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K.-U. Neumann F. Kusmartsev H.-J. Lauter O. Schärpf T.J. Smith K.R.A. Ziebeck 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(1):5-9
A polarized neutron scattering investigation of the flux line lattice in the type-II superconductor niobium is reported. A
modulation of the nuclear lattice has been detected, and the magnitude of the first Fourier component of the lattice distortion
established relative to the magnitude of the magnetic scattering. This constitutes the first experimental observation of lattice
distortions due to the presence of magnetic flux lines within the bulk of a type-II superconductor. Using a simple microscopic
model the lattice distortion in niobium is estimated. A new mechanism is suggested for the coupling of the flux line lattice
to the crystallographic lattice. The experimental technique opens up the possibility of investigating the microscopic mechanism
of flux line - nuclear lattice interactions, in particular the pinning of flux lines within the bulk of a type-II superconductor.
Received: 8 August 1997 / Accepted: 16 October 1997 相似文献
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M. S.?GarelliEmail author F. V.?Kusmartsev 《The European Physical Journal B - Condensed Matter and Complex Systems》2005,48(2):199-206
We have studied a system composed by two endohedral fullerene
molecules. We have found that this system can be used as good candidate for the realization of quantum gates. Each of these
molecules encapsules an atom carrying a
spin, therefore they interact through the spin dipole interaction.
We show that a phase gate can be realized if we apply static and time dependent magnetic fields on each encased spin. We have
evaluated the operational time of a π-phase gate, which is of the order of ns. We made a comparison between the theoretical
estimation of the gate time and the
experimental decoherence time for each spin. The comparison shows that the spin relaxation time is much larger than the π-gate
operational time. Therefore, this indicates that, during the
decoherence time, it is possible to perform some thousands of quantum computational operations. Moreover, through the study
of concurrence, we get very good results for the entanglement degree of the two-qubit system. This finding opens a new avenue
for the realization of quantum computers. 相似文献
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Using the linear fractional transformation, which connects the effective conductivities \(\hat \sigma _e \) of isotropic two-phase systems with and without magnetic field, explicit approximate expressions for \(\hat \sigma _e \) in a magnetic field are obtained. They allow one to describe \(\hat \sigma _e \) of various inhomogeneous media at arbitrary phase concentrations x and magnetic fields. The x-dependence plots of \(\hat \sigma _e \) at some values of inhomogeneity and magnetic field are constructed. Their behavior is qualitatively compatible with the existing experimental data. The obtained results are applicable to different two-phase systems (regular and irregular as well as random), which satisfy the symmetry and self-duality conditions, and admit direct experimental checking. 相似文献
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Satpal Matharu Feodor V. Kusmartsev Alexander G. Balanov 《The European physical journal. Special topics》2013,222(10):2559-2570
We theoretically show that two semiconductor superlattices arranged on the same substrate and coupled with the same resistive load can be used for a generation of high-frequency periodic and quasiperiodic signals. Each superlattice involved is capable to generate current oscillations associated with drift of domains of high charge concentration. However, the coupling with the common load can eventually lead to synchronization of the current oscillations in the interacting superlattices. We reveal how synchronization depends on detuning between devices and the resistance of the common load, and discuss the effects of coupling and detuning on the high-frequency power output from the system. 相似文献
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We peruse various anomalous physical responses of the cubic (ferromagnetic SrRuO3 and paramagnetic CaRuO3) ruthenates, such as fractional power-law conductivity, anomalous Raman line shapes, and Hall currents. We show how these exciting power-law observations are naturally described within a new, local (orbital) non-Fermi-liquid state arising from strong, multiorbital Coulomb interactions. Introducing a multiorbital, correlated model treated within the dynamical mean-field theory, we also find two distinct relaxation rates for relaxation of transport in complete agreement with experiment. 相似文献
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Gulevich DR Kusmartsev FV Savel'ev S Yampol'skii VA Nori F 《Physical review letters》2008,101(12):127002
We predict a new class of excitations propagating along a Josephson vortex in two-dimensional Josephson junctions. These excitations are associated with the distortion of a Josephson vortex line and have an analogy with shear waves in solid mechanics. Their shapes can have an arbitrary profile, which is retained when propagating. We derive a universal analytical expression for the energy of arbitrary shape excitations, investigate their influence on the dynamics of a vortex line, and discuss conditions where such excitations can be created. Finally, we show that such excitations play the role of a clock for a relativistically moving Josephson vortex and suggest an experiment to measure a time dilation effect analogous to that in special relativity. 相似文献
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V. A. Maksimenko V. V. Makarov A. A. Koronovskii A. E. Hramov R. Venckevičius G. Valušis A. G. Balanov F. V. Kusmartsev K. N. Alekseev 《JETP Letters》2016,103(7):465-470
A very simple model describing steady-state electron transport along a quantum superlattice of a finite length taking into account an arbitrary electrical characteristic of the injecting contact is considered. In the singleminiband approximation, exact formulas for the spatial distribution of the electric field in the superlattice are derived for different types of contact. Conditions under which the field is uniform are identified. Analytical expressions for the current–voltage characteristics are obtained. In the context of the developed theory, the possibility of attaining uniform-field conditions in a diode structure with a natural silicon-carbide superlattice is discussed. 相似文献