Revealing Josephson vortex dynamics in proximity junctions below critical current

Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles [1] which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (Magnetic Force Microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements.Comment: 11 pages, 3 figures, 1 table, 43 reference

Study of fire-resistance of reinforced concrete slab of a new type

Reinforced concrete structures with complex inner geometry under the effect of high temperatures considering void former materials were examined. The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ under the effect of high temperature heating in standard fire mode, considering the change of design pattern was carried out. Numerical study of concrete slab with given reinforcement and complex inner geometry was carried out with use of software packages based on finite element method. Temperature fields throughout the depth of cross section of the slab of new type of architectural and construction system ‘Monofant’ upon heating in standard fire mode for time interval 0-240 min. were obtained. The carrying capacity of sections exposed to high temperatures was determined by deformation method. Offered the algorithm that considers the transformation of design patterns depending on temperature values and excessive pressure in thermal insulation cavities taking into account influence of deformation fields on temperature distribution

Study of fire-resistance of reinforced concrete slab of a new type

Reinforced concrete structures with complex inner geometry under the effect of high temperatures considering void former materials were examined. The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ under the effect of high temperature heating in standard fire mode, considering the change of design pattern was carried out. Numerical study of concrete slab with given reinforcement and complex inner geometry was carried out with use of software packages based on finite element method. Temperature fields throughout the depth of cross section of the slab of new type of architectural and construction system ‘Monofant’ upon heating in standard fire mode for time interval 0-240 min. were obtained. The carrying capacity of sections exposed to high temperatures was determined by deformation method. Offered the algorithm that considers the transformation of design patterns depending on temperature values and excessive pressure in thermal insulation cavities taking into account influence of deformation fields on temperature distribution

НАПРУЖЕНО-ДЕФОРМОВАНИЙ СТАН АРХІТЕКТУРНО-КОМПОЗИЦІЙНОГО КОМПЛЕКСУ У ФОРМІ СТРІЧКИ МЕБІУСА

In this paper, a numerical study of the strain-stress state of a complex architectural and composite structure in the form of a Mobius strip, made of heavy structural concrete with polystyrene void formers, was carried out. The analysis of strain-stress state is carried out by the finite element method (FEM) in specialized software packages with additional processing of output data. The procedure for analyzing the strain-stress state of large volumetric FE models of building structures, taking into account the stress concentrators and the possibility of appearance, degenerate finite elements as a result of automatic triangulation, is given. Verification of the proposed algorithm by numerical and qualitative comparison of the results of calculations by different software packages was carried out. The fields of stress and displacement displacements obtained in different program packages showed sufficient convergence. The possibility of using this algorithm for the analysis of strain-stress state for other complex structures.В данной работе проведено численное исследование НДС сложного архитектурно-композиционного сооружения в форме ленты Мебиуса, выполненного из тяжелого конструкционного бетона с вкладышами из пенополистирола. Анализ НДС проведен методом конечных элементов (МКЭ) в специализированных программных комплексах с дополнительной обработкой выходных данных. Приведена методика анализа НДС больших объемных КЭ моделей строительных конструкций с учетом концентраторов напряжений и возможности появления вырожденных КЭ в результате автоматической триангуляцииУ даній роботі проведено чисельне дослідження НДС складної архітектурно-композиційної споруди у формі стрічки Мебіуса, виконаної з важкого конструкційного бетону з вкладишами з пінополістиролу. Аналіз НДС проведено методом скінченних елементів (МСЕ) в спеціалізованих програмних комплексах з додатковою обробкою вихідних даних. Наведено методику аналізу НДС великих об'ємних КЕ моделей будівельних конструкцій з урахуванням концентраторів напружень і можливості появи вироджених КЕ в результаті автоматичної тріангуляції

Use of information technologies for energetic portrait construction of cylindrical reinforced concrete shells

The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ was examined. The analysis of the advanced graphic, computing software packages was carried out. The possibility of joint applying these packages to the problem of sustainable conjunction study of a rational combination of the geometric parameters of the design-built system “Monofant” was analyzed. From the constructive point of view, the search for the structural element shape that provides a minimum material consumption under desired conditions is of some interest. The approach based on the energy criterion of rationalization was adopted to solve this problem. Fundamentally, new opportunities in the field of building structures optimization are offered with introduction of visual programming complexes adopted for designers (Grasshopper, Dynamo). Applying the described approach to the problem of rationalizing of the constructive system “Monofant” offers the opportunity of constructing, calculating, analyzing and rationalizing of construction that has complex external and internal geometry. An illustration of a possible approach is given in a specific numerical example

Use of information technologies for energetic portrait construction of cylindrical reinforced concrete shells

The analysis of strain-stress state of new type of architectural and construction system ‘Monofant’ was examined. The analysis of the advanced graphic, computing software packages was carried out. The possibility of joint applying these packages to the problem of sustainable conjunction study of a rational combination of the geometric parameters of the design-built system “Monofant” was analyzed. From the constructive point of view, the search for the structural element shape that provides a minimum material consumption under desired conditions is of some interest. The approach based on the energy criterion of rationalization was adopted to solve this problem. Fundamentally, new opportunities in the field of building structures optimization are offered with introduction of visual programming complexes adopted for designers (Grasshopper, Dynamo). Applying the described approach to the problem of rationalizing of the constructive system “Monofant” offers the opportunity of constructing, calculating, analyzing and rationalizing of construction that has complex external and internal geometry. An illustration of a possible approach is given in a specific numerical example

PRODUCTION OF METAL CHEMICAL WELDING ADDITIVE WITH NANODISPERSED PARTICLES OF TITANIUM DIOXIDE

When welding bridge structures automatic welding under a gumboil layer with metal chemical additive (MCA) is widely applied in the modern bridge building. MCA consists of a chopped welding wire (granulated material), which is powdered by modifying chemical additive of titanium dioxide (TiO₂) in the cylindrical mixer «drunk cask». Chemical composition of all welding materials including welding wire, gumboil, electrodes, are strictly normalized and controlled. However, the existing technology of producing MCA doesn’t allow precise controlling of its structure under working conditions and that causes an impact on the stability of welded connections properties. Therefore the aim of this work is to develop a technology to produce stable MCA structure. The paper compares the existing and proposed manufacturing techniques of the metal chemical additive (MCA) which is applied in automatic welding of butt connections for bridge structures. It is shown that production of MCA in a high-energy planetary mill provides more stable structure of the additive introduced into a welded joint. The granulometric analysis of the powder TiO₂ showed that when processing MCA in a planetary mill TiO₂ particles are crashed to nanodimensional order. This process is accompanied by crushing of granulated material too. The proposed method for production of MCA in a planetary mill provides stronger cohesion of dioxide with the granulate surface and, as a consequence, more stable MCA chemical structure. Application of MCA which has been mechanical intensified in a planetary mill, increases stability of mechanical properties, if compare with applied technology, in single-order by breaking point and almost twice by impact viscosity

Observation of Interacting Josephson vortex chains by magnetic force microscopy

The ability to control Josephson vortices is instrumental for development of superconducting cryoelectronics. However, direct visualization of multivortex states in Josephson junctions is a challenging task. Here, we employ a magnetic force microscopy (MFM) for the analysis of planar Josephson junctions. We observe a specific MFM response, seen as a chain of small rings. By changing the applied field, we show that the number of rings is equal to the number of flux quanta in the junction. Therefore, each ring represents an individual vortex in a one-dimensional vortex chain within the junction. Our observation demonstrates that the MFM technique can be used for visualization of Josephson vortices and for probing their spatial configurations and mutual interaction

Local Josephson vortex generation and manipulation with a Magnetic Force Microscope

International audienceJosephson vortices play an essential role in superconducting quantum electronics devices. Often seen as purely conceptual topological objects, 2π-phase singularities, their observation and manipulation are challenging. Here we show that in Superconductor-Normal metal-Superconductor lateral junctions Josephson vortices have a peculiar magnetic fingerprint that we reveal in Magnetic Force Microscopy (MFM) experiments. Based on this discovery, we demonstrate the possibility of the Josephson vortex generation and manipulation by the magnetic tip of a MFM, thus paving a way for the remote inspection and control of individual nano-components of superconducting quantum circuits

Revealing Josephson Vortex Dynamics in Proximity Junctions below Critical Current

Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles (Andreev, A. Sov. Phys. JETP 1965, 20, 1490) which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (magnetic force microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements