The new two-stage scheme for deep laser cooling of ${}^{171} \mathbf{Y b}^{+}$ is suggested. This scheme apart from well-known approaches does not require application of magnetic field. The suggested approach opens up possibility for precise control of magnetic field for further progress in optical frequency standards and quantum computing.

We show the possibility of implementing a deep dissipative optical lattice for neutral atoms with a macroscopic period. The depth of the lattice can reach magnitudes comparable to the depth of the magneto-optical traps (MOT), while the presence of dissipative friction forces allows for trapping and cooling of atoms. The area of localization of trapped atoms reaches sub-millimeter size, and the number of atoms is comparable to the number trapped in MOT. As an example, we study lithium atoms for which the macroscopic period of the lattice $\Lambda=1.5$ cm. Such deep optical lattices with a macroscopic period open up possibility for developing effective methods for cooling and trapping neutral atoms without use of magnetic field as an alternative to MOT. This is important for developing compact systems based on cold atoms.

The work propose a scheme of deep laser cooling of ^171Yb^+. The cooling is based on the effect of electromagnetically induced transparency (EIT) in a polychromatic field with three frequency components are resonant to optical transitions of the ^2S_1/2→ ^2P_1/2 line. The deep cooling down to the ground motional state in a trap allows for a significant suppression of the second order Doppler shift in frequency standards. Moreover, there is no need to use a magnetic field, which is required for Doppler cooling of ^171Yb^+ in a field with two-frequency component. The cooling without use of magnetic field is important for deep suppression of quadratic Zeeman shifts of clock transitions from uncontrolled residual magnetic fields.

We propose a scheme of deep laser cooling of 171Yb+, which is based on the effect of electromagnetically induced transparency (EIT) in a polychromatic field with three frequency components resonant with optical transitions of the 2S1/2 -> 2P1/2 line. The deep cooling down to the ground motional state in a trap allows for a significant suppression of the second-order Doppler shift in the frequency standard. Moreover, in our scheme, there is no need to use a magnetic field, which is required for Doppler cooling of 171Yb+ in a field with a two frequency component. Cooling without the use of a magnetic field is important for the deep suppression of quadratic Zeeman shifts of clock transitions due to an uncontrolled residual magnetic field.

Subject of study. Three-dimensional solitons of the theory of self-induced transparency of laser pulses with a converging cylindrical wavefront and different transverse spatial profiles of the pulse field in 87Rb vapor (resonant transition D2, wavelength 780.24 nm) are studied. Aim of study. The aim is the experimental study of threedimensional solitons of self-induced transparency of laser pulses for the development of new device prototypes for resonant quantum microwave photonics using laser signal processing methods in the microwave region of the spectrum. Method. In the caustic of a focused beam of a laser pump pulse with a cylindrical wavefront, a transverse spatial profile of the electric field strength of a special shape is created. The computer-generated holograms developed by us can be used to create an arbitrary profile. Main results. The properties of a three-dimensional self-induced transparency soliton are studied for various detuning frequencies of the input pulse field with respect to atomic resonance. The maximum laser pulse power is 8.5 mW, the pulse duration is 4-5 ns, and the time resolution of the recording system is 27 ps. It is shown that the all-optical control of the carrier frequency of the input pulse determines the properties of the output pulse: compression of the pulse duration (generation of a strobe pulse), the value of the soliton delay in time, and the time shift of the carrier frequency of the soliton. Practical significance. The results obtained in this study of the properties of three-dimensional self-induced transparency solitons will serve as the basis for the development of prototypes of signal processing devices using low-power laser diodes. (c) 2023 Optica Publishing Group

Subject of study. The self-diffraction process of a resonant pulse in a dense extended resonant medium was studied for the first time to our knowledge. This process leads to an angular deflection of the output radiation and sequen-tial emission of a large series of N pulses with a variable area in the range (-3n, ... , 0, ... , 3n). The pulses are emitted from a small focusing region (0.1-1 mm) of the pump pulse in a dense extended resonant medium. The pulse wavelength corresponds to the resonant transition Ii2 87Rb (wavelength 780.24 nm). Aim of study. The non-linear effect of the self-diffraction of a laser pulse with a cylindrical wavefront is studied in an extended resonant medium of rubidium vapor to develop new resonant microwave photonics devices using laser signal-processing methods in the microwave spectrum. Method. A transverse spatial profile of the electric field strength of a special shape f (x) is created in the caustic of a focused beam of a laser pump pulse with a cylindrical wavefront. The pump pulse must have a converging (for example, cylindrical) wavefront. Computer-synthesized holograms developed by us are used to create an arbitrary f(x) profile. Main results. The effect of the self-diffraction of a pump pulse is studied. This is accompanied by the emission of a series of N coherent resonant pulses with different areas in the range (-3n, ... , 0, ... , 3n) from a short focusing region (0.1-1 mm) of a resonant laser pump pulse. The self -diffraction of the pump pulse resulted in 16 emitted pulses with different areas. The distribution of series pulses over the diffraction angle was observed in the angle range from -5 degrees to +4 degrees. The nonlinear generation of 0n-pulses was observed at some angles. The results verify the nonlinear generation of 0n-pulses over a short interaction length between light and a resonant medium for the first time to our knowledge. Practical significance. The obtained results on the effect of the self-diffraction of a resonant pulse with a transverse spatial profile f(x) will serve as a basis for the development of prototype devices for signal-processing problems using low-power laser diodes. (c) 2023 Optica Publishing Group

The results of the development of vertical-cavity surface emitting lasers based on Al $${}_{x}$$ Ga $${}_{1-x}$$ As and In $${}_{y}$$ Ga $${}_{1-y}$$ As solid solutions are presented. Developed lasers demonstrate stable single-mode operation at wavelengths of 794.9 and 894.6 nm, which offers the prospects of their applications in miniature quantum frequency standards based on $${}^{87}$$ Rb and $${}^{133}$$ Cs.

Олег Николаевич Крохин (к 90-летию со дня рождения), Багаев С.Н., Гаранин С.Г., Колачевский Н.Н., Конов В.И., Кульчин Ю.Н., Панченко В.Я., Попов Ю.М., Рыкованов Г.Н., Сергеев А.М., Сурис Р.А., Шалагин А.М., Щербаков И.А.

We report on a new project aimed for development of a transportable compact optical clock based on single 171 Yb + ion trapped in a ion Paul trap. The goal is to reach relative frequency instability level of 5E-16 at 24 hours averaging time.

Investigations are aimed at studying the blood circulation biomechanics, the physical mechanisms of the cardiovascular system transport function, and regularities of branching and dichotomic division and merging of blood flows at the level of bifurcations of large arterial blood vessels and microvessels. An analysis of created protacrylic casts of the heart and blood vessel cavities has revealed new anatomical peculiarities: funnel-shapedness of the configuration of heart and vessel chambers, tangentiality of atrial orifices and ventricular apertures, and tangentiality of branching of arterial blood vessels at the level of bifurcations. An original method of X-ray contrast cineangiocardiography has been developed. It has allowed, for the first time at the system level, to visualize the helical character of blood motion in the heart atriums and ventricles, arteries, and veins. In hydrodynamic investigations of the blood circulation system, the physical laws of conservation with a local dynamic approach for funnel-shaped canals were used. The performed fundamental investigations of the structural-functional organization of the cardiovascular system have allowed the authors to make a number of scientific discoveries. Briefly, their essence is in the following: The phenomenon of formation of a helical blood flow in the cardiovascular system shows new anatomical-functional principles in the greater and lesser circulations; The universal phenomenon of formation of a twisted flow of biological media in the canals of transport systems reveals the general physical mechanism in the organization and sustaining of a helical blood flow in the transport function of the cardiovascular system. This helical flow is created by a twisting wave excited in the channel walls by contraction of spirally oriented muscle and elastic elements; The property of a twisted liquid flow is to create a tractive force in funnel-shaped canals of variable circular section, and discloses the nature of arterial diastolic pressure due to the energy of rotational motion of a helical blood flow. Diastolic pressure is used to overcome the vascular resistance; The law of hemodynamics in arteries reveals a mathematical relation between the dynamic and kinematic characteristics of the helical blood flow; The law of branching of large arterial blood vessels establishes an unambiguous mathematical relation between the morphometric parameters of blood vessels, and the kinematic and dynamic parameters of the helical flow at the level of bifurcations of arteries and veins; The law of branching of blood microvessels reveals an unambiguous mathematical relation between the morphometric parameters of blood microvessels, the kinematic and dynamic parameters of the Poiseuille flow of blood in arterioles, capillaries, and venules. On the basis of the scientific discoveries, a new direction has been created. It makes it possible to develop new technologies of diagnostics, treatment, and prophylaxis in medical practice.

The paper discusses singling out of a slow deformation wave of pendulum type as an after-effect of a close-spaced strong earthquake. Based on the analysis of the laser records of the deformation process and aftershocks of several strong seismic events in the Baikal Rift Zone, the authors have detected the wanted slow deformation wave with the velocity range from 0.43 m/s to 1.76 m/s.

Spectral broadening of radiation emitted by a femtosecond Cr:forsterite laser in highly nonlinear fibers (HNLFs) has been investigated. Tapered HNLFs as well as fibers with constant dispersion and dispersion varying over the fiber length are investigated. The nonreciprocal effect of spectral broadening in fibers with varying dispersion is observed. A supercontinuum is obtained in the range from 990 to 2100 nm.

of the Russian Academy of Sciences (RAS), Director of the Solid State PhysicsDivision of theRASPNLebedev Physical Institute (FIAN), had his 70th birthday on 21 October 2007. Yurii Vasil'evich manifested his serious interest in physics while still a student. The paper that the student Yu VKopaev sent for publication was reviewed by a FIAN young research scientist L VKeldysh who wished to meet the juvenile author. Thismeeting and subsequent collaboration in research played a decisive role in the career of Yu V Kopaev. In 1964 Keldysh and Kopaev published the famous paper on the theory of insulator phase transitions (the Keldysh ± Kopaev model) in which they showed that the modified formalism of the BCS theory of superconductivity can be effectively used for a description of metal ± insulator phase transitions in solids. The phase transition arises in the model no matter how weak the interelectron interaction and, by analogy with the superconducting transition, can be interpreted as the Bose condensation of electron ± hole pairs (excitons). The insulator phase in the Keldysh ±Kopaev model was subsequently rechristened the `excitonic insulator' Ð the term that is now in general use. In fact, the Keldysh ±Kopaev excitonic insulator model became a standard way of describing interelectron correlations in the weak interaction limit. The importance of the exciton model of insulators follows largely from the fact that it describes (in a unified framework) an entire family of phase transitions with different types of symmetry of the ordered phase. The order parameter of the model characterizes the contribution of interelectron correlations to the self-consistent crystal potential. This potential has a complicated spin and phase structure that determines the type of ordering. Yu V Kopaev and coworkers showed that the excitonic insulator model describes a wide variety of experimentally observable states: charge and spin (band antiferromagnetism) density waves, weak ferromagnetism of collectivized electrons, and the ferroelectric state in nonionic crystals. Yu V Kopaev and his coworkers also studied various exotic states that arise in this model: states with spin and charge current (orbital antiferromagnetism). This last state is interesting in that under certain conditions it describes a qualitatively new type of ordered state in which the ordering parameter is the density of the toroidal dipole moment (toroidal moments are the third independent family, along with the electric and magnetic moments, of electromagnetic multipoles). It was also shown that microinhomogeneous toroidal orbital antiferromagnets can have anomalously high diamagnetism. Later, the ideas of Yu V Kopaev and his colleagues on ordered states with spontaneous currents were further developed in papers on strongly correlated states in connection with the problem of high-temperature superconductivity, where they are known as `flux phases'. In 1982 Yu V Kopaev, together with a team that submitted the completed project ``Prediction, detection and study of gapless semiconductors and exciton phases,'' received the USSR State Prize. A large series of papers written by Yu V Kopaev and coworkers is devoted to studying nonequilibrium phase transitions in semiconductors. In these papers the authors provide a reliable theoretical foundation to popular ideas of the analogy to laser generation phenomena and the phase transitions, and for the first time analyze them with mathematical rigor. Thus, Yu V Kopaev and his colleagues suggested and studied in detail the electron mechanism of laser annealing. The destruction of crystal structure connected with the formation of structural instability in response to the excitation of nonequilibrium charge carriers (nonequilibrium phase transition) is indeed observed in a number of semiconductors. This body of work, ``The discovery of the phenomenon of pulse-oriented crystallization in solids (laser annealing),'' received the USSR State Uspekhi Fizicheskikh Nauk 177 (11) 1251 ± 1252 (2007) DOI: 10.3367/UFNr.0177.200711g.1251 Translated by V I Kisin PERSONALIA PACS number: 01.60.+q

Single-frequency traveling-wave Nd:YAG and Yb:YAG lasers combining the functions of intracavity second harmonic generation and birefringent filter on one nonlinear crystal are discussed. The lasers were developed for spectroscopy and metrology applications. Output characteristics and spectral tuning ranges of the lasers are presented.

Евгений Борисович Александров (к семидесятилетию со дня рождения), Алферов Ж.И., Андреев А.Ф., Багаев С.Н., Белянин В.Б., Варшалович Д.А., Гинзбург В.Л., Забродский А.Г., Запасский В.С., Каплянский А.А., Перель В.И., Розанов Н.Н., Сурис Р.А.