arXiv subjects

A. S. Pazgalev

Publications and source records attributed to A. S. Pazgalev.

8 recordsLinked to original sources

arXiv2025

Linear dichroism signals due to the alignment in the ground state of hydrogen-like atoms and their inversion in a single-beam optical pumping scheme

The results of a study of the dynamics of atomic moments alignment in cesium under optical pumping by linearly polarized resonant light in ultra-weak magnetic field are presented. It is shown that there are alignment components whose relaxation does not depend on spin-exchange broadening. The effect of suppression of spin-exchange relaxation in zero magnetic fields is detected, which is similar in its manifestations to the SERF (Spin-Exchange Relaxation Free) effect observed in orientation signals. This observation is interesting from the standpoint of general theory, since the law of conservation of angular momentum responsible for maintaining orientation in the SERF mode should not guarantee the preservation of alignment under the same conditions. A comparison with theoretically calculated parameters of SERF resonances in orientation is given. A qualitative explanation of the observed effect is presented.

physics.atom-ph↗

arXiv2024

A method of laser frequency stabilization based on the effect of linear dichroism in alkali metal vapors in a modulated transverse magnetic field

We present a method of laser frequency stabilization based on the linear dichroism signal in a transverse magnetic field. The method is similar to the DAVLL (Dichroic Atomic Vapor Laser Lock) method. It differs from DAVLL and from its existing modifications primarily by the fact that it uses signal of linearly polarized light caused by alignment, rather than circular refraction caused by orientation, and therefore allows to obtain error signals at the magnetic field modulation frequency (or its second harmonic) by extremely simple means. The method does not require the strong magnetic fields or careful shielding of the working cell. The method allows the laser frequency to be stabilized in the vicinity of the low-frequency transition in the D1 line of Cs. Although the absorption line in a gas-filled cell is typically gigahertz wide, the achievable resolution, limited by the signal-to-noise ratio of photon shot noise, can reach tens of kilohertz in one hertz bandwidth.

physics.atom-ph↗

arXiv2023

Optically driven spin-alignment precession

The effect of optically driven spin precession discovered by Bell and Bloom [W. E. Bell and A. L. Bloom, Phys. Rev. Lett. 6, 280 (1961)] is widely used nowadays as a basis for numerous experiments in fundamental physics and for diverse applications. In this paper we consider a much less popular version of the light-induced spin precession that does not imply coherent precession of the spin-system magnetization and is excited by linearly (rather than circularly) polarized light. Pump-probe measurements performed on the D2 line of cesium vapor show that the magnitude of the signal of the optically driven spin-alignment precession, in "vacuum" cells (with no buffer gas) is close to that of classical spin-orientation precession. In the presence of buffer gas, however, the signal of spin-alignment precession appears to be strongly suppressed. The discovered effect is ascribed to spin mixing of excited states of cesium atoms in the cycle of optical pumping.

physics.atom-ph↗

arXiv2023

Ultimate parameters of an all-optical MX resonance in Cs in ultra-weak magnetic field

We present the results of studying the parameters of the magnetic MX resonance in an all-optical sensor built according to the two-beam Bell-Bloom scheme in nonzero ultra-weak magnetic fields in which the effects of spin-exchange broadening suppression are partially manifested. We report on the features of the resonance under these conditions. We also optimize the resonance parameters to achieve maximum sensitivity in magnetoencephalographic sensors. We demonstrate an improvement in the ultimate achievable sensitivity of an all-optical MX sensor by a factor of four or more, which in our experiment corresponds to a decrease from 13 to 3 fT/Hz1/2 in a volume of 0.13 cm3. We also report the effect of incomplete suppression of spin-exchange broadening under conditions of strong transverse modulated optical pumping, and propose a semi-empirical model to describe it.

physics.optics↗

arXiv2021

Single-beam all-optical non-zero field magnetometric sensor for magnetoencephalography applications

We present a method for measuring the magnetic field that allows hyperfine and Zeeman optical pumping, excitation and detection of magnetic resonance by means of a single laser beam with time-modulated ellipticity. This improvement allows us to significantly simplify the Bell-Bloom magnetometric scheme, while retaining its sensitivity. The method does not require the use of radio frequency fields, which is essential when creating arrays of sensors. The results of experimental studies demonstrate the efficiency of the proposed method and its potential applicability in most challenging magnetoencephalographic tasks.

physics.optics↗

arXiv2019

Isotope shift of nuclear magnetic resonances in 129Xe and 131Xe caused by spin-exchange pumping by alkali metal atoms

The effect of isotope shifts of nuclear magnetic resonance (NMR) frequency in xenon isotopes 129Xe and 131Xe polarized by optically-oriented alkali metal atoms is not only of fundamental interest, but also of practical significance since it is the main factor limiting the accuracy of a whole class of prospective navigation and metrological devices. We have studied the parametric dependences of the isotope shift and have shown that this effect is largely due to incomplete averaging of a inhomogeneous local magnetic field by two xenon isotopes. A numerical model has been derived, which qualitatively describes the effect of isotope frequency shift and provides a good quantitative agreement with the experiment.

physics.atom-ph↗

arXiv2008

An Improved Neutron Electric Dipole Moment Experiment

A new measurement of the neutron EDM, using Ramsey's method of separated oscillatory fields, is in preparation at the new high intensity source of ultra-cold neutrons (UCN) at the Paul Scherrer Institute, Villigen, Switzerland (PSI). The existence of a non-zero nEDM would violate both parity and time reversal symmetry and, given the CPT theorem, might lead to a discovery of new CP violating mechanisms. Already the current upper limit for the nEDM (|d_n|<2.9E-26 e.cm) constrains some extensions of the Standard Model. The new experiment aims at a two orders of magnitude reduction of the experimental uncertainty, to be achieved mainly by (1) the higher UCN flux provided by the new PSI source, (2) better magnetic field control with improved magnetometry and (3) a double chamber configuration with opposite electric field directions. The first stage of the experiment will use an upgrade of the RAL/Sussex/ILL group's apparatus (which has produced the current best result) moved from Institut Laue-Langevin to PSI. The final accuracy will be achieved in a further step with a new spectrometer, presently in the design phase.

nucl-ex↗

arXiv2004

Comparison of discharge lamp and laser pumped cesium magnetometers

We have performed a comparison of laser (LsOPM) and lamp (LpOPM) pumped cesium vapor magnetometers. Although the LsOPM operated 50% above its shot-noise limit we found an intrinsic sensitivity of 15 fT/\sqrt{Hz} and 25 fT/\sqrt{Hz} for the LsOPM and LpOPM respectively. Two modes of operation, viz.,the phase-stabilized and the self-oscillating mode were investigated and found to yield a similar performance. We have compared the performance of the LsOPM and the LpOPM directly by simultaneous measurements of field fluctuations of a 2 microtesla magnetic field inside a multilayer magnetic shield and have used one of the magnetometers for an active field stabilization. In the stabilized mode we found a gradient instability of 25 fT within an integration time of 100 s, which represents an upper limit of the long-term stability of the magnetometers.

physics.atom-ph↗