JETP Letters最新文献

The influence of ion thermal motion on the Stark broadening of spectral lines in plasmas is investigated within the frequency fluctuation method (FFM). The method for the consistent calculation of the jumping frequency, which is the main FFM parameter, is suggested on the basis of the S. Chandrasekhar and J. von Neumann stochastic theory. The calculations of the neutral hydrogen spectra in plasmas are presented. These results are compared with the experimental data. The spectra of the Ar dopant in the deuterium plasma are calculated taking into account ion thermal motion. The effect of ion thermal motion on the dip in the He_β spectral line of the He-like Ar ion is shown. The calculations of the He_β lineshape of the He-like Ti ion are compared with experimental data.

The applicability of the method for measuring the probe absorption and gain spectra in a system of quantum emitters excited by a resonant driving field for studying cooperative photoluminescence is considered. The gain and attenuation of a probe signal in the system of two quantum emitters with the dipole–dipole interaction have been calculated for the conditions of observing the cooperative photoluminescence of a pair of impurity molecules described in the literature and close to them. The resulting dependences demonstrate the structure of excited collective molecular states, which can be used to reconstruct the positions of molecules in a matrix and to determine the difference in their photophysical properties. Thus, the probe absorption and gain spectra can be used to analyze the photoluminescence of quantum-entangled particles and to transform light signals.

A surprisingly large number of galaxies with masses of ~10⁹–10¹⁰({{M}_{ odot }}) at redshifts of (z geqslant 9) are discovered with the James Webb Space Telescope. A possible explanation for the increase in the mass function can be the presence of a local maximum (bump) in the power spectrum of density perturbations on the corresponding scale. In this paper, it is shown that simultaneously with the growth of the mass function, galaxies from the bump region must have a higher density (compactness) compared to cosmological models without a bump. These more compact galaxies have been partially included in larger galaxies and have been subjected to tidal gravitational disruption. They have been less destructed than “ordinary” galaxies of the same mass, and some of them could survive to z = 0 and persist on the periphery of some galaxies. The formation and evolution of compact halos in a cube with a volume of (47 Mpc)³ with (1024)³ dark matter particles in the redshift range from 120 to 0 have been numerically simulated and observational implications of the presence of such galaxies in the current Universe have been discussed.

We calculate electronic structure and spin susceptibility dependencies on doping within the framework of a cluster perturbation theory for strongly correlated electronic systems. The change in the susceptibility with increasing doping is qualitatively consistent with the experimental data on resonant inelastic X-ray scattering and inelastic neutron scattering, as well as with the results of the calculations within the quantum Monte Carlo method.

We present the study of the antibacterial properties of ZnO/CuO films, activated by LED lamp light with an emission spectrum close to that of natural sunlight, on an example of antibiotic-resistant S. aureus bacterial culture. The antibacterial properties of films with photoinduced electroporation lead to the emergence of a potential difference between semiconductor n-type ZnO and p-type CuO nanoparticles with a local increase in field intensity to a value ( sim {kern 1pt} 1 times {{10}^{4}}) V/cm, sufficient for irreversible electroporation to occur. Exposure leads to a decrease in bacterial contamination from the value (8 times {{10}^{8}}) CFU/mL to 0. Raman spectra before and after exposure were analyzed by calculating spectral peak parameters corresponding to molecular vibrations in nucleic acids, cell membranes, and proteins. The disappearance or degradation of peaks illustrating vibrations of A, G in nucleic acids, disruption of the secondary structure of proteins and the appearance of disordered forms of amide I were detected, as well as the emerging disorder of lipid chains in the membrane and the destruction of N-acetylmuramic acid and N-acetylglucosamine, which are part of the gram-positive microorganisms’ cell membrane, therefore indicating the destruction of the cell wall and irreversible destruction of the internal structure of the cells.

The appearance of the population difference in the ground state of the (Lambda )-system due to the spontaneous decay of the upper level into lower ones is considered. The resulting asymmetry of the coherent population trapping resonance is shown to lead to a frequency shift of the quadrature signal, which nonlinearly depends on the optical field intensity. In this case, this contribution is not suppressed due to the use of high modulation frequencies compared to the relaxation rate of ground state polarization (analogue of the Pound–Drever–Hall technique). A significant smallness of this shift when using a binary mixture of noble buffer gases is discussed.

Interest in hybrid quasi-one-dimensional systems with an inner semiconducting part coated with a superconductor (the so-called core/shell structure) has been grown in the last decade. Materials with a strong spin‒orbit coupling and a large g-factor (InAs, InSb) are chosen as semiconductors. Due to the proximity effect, such objects can be considered as superconducting wires, where the existence of Majorana states has been predicted. This review briefly summarizes the current experimental studies aimed at the detection of Majorana quasiparticle excitations in superconducting wires. Furthermore, prospects of using the interference geometry of devices including such wires are discussed. In particular, the coherent transport in a spatially inhomogeneous one-dimensional normal metal/superconductor/normal metal system, where normal metal wires serve as arms of an interference device, which interact with a normal metal contact, has been analyzed theoretically. It has been found that responses of Majorana and Andreev low-energy excitations of the device can be distinguished.

A method to measure the correlation function of a biphoton field, which does not require single-photon detectors and photocount coincidence schemes, has been proposed and experimentally approved. It is based on the statistical analysis of current data from analog detectors. On an example of the operation of a scheme with analog photomultiplier tubes in the signal and idler channels of degenerate parametric down conversion, it has been shown that this new approach allows one to obtain correlation function values coinciding with the results of the standard photon counting technique. It has been shown how the absolute values of photon numbers and radiation power in the signal channel of the down conversion scheme are determined from the measured correlation function. Analog detection can expand the spectral and dynamic ranges of electromagnetic radiation for the application of quantum optic technologies. A method for the reference-free measurement of the spectral sensitivity of an analog photosensor module has been demonstrated as the first example of application.

We experimentally study magnetization reversal curves for MnTe single crystals, which is the altermagnetic candidate. Above 85 K temperature, we confirm the antiferromagnetic behavior of magnetization M, which is known for α-MnTe. Below 85 K, we observe anomalous low-field magnetization behavior, which is accompanied by the sophisticated (M(alpha )) angle dependence with beating pattern as the interplay between (M(alpha )) maxima and minima: in low fields, (M(alpha )) shows ferromagnetic-like 180° periodicity, while at high magnetic fields, the periodicity is changed to the 90° one. This angle dependence is the most striking result of our experiment, while it can not be expected for standard magnetic systems. In contrast, in altermagnets, symmetry allows ferromagnetic behavior only due to the spin–orbit coupling. Thus, we claim that our experiment shows the effect of weak spin–orbit coupling in MnTe, with crossover from relativistic to non-relativistic net magnetization, and, therefore, we experimentally confirm altermagnetism in MnTe.

The generation of spectral components sensitive to the carrier-envelope phase of a laser pulse in a thin zinc selenide film has been experimentally demonstrated and confirmed by a numerical simulation. A pump–probe scheme has been implemented so that a pump pulse with a duration of about 1.5 field cycles, a central wavelength of 1.7 μm, and a stabilized carrier-envelope phase induces photoionization in a thin zinc selenide film. The probe pulse is scattered by the plasma, generating new phase-sensitive spectral components at the edges of its spectrum. The theoretical analysis has confirmed plasma nonlinearity as a mechanism for generating these components. The observed effect can be used to characterize the carrier-envelope phase of ultrashort pulses during the generation of high-order harmonics and sequences of attosecond pulses.