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Smorodin A.V.,Okinawa Institute of Science and Technology | Rybalko A.S.,Bverkin Institute For Low Temperature Physics And Engineering | Konstantinov D.,Okinawa Institute of Science and Technology
Journal of Low Temperature Physics | Year: 2017

We report an experimental study of the electrical properties of liquid helium-4 in the temperature range 1.2–3 K. The experiment is carried out in the millimeter wave range using a whispering gallery mode dielectric resonator, and the complex permittivity of liquid helium is extracted from the data using the resonant perturbation method. The results for the temperature dependence of the dielectric constant are consistent with the previous studies. In addition, we find strong enhancement of the loss tangent around the superfluid transition temperature. © 2017 Springer Science+Business Media New York


Chishko K.A.,Bverkin Institute For Low Temperature Physics And Engineering | Antsygina T.N.,Bverkin Institute For Low Temperature Physics And Engineering | Poltavskaya M.I.,Bverkin Institute For Low Temperature Physics And Engineering
Journal of Low Temperature Physics | Year: 2017

We apply the model of a crystalline polytype built of close-packed 2D monoatomic basal planes with triangular lattice to interpret the anomalous thermodynamical and mechanical properties of solid hexagonal close-packed (HCP) (Formula presented.). The polytype is a 3D stack of the basal planes, and its structure can be built from the simplest periodic packing (HCP, FCC, 4H, 5H, 6R, (Formula presented.) etc.) up to random stacking fault system (RSFS) totally aperiodic in only c-direction perpendicular to the basal planes. RSFS is a crystal without microscopic translation symmetry along c-axis, i.e., entirely disordered in only one spatial direction. Despite of packing disorder, c-direction remains the crystallographic axis of third order at arbitrary sequence of the 2D plates in the whole stack. In a long-wave limit the HCP polytype can be treated as 3D anisotropic continuum, as a result its phonon spectrum and Helmholtz free energy have been calculated. The temperature dependence of the phonon pressure is calculated theoretically and compared with experimental data. A quantitative agreement between the theory and the experiment is achieved. Mechanical properties of (Formula presented.) crystals in the framework of the polytype model are briefly discussed. © 2017 Springer Science+Business Media New York


Gonzalez-Zalba M.F.,Hitachi Cambridge Laboratory | Shevchenko S.N.,Bverkin Institute For Low Temperature Physics And Engineering | Shevchenko S.N.,University of Kharkiv | Shevchenko S.N.,RIKEN | And 6 more authors.
Nano Letters | Year: 2016

Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stückelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 ≈ 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology. © 2016 American Chemical Society.


PubMed | Bverkin Institute For Low Temperature Physics And Engineering, CEA Grenoble, University of Cambridge, RIKEN and Hitachi Cambridge Laboratory
Type: Journal Article | Journal: Nano letters | Year: 2016

Quantum mechanical effects induced by the miniaturization of complementary metal-oxide-semiconductor (CMOS) technology hamper the performance and scalability prospects of field-effect transistors. However, those quantum effects, such as tunneling and coherence, can be harnessed to use existing CMOS technology for quantum information processing. Here, we report the observation of coherent charge oscillations in a double quantum dot formed in a silicon nanowire transistor detected via its dispersive interaction with a radio frequency resonant circuit coupled via the gate. Differential capacitance changes at the interdot charge transitions allow us to monitor the state of the system in the strong-driving regime where we observe the emergence of Landau-Zener-Stckelberg-Majorana interference on the phase response of the resonator. A theoretical analysis of the dispersive signal demonstrates that quantum and tunneling capacitance changes must be included to describe the qubit-resonator interaction. Furthermore, a Fourier analysis of the interference pattern reveals a charge coherence time, T2 100 ps. Our results demonstrate charge coherent control and readout in a simple silicon transistor and open up the possibility to implement charge and spin qubits in existing CMOS technology.


Grechnev G.E.,Bverkin Institute For Low Temperature Physics And Engineering | Logosha A.V.,Bverkin Institute For Low Temperature Physics And Engineering | Panfilov A.S.,Bverkin Institute For Low Temperature Physics And Engineering | Shitsevalova N.Y.,Frantsevich Institute for Problems of Materials Science
Journal of Alloys and Compounds | Year: 2012

Experimental and theoretical studies of the pressure effects on magnetic properties and electronic structure of EuB6 and GdB6 compounds were carried out to shed light on the nature of their magnetic ordering. The magnetic susceptibility was measured under pressure up to 2 kbar at fixed temperatures of 78 and 300 K for the EuB6 and GdB 6 compounds, and also for the carbon doped EuB6, for comparison. The observed behavior of the paramagnetic Curie temperature Θ under pressure was analyzed within the RKKY-like approach based on the results of ab initio electronic structure calculations. © 2011 Elsevier B.V. All rights reserved.


Amaziane B.,University of Pau and Pays de l'Adour | Antontsev S.,University of Lisbon | Pankratov L.,University of Pau and Pays de l'Adour | Pankratov L.,Bverkin Institute For Low Temperature Physics And Engineering | And 2 more authors.
Multiscale Modeling and Simulation | Year: 2010

This paper is devoted to the homogenization of a coupled system of diffusionconvection equations in a domain with periodic microstructure, modeling the flow and transport of immiscible compressible, such as water-gas, fluids through porous media. The problem is formulated in terms of a nonlinear parabolic equation for the nonwetting phase pressure and a nonlinear degenerate parabolic diffusion-convection equation for the wetting saturation phase with rapidly oscillating porosity function and absolute permeability tensor. We obtain a nonlinear homogenized problem with effective coefficients which are computed via a cell problem. We rigorously justify this homogenization process for the problem by using two-scale convergence. In order to pass to the limit in nonlinear terms, we also obtain compactness results which are nontrivial due to the degeneracy of the system. © 2010 Society for Industrial and Applied Mathematics.


Amaziane B.,University of Pau and Pays de l'Adour | Antontsev S.,University of Lisbon | Pankratov L.,University of Pau and Pays de l'Adour | Pankratov L.,Bverkin Institute For Low Temperature Physics And Engineering
Nonlinear Analysis: Real World Applications | Year: 2012

A system of evolutionary partial differential equations (PDEs) describing the two-phase flow of immiscible fluids, such as watergas, through porous media is studied. In this formulation, the wetting and nonwetting phases are treated to be incompressible and compressible, respectively. This treatment is indeed necessary when a compressible nonwetting phase is subjected to compression during confinement. The system of PDEs consists of an evolution equation for the wetting-phase saturation and an evolution equation for the pressure in the nonwetting phase. This system is applied to the problem of unsaturated flows to assess gas migration and two-phase flow through engineered and geological barriers for a deep repository for radioactive waste. This paper is primarily concerned with the large time behavior of solutions of this system. Under some realistic assumptions on the data, we derive estimates of the speed of propagation of the gas by water in porous media. Namely, we establish estimates of time stabilization for the water saturation to a constant limit profile. The analysis is based on the energy methods whose main idea involves deriving and studying suitable ordinary differential inequalities. We show that the time of complete displacement of a gas by water may be at most infinite or finite depending essentially on the power parameters defining the capillary pressure and the relative permeabilities. This result is then illustrated with two examples in the context of gas migration in a deep nuclear waste repository. We consider Van Genuchten's and BrooksCorey's models for a two-phase watergas system. © 2012 Elsevier Ltd. All rights reserved.


Evstigneev M.P.,Kharkiv Polytechnic Institute | Buchelnikov A.S.,Kharkiv Polytechnic Institute | Voronin D.P.,Kharkiv Polytechnic Institute | Rubin Y.V.,Bverkin Institute For Low Temperature Physics And Engineering | And 3 more authors.
ChemPhysChem | Year: 2013

The contributions of various physical factors to the energetics of complexation of aromatic drug molecules with C60 fullerene are investigated in terms of the calculated magnitudes of equilibrium complexation constants and the components of the net Gibbs free energy. Models of complexation are developed taking into account the polydisperse nature of fullerene solutions in terms of the continuous or discrete (fractal) aggregation of C60 molecules. Analysis of the energetics has shown that stabilization of the ligand-fullerene complexes in aqueous solution is mainly determined by intermolecular van der Waals interactions and, to lesser extent, by hydrophobic interactions. The results provide a physicochemical basis for a potentially new biotechnological application of fullerenes as modulators of biological activity of aromatic drugs. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Amaziane B.,University of Pau and Pays de l'Adour | Pankratov L.,Bverkin Institute For Low Temperature Physics And Engineering | Piatnitski A.,Narvik University College | Piatnitski A.,RAS Lebedev Physical Institute
Networks and Heterogeneous Media | Year: 2010

The aim of the paper is to study the asymptotic behavior of solutions to a Neumann boundary value problem for a nonlinear elliptic equation with nonstandard growth condition of the form in a perforated domain Ωε ε being a small parameter that characterizes the microscopic length scale of the microstructure. Under the assumption that the functions p"(x) converge uniformly to a limit function p0;(x) and that p0 satisfy certain logarithmic uniform continuity condition, it is shown that uε converges, as ε → 0, to a solution of homogenized equation whose coefficients are calculated in terms of local energy characteristics of the domain Ωε This result is then illustrated with periodic and locally periodic examples. © American Institute of Mathematical Sciences.


Shevchenko S.N.,Bverkin Institute For Low Temperature Physics And Engineering | Shevchenko S.N.,RIKEN | Ashhab S.,RIKEN | Ashhab S.,University of Michigan | And 2 more authors.
Physics Reports | Year: 2010

A transition between energy levels at an avoided crossing is known as a Landau-Zener transition. When a two-level system (TLS) is subject to periodic driving with sufficiently large amplitude, a sequence of transitions occurs. The phase accumulated between transitions (commonly known as the Stückelberg phase) may result in constructive or destructive interference. Accordingly, the physical observables of the system exhibit periodic dependence on the various system parameters. This phenomenon is often referred to as Landau-Zener-Stückelberg (LZS) interferometry. Phenomena related to LZS interferometry occur in a variety of physical systems. In particular, recent experiments on LZS interferometry in superconducting TLSs (qubits) have demonstrated the potential for using this kind of interferometry as an effective tool for obtaining the parameters characterizing the TLS as well as its interaction with the control fields and with the environment. Furthermore, strong driving could allow for fast and reliable control of the quantum system. Here we review recent experimental results on LZS interferometry, and we present related theory. © 2010 Elsevier B.V.

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