Resonance energy and charge pumping through quantum SINIS contacts

We propose a mechanism of quantum pumping mediated by the spectral flow in a voltage-biased SINIS quantum junction and realized via the sequential closing of the minigaps in the energy spectrum in resonance with the Josephson frequency. We show that the dc current exhibits giant peaks at rational voltages

Multiple Vortex Cores in 2D Electronic Systems with Proximity Induced Superconductivity

The structure of a proximity induced vortex core in a two-dimensional (2D) metallic layer covering a superconducting half-space is calculated. We predict formation of a multiple vortex core characterized by two-scale behavior of the local density of states (LDOS). For coherent tunnelling between the 2D layer and the bulk superconductor, the spectrum has two subgap branches while for incoherent tunnelling only one of them remains. The resulting splitting of the zero-bias anomaly and the multiple peak structure in the LDOS should be visible in the tunnelling spectroscopy experiments.Comment: 13 pages, 4 figure

Abrikosov vortex escape from a columnar defect as a topological electronic transition in vortex core

We study microscopic scenario of vortex escape from a columnar defect under the influence of a transport current. For defect radii smaller than the superconducting coherence length the depinning process is shown to be a consequence of two subsequent topological electronic transitions in a trapped vortex core. The first transition at a critical current $j_L$ is associated with the opening of Fermi surface segments corresponding to the creation of a vortex--antivortex pair bound to the defect. The second transition at a certain current $j_d > j_L$ is caused by merging of different Fermi surface segments, which accompanies the formation of a freely moving vortex.Comment: 5 pages, 4 figure

Single-electron transport through the vortex core levels in clean superconductors

We develop a microscopic theory of single-electron transport in N-S-N hybrid structures in the presence of applied magnetic field introducing vortex lines in a superconductor layer. We show that vortex cores in a thick and clean superconducting layer are similar to mesoscopic conducting channels where the bound core states play the role of transverse modes. The transport through not very thick layers is governed by another mechanism, namely by resonance tunneling via vortex core levels. We apply our method to calculation of the thermal conductance along the magnetic field.Comment: 4 pages, 1 figur

Anderson localization of a weakly interacting one dimensional Bose gas

We consider the phase coherent transport of a quasi one-dimensional beam of Bose-Einstein condensed particles through a disordered potential of length L. Among the possible different types of flow identified in [T. Paul et al., Phys. Rev. Lett. 98, 210602 (2007)], we focus here on the supersonic stationary regime where Anderson localization exists. We generalize the diffusion formalism of Dorokhov-Mello-Pereyra-Kumar to include interaction effects. It is shown that interactions modify the localization length and also introduce a length scale L* for the disordered region, above which most of the realizations of the random potential lead to time dependent flows. A Fokker-Planck equation for the probability density of the transmission coefficient that takes this new effect into account is introduced and solved. The theoretical predictions are verified numerically for different types of disordered potentials. Experimental scenarios for observing our predictions are discussed.Comment: 20 pages, 13 figure

Charged-Surface Instability Development in Liquid Helium; Exact Solutions

The nonlinear dynamics of charged-surface instability development was investigated for liquid helium far above the critical point. It is found that, if the surface charge completely screens the field above the surface, the equations of three-dimensional (3D) potential motion of a fluid are reduced to the well-known equations describing the 3D Laplacian growth process. The integrability of these equations in 2D geometry allows the analytic description of the free-surface evolution up to the formation of cuspidal singularities at the surface.Comment: latex, 5 pages, no figure

Re-entrant localization of single particle transport in disordered Andreev wires

We study effects of disorder on the low energy single particle transport in a normal wire surrounded by a superconductor. We show that the heat conductance includes the Andreev diffusion decreasing with increase in the mean free path $\ell$ and the diffusive drift produced by a small particle-hole asymmetry, which increases with increasing $\ell$. The conductance thus has a minimum as a function of $\ell$ which leads to a peculiar re-entrant localization as a function of the mean free path.Comment: 4 pages, 2 figure

Вклад советской металлургии в создание и начало серийного производства советского тяжелого танка серии «КВ» (1939 – 1941 гг.)

The KV heavy tank stays among the legends of the Great Patriotic War and one of the most recognizable combat vehicles of those years. The assessment of the tank, its design features and practice of operation, in scientific, popular science literature, and journalism, is still ambiguous: from praise to denial. Historical memory of this combat vehicle is actively living its life not only on pages of the books, but also in the virtual space, in the branches of thematic Internet forums and computer games. The heavy tank of KV series was developed and put into service at the very end of 1939. A new grade of 42S armor steel was created especially for it, which was distinguished by a relatively low content of alloying elements and high adaptability for mass production. The authors seriously studied the stages of armor production and the difficulties in its creation. They show the enormous contribution of metallurgists to the creation of a combat vehicle. As a result of engineering research and the decisive contribution of metallurgy, a formidable machine was obtained, possessing thick armor (75 mm) and quite powerful armament (76.2 mm cannon). At the same time, the tank had a whole range of disadvantages that reduce the effectiveness of its combat use. The general lack of development of the design and archaic technological solutions created serious problems both in the production and in the subsequent operation of this tank. History and tradition of searching the tank allows taking a fresh look at the long glorious traditions of the national engineering school in the field of metallurgy, and its decisive contribution to the Victory in the Great Patriotic War. © The Author(s), 2021.Funding: The historical part of the work was supported by the Russian Foundation for Basic Research within the framework of grant No. 19-09-00050; the metallurgical part of the work was performed within the framework of the program “Spin” No. AAAA-A18-118020290104-2

Vortex Core States in Superconducting Graphene

The distinctive features of the electronic structure of vortex states in superconducting graphene are studied within the Bogolubov-de Gennes theory applied to excitations near the Dirac point. We suggest a scenario describing the subgap spectrum transformation which occurs with a change in the doping level. For an arbitrary vorticity and doping level we investigate the problem of existence of zero energy modes. The crossover to a Caroli - de Gennes - Matricon type of spectrum is studied.Comment: 4 pages, 2 figure

Non-exponential spin relaxation in magnetic field in quantum wells with random spin-orbit coupling

We investigate the spin dynamics of electrons in quantum wells where the Rashba type of spin-orbit coupling is present in the form of random nanosize domains. We study the effect of magnetic field on the spin relaxation in these systems and show that the spatial randomness of spin-orbit coupling limits the minimum relaxation rate and leads to a Gaussian time-decay of spin polarization due to memory effects. In this case the relaxation becomes faster with increase of the magnetic field in contrast to the well known magnetic field suppression of spin relaxation.Comment: published version, minor change