculator or the voltage (or charge) state of a node capacitance in CMOS logic. A binary computational state variable serves as the foundation for von Neumann computational system architectures that dominated conventional computing. Quantum information processing is different in that it uses qubits, two-state quantum-mechanical systems that can be in coherent superpositions of both states at the same time, which can have computational advantages. Measurement of a qubit in a given basis causes it to collapse to one of the basis states. Technology categories covered in this report include: • Superconductor electronics (SCE) • Cryogenic semiconductor electronics (Cryo-Semi) • Quantum information processing (QIP)

Continuing miniaturization of electronic devices, together with the quickly growing number of nanotechnological applications, demands a profound understanding of the underlying physics. Most of the fundamental problems of modern condensed matter physics involve various aspects of quantum transport and fluctuation phenomena at the nanoscale. In nanostructures, electrons are usually confined to a limited volume and interact with each other and lattice ions, simultaneously suffering multiple scattering events on impurities, barriers, surface imperfections, and other defects. Electron interaction with other degrees of freedom generally yields two major consequences, quantum dissipation and quantum decoherence. In other words, electrons can lose their energy and ability for quantum interference even at very low temperatures. These two different, but related, processes are at the heart of all quantum phenomena discussed in this book.This book presents copious details to facilitate the understanding of the basic physics behind a result and the learning to technically reproduce the result without delving into extra literature. The book subtly balances the description of theoretical methods and techniques and the display of the rich landscape of the physical phenomena that can be accessed by these methods. It is useful for a broad readership ranging from master's and PhD students to postdocs and senior researchers.

The materials of The International Scientific – Practical Conference is presented below.

The Conference reflects the modern state of innovation in education, science, industry and social-economic sphere, from the standpoint of introducing new information technologies.

It is interesting for a wide range of researchers, teachers, graduate students and professionals in the field of innovation and information technologies.

We study material gain of a novel type of quantum heterostructures of mixed (0D/2D) dimensionality referred to as quantum well-dots (QWDs). To evaluate the material gain in a broad range of injection currents (30–1200 A cm−2 per-layer) we studied edge-emitting lasers with various numbers of InGaAs/GaAs QWD layers in the active region and different waveguide designs. The dependence of the material gain on the current is well fitted by an empirical exponential equation similar to the one used for quantum dots (QDs) in the whole range of injection current densities. The estimated QWD transparency current-density-per-layer of 31 A cm−2 ranks between the values reported for quantum wells and QDs. The maximal QWD material gain as high as 1.1·104 cm−1 has been measured. The results obtained confirm specific gain properties of InGaAs QWDs making them promising active media for lasers, superluminescence diodes and optical amplifiers.

Electronic states in a novel type of quantum-size heterostructures referred to as InGaAs quantum welldots (QWDs) were experimentally studied using absorption in stripe waveguides of different lengths based on a single, double, five, and ten QWD layers. The value of the modal absorption was measured to be 70 cm−1 and 90 cm−1 for ground-state transition and high-energy one, respectively. The structure of electronic states in the QWDs is also analyzed by polarization-resolved waveguide absorption and the dependence of a polarization degree on the chip length is discussed. TM polarization of the heavyhole- based optical transition photoresponse observed in the long waveguides is attributed to the light depolarization due to the scattering on the QWD heterointerfaces.

Based on the quantum-mechanical theory of electron transfer (ET), the parameter was proposed to describe the electrochemical activity of doped graphenes. The parameter is calculated using the density of states (DOS), local density of state (LDOS) values, which are in turn obtained from the density functional theory (DFT) calculations and reorganization energies of redox system. DOS describes the contribution of the electronic structure of the electrode to the ET process, while the LDOS describes the electron density contribution of the atoms at some distance from the surface electrode. Reorganization energy corresponds to the restriction of solvation shell and bonds in redox system due to ET process. The overall contribution of these parameters enables a comprehensive assessment of the activity that is acceptable for semi-quantitative analysis. Calculations have shown that the proposed activity parameter correlates well with the calculated ET rate constants. Theoretical study of the oxygen reduction reaction (ORR) on graphene doped with p-elements in the framework of quantum-mechanical theory showed that ET activity decreases in the series P-Gr > S-Gr > N-Gr > B-Gr > O-Gr > Gr. According to our estimates, the mixed or adiabatic regime of ET is probably observed on doped graphenes for all steps of ORR. Using N- and B-graphenes as an example and activity parameter, the influence of the applied potential and the atomic fraction of the doped element on the ET activity are studied.

A new method of surface plasmon waves excitation based on the photoluminescence of a nanostructured metal surface is proposed. The method was demonstrated using a plasmonic crystal formed by an array of nanoholes in 200 nm thick Ag film (supporting SPP resonances) covered by a 10 nm thin Au layer (for efficient excitation of photo-induced luminescence). It was shown that using this method it is possible: (i) to excite SPP waves in ultra-large spectral range, (ii) to measure plasmonic crystal optical properties, (iii) to measure optical characteristics of the SPP waves.

Plasmonic interferometry is a rapidly growing area of research with a huge potential for applications in the terahertz frequency range. In this Letter, we explore a plasmonic interferometer based on graphene field effect transistor connected to specially designed antennas. As a key result, we observe helicity- and phase-sensitive conversion of circularly polarized radiation into dc photovoltage caused by the plasmon-interference mechanism: two plasma waves, excited at the source and drain part of the transistor, interfere inside the channel. The helicity-sensitive phase shift between these waves is achieved by using an asymmetric antenna configuration. The dc signal changes sign with inversion of the helicity. A suggested plasmonic interferometer is capable of measuring the phase difference between two arbitrary phase-shifted optical signals. The observed effect opens a wide avenue for phase-sensitive probing of plasma wave excitations in two-dimensional materials.

We report the discovery of a GeV-associated phenomenon which is strong (up to an order) stochastic reversible enhancements of photoluminescence intensity in a single GeV diamond synthesized with the high-pressure, high-temperature technique. We were lucky to observe this effect with only one crystal among dozens of similar microdiamonds. Each rise and fall of the intensity above its stable moderate level may be referred to as a superflare with smooth dynamics of the transients which develop on the timescale of seconds. These flares tend to recur infinitely at ambient conditions under cw-laser excitation above a certain input power threshold. To explain this phenomenon we propose a theory of intrinsic optical instabilities which develop in a dense ensemble of quantum emitters.

We analyze the benefits and shortcomings of a thermal control in nanoscale electronic conductors by means of the contact heating scheme. Ideally, this straightforward approach allows one to apply a known thermal bias across nanostructures directly through metallic leads, avoiding conventional substrate intermediation. We show, by using the average noise thermometry and local noise sensing technique in InAs nanowire–based devices, that a nanoscale metallic constriction on a SiO2 substrate acts like a diffusive conductor with negligible electron-phonon relaxation and non-ideal leads. The non-universal impact of the leads on the achieved thermal bias—which depends on their dimensions, shape and material composition—is hard to minimize, but is possible to accurately calibrate in a properly designed nano-device. Our results allow to reduce the issue of the thermal bias calibration to the knowledge of the heater resistance and pave the way for accurate thermoelectric or similar measurements at the nanoscale.

Shot-noise measurements are widely used for the characterization of nonequilibrium configurations in electronic conductors. The recently introduced quantum tomography approach was implemented for the studies of electronic wave functions of few-electron excitations created by periodic voltage pulses in phase-coherent ballistic conductors based on the high-quality GaAs two-dimensional electron gas. Still relying on the manifestation of Fermi correlations in noise, we focus on the simpler and more general approach beneficial for local measurements of energy distribution (ED) in electronic systems with arbitrary excitations with well-defined energies and random phases. Using biased diffusive metallic wire as a test bed, we demonstrate the power of this approach and extract the well-known double-step ED from the shot noise of a weakly coupled tunnel junction. Our experiment paves the way for local measurements of generic nonequilibrium configurations applicable to virtually any conductor.

Spaser nanoparticles, with ultranarrow spectral line width, small size and good biocompatibility, offer a bright prospect as potential biological probes. Sadly, over 10 years since the first demonstration, how the structure components determine their optical performance has not been clarified. Here the effects of gain layer thickness and dye emitter density on the lasing behavior and photostability of spaser nanoparticles are theoretically and experimentally addressed. Results show that for a 16 nm gold-core cavity, gain layer of 10–15 nm is adequate to maximize the spaser emission. For this type of nanoparticle–spaser system, the minimal number of dye emitters per particle, referred to as “dye threshold”, is also vital to spasing action besides the “pump threshold” of laser power. Moreover, dye emitter distribution within the gain layer could be another approach to further improve spaser performance. These contributions give us an opportunity to profoundly understand the physical essence of spaser nanoparticles and to optimize their performance for further biology application.