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卷 103, 编号 12 (2016)

Fields, Particles, and Nuclei

On the hyperfine structures of the ground state(s) in the 6Li and 7Li atoms

Frolov A.

摘要

The hyperfine structure of the ground 22S-states of the three-electron atoms and ions is investigated. By using our recent numerical values for the doublet electron density at the atomic nucleus, we determine the hyperfine structure of the ground (doublet) 22S-state(s) in the 6Li and 7Li atoms. Our predicted values (228.2058 and 803.5581 MHz, respectively) agree well with the experimental values 228.20528(8) MHz (6Li) and 803.50404(48) MHz (7Li [R.G. Schlecht and D.W. McColm, Phys. Rev. 142, 11 (1966)]). The hyperfine structures of a number of lithium isotopes with short lifetimes, including 8Li, 9Li, and 11Li atoms are also predicted. The same method is used to obtain the hyperfine structures of the three-electron 7Be+ and 9Be+ ions in their ground 22S-states. Finally, we conclude that our approach can be generalized to describe the hyperfine structure in the triplet n3S-states of the four-electron atoms and ions.

JETP Letters. 2016;103(12):739-742
pages 739-742 views

Scientific Summaries

Landau’s Nobel Prize in Physics

Larsson M., Balatsky A.

摘要

Work of Lev Landau had a profound impact on the physics in 20th century. Landau had created the paradigms that had framed the conversations on the outstanding problems in physics for decades. He had laid foundations for our understanding of quantum matter like superfluidity, superconductivity and the theory of Fermi liquid. Here we present some Nobel Archive data on the winning nomination that led to the Nobel Prize in Physics in 1962.

JETP Letters. 2016;103(12):795-798
pages 795-798 views

Condensed Matter

PT-symmetry breaking in resonant tunneling heterostructures

Gorbatsevich A., Shubin N.

摘要

We present fermionic model based on symmetric resonant tunneling heterostructure, which demonstrates spontaneous symmetry breaking in respect to combined operations of space inversion (P) and time reversal (T). PT-symmetry breaking manifests itself in resonance coalescence (collapse of resonances). We show that resonant energies are determined by eigenvalues of auxiliary pseudo-Hermitian PT-invariant Hamiltonian.

JETP Letters. 2016;103(12):769-773
pages 769-773 views

Contribution of interstitial defects and anharmonicity to the premelting increase in the heat capacity of single-crystal aluminum

Safonova E., Konchakov R., Mitrofanov Y., Kobelev N., Vinogradov A., Khonik V.

摘要

With the use of experimental data on the temperature dependence of the concentration of interstitial atoms, it has been shown within the interstitial theory that the premelting nonlinear increase in the heat capacity of aluminum can be caused by the intense generation of interstitial defects in a dumbbell configuration.

JETP Letters. 2016;103(12):765-768
pages 765-768 views

On the dispersion relation of magnetoplasmons in a planar graphene-based superlattice

Ratnikov P.

摘要

The dispersion relation for magnetoplasmons in a planar superlattice with periodically alternating regions of gapless and gapped modifications of graphene has been derived within the frame of the random-phase approximation. The contribution of virtual transitions between the lower electron miniband and the upper hole miniband to the polarization operator has been taken into account in addition to the contribution of virtual intra-miniband transitions.

JETP Letters. 2016;103(12):774-779
pages 774-779 views

Hamilton’s equations of motion of a vortex filament in the rotating Bose–Einstein condensate and their “soliton” solutions

Ruban V.

摘要

The equation of motion of a quantized vortex filament in a trapped Bose–Einstein condensate [A. A. Svidzinsky and A. L. Fetter, Phys. Rev. A 62, 063617 (2000)] has been generalized to the case of an arbitrary anharmonic anisotropic rotating trap and presented in the variational form. For condensate density profiles of the form ρ = f(x2 + y2 + ReΨ(x + iy)) in the presence of the plane of symmetry y = 0, the solutions x(z) describing stationary vortices of U and S types coming to the surface and solitary waves have been found in quadratures. Analogous three-dimensional configurations of the vortex filament uniformly moving along the z axis have also been found in strictly cylindrical geometry. The dependence of solutions on the form of the function f(q) has been analyzed.

JETP Letters. 2016;103(12):780-784
pages 780-784 views

Optics and Laser Physics

Features of the interaction of near-infrared laser radiation with Yb-doped dielectric nanoparticles

Ryabochkina P., Khrushchalina S., Kyashkin V., Vanetsev A., Gaitko O., Tabachkova N.

摘要

Experimental data have been presented to confirm the thermal nature of broadband visible radiation emitted from Yb3+- and Er3+-doped nanocrystalline particles of orthophosphates and orthophosphate hydrates irradiated by 972-nm near-infrared laser radiation. The mechanism of appearance of this radiation has been discussed.

JETP Letters. 2016;103(12):743-751
pages 743-751 views

Surface ablation оf aluminum and silicon by ultrashort laser pulses of variable width

Zayarny D., Ionin A., Kudryashov S., Makarov S., Kuchmizhak A., Vitrik O., Kulchin Y.

摘要

Single-shot thresholds of surface ablation of aluminum and silicon via spallative ablation by infrared (IR) and visible ultrashort laser pulses of variable width τlas (0.2–12 ps) have been measured by optical microscopy. For increasing laser pulse width τlas < 3 ps, a drastic (threefold) drop of the ablation threshold of aluminum has been observed for visible pulses compared to an almost negligible threshold variation for IR pulses. In contrast, the ablation threshold in silicon increases threefold with increasing τlas for IR pulses, while the corresponding thresholds for visible pulses remained almost constant. In aluminum, such a width-dependent decrease in ablation thresholds has been related to strongly diminished temperature gradients for pulse widths exceeding the characteristic electron-phonon thermalization time. In silicon, the observed increase in ablation thresholds has been ascribed to two-photon IR excitation, while in the visible range linear absorption of the material results in almost constant thresholds.

JETP Letters. 2016;103(12):752-755
pages 752-755 views

Inelastic processes and the reemission of attosecond and shorter electromagnetic pulses at the interaction with atoms

Makarov D., Matveev V.

摘要

Inelastic processes and the reemission of attosecond and shorter electromagnetic pulses by atoms have been considered within the analytical solution of the Schrödinger equation in the sudden perturbation approximation. A method of calculations with the exact inclusion of spatial inhomogeneity of the field of an ultrashort pulse and the momenta of photons in the reemission processes has been developed. The results have been presented in the form of analytical formulas. The probabilities of inelastic processes and spectra of reemission of ultrashort electromagnetic pulses by single-electron atoms have been calculated.

JETP Letters. 2016;103(12):756-760
pages 756-760 views

Plasma, Hydro- and Gas Dynamics

Phenomenon of apokamp discharge

Sosnin E., Skakun V., Panarin V., Pechenitsin D., Tarasenko V., Baksht E.

摘要

A new phenomenon has been discovered where a bend of a plasma channel becomes of a source of one or several diffuse jets that have a length (at a given voltage) up to 4–6 cm and are directed across the plasma channel at a pulse-periodic spark discharge in air under normal conditions. The phenomenon is called apokamp discharge (apokamp). The spectrum of radiation of the apokamp includes primarily the bands of electron-vibrational transitions of the second positive system of molecular nitrogen. The conditions of the formation of apokamp have been experimentally revealed and it has been established that it consists of plasma bunches moving from the plasma channel at each pulse at a velocity of about 220 km/s.

JETP Letters. 2016;103(12):761-764
pages 761-764 views

Quantum Informatics

On protection against a bright-pulse attack in the two-pass quantum cryptography system

Balygin K., Klimov A., Korol’kov A., Kulik S., Molotkov S.

摘要

The security of keys in quantum cryptography systems, in contrast to mathematical cryptographic algorithms, is guaranteed by fundamental quantum-mechanical laws. However, the cryptographic resistance of such systems, which are distributed physical devices, fundamentally depends on the method of their implementation and particularly on the calibration and control of critical parameters. The most important parameter is the number of photons in quasi-single-photon information states in a communication channel. The sensitivity to a bright-pulse attack has been demonstrated in an explicit form for a number of systems. A method guaranteeing the resistance to such attacks has been proposed and implemented. Furthermore, the relation of physical observables used and obtained at the control of quantum states to the length of final secret keys has been obtained for the first time.

JETP Letters. 2016;103(12):785-791
pages 785-791 views

Miscellaneous

On the response time of plasmonic terahertz detectors

Muravev V., Solov’ev V., Fortunatov A., Tsydynzhapov G., Kukushkin I.

摘要

The response time of a plasmonic terahertz detector is investigated using two independent experimental techniques relying on time-resolved and heterodyne measurements, respectively. Both methods demonstrate that the detector response time does not exceed 110 ps. The results obtained suggest that the designed terahertz detector can be used as a component of high-speed telecommunication systems of a new generation.

JETP Letters. 2016;103(12):792-794
pages 792-794 views

Discussion

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