Volume 193, Nº 4 (2023)
Reviews of topical problems
Laboratory modeling of jets from young stars using plasma focus facilities
Resumo
Jets from young stars are used as an example to review how laboratory modeling enables advancement in understanding the main physical processes responsible for the formation and stability of these amazing objects. The discussion focuses on the options for modeling jet emissions in a laboratory experiment at the PF-3 facility at the National Research Center Kurchatov Institute. Many properties of the flows obtained using this experimental setup are consistent with the main features of jets from young stars.
Uspehi fizičeskih nauk. 2023;193(4):345-381
345-381
Attosecond electromagnetic pulses: generation, measurement, and application. Attosecond metrology and spectroscopy
Resumo
When intense laser radiation interacts with matter, high-order harmonic generation (HHG) takes place; recent achievements in this area were reported by the authors in a review [V V Strelkov et al. Phys. Usp. 59 425 (2016)]. Under certain conditions, the phases of the harmonics can be synchronized in such a way that, adding up, the fields of the harmonics form attosecond ultraviolet (or X-ray) pulses. In this review, we address the generation of a train of attosecond pulses and a single attosecond pulse from a group of high-order harmonics. The problem of measuring the duration of attosecond pulses required both a serious modernization of the measurement methods known in femtosecond optics and the development of fundamentally new approaches. This review describes the main methods for measuring attosecond pulses that have been successfully demonstrated to date. Finally, the use of such pulses to probe the dynamics of electronic processes in matter and to control such processes at attosecond times is discussed.
Uspehi fizičeskih nauk. 2023;193(4):382-405
382-405
Photon correlations and features of nonclassical optical fields in a squeezed vacuum state
Resumo
We discuss the spatial and spectral properties of electromagnetic fields in a squeezed vacuum state and consider photon correlations in such fields. We concentrate on a bright squeezed vacuum with a large mean number of photons per mode and both spatial and frequency multimode structures. A theoretical approach based on the introduction of independent Schmidt modes and their photon operators is considered, which allows analytically correctly describing any characteristics of the squeezed field, including photon correlations, in good agreement with experiment. We present methods for controlling the mode content, degree of squeezing, and entanglement of photons of the generated squeezed light, including the scheme of a nonlinear interferometer; their advantages and applied prospects are analyzed. We discuss applied problems where squeezed nonclassical states are realized: the dispersion characteristics of media in the THz frequency range and high-precision detection of weak phase and angular perturbations based on correlations between photons.
Uspehi fizičeskih nauk. 2023;193(4):406-436
406-436
Theoretical and computational approaches to predicting the viscosity of liquids
Resumo
Predictive models for the shear viscosity of liquids and gases along with exact equations of state are of great practical importance for hydrodynamic modeling of processes occurring in nature, industrial plants, and machinery. We consider currently proposed theoretical, including atomistic modeling, and semi-empirical approaches to predicting the viscosity of liquids, gases, and their mixtures in a wide range of thermodynamic conditions. Viscosity models of homogeneous liquids in a thermodynamically stable state are described. The dynamics of supercooled and vitrescent liquids and dispersed systems (colloids, emulsions) remain beyond the scope of this review. We discuss the area of applicability of correlation methods for predicting viscosity and the accuracy of various methods in the pressure range up to 1 GPa. Application examples of various approaches for hydrocarbons—model oil and gas, fuel, and lubrication systems—are given.
Uspehi fizičeskih nauk. 2023;193(4):437-461
437-461
Physics news on the Internet: April 2023 (based on electronic preprints)
Uspehi fizičeskih nauk. 2023;193(4):462-462
462-462
Personalia
In memory of Semen Solomonovich Gershtein
Uspehi fizičeskih nauk. 2023;193(4):463-464
463-464