arXiv subjects

D. V. Makarov

Publications and source records attributed to D. V. Makarov.

15 recordsLinked to original sources

arXiv2026

Influence of pump size on pattern formation in exciton-polaritonic Bose-Einstein condensates in the non-Markovian regime

Dynamics of exciton-polaritonic condensate under incoherent pumping is studied using the non-Markovian stochastic Gross-Pitaevskii equation with the pseudo-differential dispersion term. This term corresponds to the lower energy branch of polaritons. It is shown that an increasing of the pumping spot area leads to the appearance of various spatial structures whose properties depend on the duration of the dynamical memory. In the regime of short memory time, condensate can form an extended state that spans outside the pumping area. We conclude that onset of such extended states is related to the specific form of the dispersion term causing the ``traffic jam'' effect. The case of long memory time corresponds to enhanced condensate formation, when increasing of the pumping area leads to appearance of angular condensate structures which partially suppress emission of matter waves from the pumping area.

cond-mat.quant-gas↗

arXiv2025

Phase alignment in a lattice of exciton-polaritonic Bose-Einstein condensates

Dynamics of exciton-polariton Bose-Einstein condensate is examined by means of the stochastic Gross-Pitaevskii equation including non-Markovian coupling to the excitonic reservoir. Attention is concentrated on properties of the condensate lattice created by laser beams providing incoherent pumping of the reservoir. It is shown that phase ordering of the lattice depends on temperature. The crossover between the in-phase (``ferromagnetic'') and the checkboard (``antiferromagnetic'') orders is accompanied by variation of the steady-state condensate density. Also it is shown that the condensate lattices can retain ordered pattern for temperatures which are much higher than the critical temperature of a single spot, probably due to suppression of the modulational instability.

cond-mat.quant-gas↗

arXiv2022

Non-Markovian stochastic Gross-Pitaevskii equation for the exciton-polariton Bose-Einstein condensate

In this paper, a non-Markovian Gross-Pitaevskii equation is proposed to describe the formation of a condensate in an exciton-polariton system under incoherent pumping. By introducing spatially delta-correlated noise terms, we observe a transition from a spatially ordered phase to a disordered one as the temperature increases. In course of this process, the population of the condensate is significantly reduced. Irregularly located separate dense spots of condensate above the transition temperature are revealed. Using the Gabor transform, it is shown that, with increasing temperature, the condensate decoheres, that is accompanied by the transition from narrowband to broadband spectral density.

cond-mat.quant-gas↗

arXiv2016

Zitterbewegung with spin-orbit coupled ultracold atoms in a fluctuating optical lattice

Dynamics of non-interacting ultracold atoms with artificial spin-orbit coupling is considered. Spin-orbit coupling is created using two moving optical lattices with orthogonal polarizations. Our main goal is to study influence of lattice noise on Rabi oscillations. Special attention is paid to the phenomenon of the Zitterbewegung being trembling motion caused by Rabi transitions between states with different velocities. Phase and amplitude fluctuations of lattices are modelled by means of the two-dimensional stochastic Ornstein-Uhlenbeck process, also known as harmonic noise. In the the noiseless case the problem is solved analytically in terms of the momentum representation. It is shown that lattice noise significantly extends duration of the Zitterbewegung as compared to the noiseless case. This effect originates from noise-induced decoherence of Rabi oscillations.

cond-mat.quant-gas↗

arXiv2014

Recovery of ordered periodic orbits with increasing wavelength for sound propagation in a range-dependent waveguide

We consider sound wave propagation in a range-periodic acoustic waveguide in the deep ocean. It is demonstrated that vertical oscillations of a sound-speed perturbation, induced by ocean internal waves, influence near-axial rays in a resonant way, producing ray chaos and forming a wide chaotic sea in the underlying phase space. We study interplay between chaotic ray dynamics and wave motion with signal frequencies of 50-100 Hz. The Floquet modes of the waveguide are calculated and visualized by means of the Husimi plots. Despite of irregular phase space distribution of periodic orbits, the Husimi plots display the presence of ordered peaks within the chaotic sea. These peaks, not being supported by certain periodic orbits, draw the specific "chainlike" pattern, reminiscent of KAM resonance. The link between the peaks and KAM resonance is confirmed by ray calculations with lower amplitude of the sound-speed perturbation, when the periodic orbits are well-ordered. We associate occurrence of the peaks with the recovery of ordered periodic orbits, corresponding to KAM resonance, due to suppressing of wavefield sensitivity to small-scale features of the sound-speed profile.

nlin.CD↗

arXiv2013

Quantum ratchet driven by broadband perturbation

Motion of an atomic ensemble trapped into a deep optical lattice is considered. We propose a novel approach to construct an atomic ratchet by superimposing two additional lattices whose amplitudes are small and subjected to broadband modulation. The broadband modulation is modeled by means of harmonic noise. Directed atomic transport occurs with the properly chosen phase shift between the signals modulating the amplitudes of the additional lattices. It is shown that efficiency of the ratchet depends non-monotonously on the parameter determining the spectral width of modulating signals.

nlin.CD↗

arXiv2013

Control of atomic transport using autoresonance

Dynamics of an atomic wavepacket in an optical superlattice is considered. We propose a simple scheme of wavepacket localization near the minima of the optical potential. In our approach, a wavelike perturbation caused by an additional lattice induces classical resonance which traps an atomic cloud. Adiabatic phase modulation of the perturbation slowly shifts resonance zone in phase space to the range of lower energies, retaining trapped atoms inside. This phenomenon is a kind of autoresonance. Quantum computations agree well with classical modelling.

nlin.CD↗

arXiv2013

Landau-Zener tunneling in 2D periodic structures in the presence of a gauge field II: Electric breakdown

We analyze dynamics of a quantum particle in a square lattice in the Hall configuration beyond the single-band approximation. For vanishing gauge (magnetic) field this dynamics is defined by the inter-band Landau-Zener tunneling, which is responsible for the phenomenon known as the electric breakdown. We show that in the presence of a gauge field this phenomenon is absent, at least, in its common sense. Instead, the Landau-Zener tunneling leads to appearance of a finite current which flows in the direction orthogonal to the vector of a potential (electric) field.

cond-mat.mes-hall↗

arXiv2012

Interplay between dipole and quadrupole modes of field influence in liquid-crystalline suspensions of ferromagnetic particles

In the framework of continuum theory we study orientational transitions induced by electric and magnetic fields in ferronematics, i.e., in liquid-crystalline suspensions of ferromagnetic particles. We have shown that in a certain electric field range the magnetic field can induce a sequence of re-entrant orientational transitions in ferronematic layer: nonuniform phase --- uniform phase --- nonuniform phase. This phenomenon is caused by the interplay between the dipole (ferromagnetic) and quadrupole (dielectric and diamagnetic) mechanisms of the field influence on a ferronematic structure. We have found that these re-entrant Freedericksz transitions exhibit tricritical behavior, i.e., they can be of the first or the second order. The character of the transitions depends on a degree of redistribution of magnetic admixture in the sample exposed to uniform magnetic field (magnetic segregation). We demonstrate how electric and magnetic fields can change the order of orientational transitions in ferronematics. We show that electric Freedericksz transitions in ferronematics subjected to magnetic field have no re-entrant nature. Tricritical segregation parameters for the transitions induced by electric or magnetic fields are obtained analytically. We demonstrate the re-entrant behavior of ferronematic by numerical simulations of the magnetization and optical phase lag.

cond-mat.soft↗

arXiv2012

Study of wave chaos in a randomly-inhomogeneous oceanic acoustic waveguide: spectral analysis of the finite-range evolution operator

The proplem of sound propagation in an oceanic waveguide is considered. Scattering on random inhomogeneity of the waveguide leads to wave chaos. Chaos reveals itself in spectral properties of the finite-range evolution operator (FREO). FREO describes transformation of a wavefield in course of propagation along a finite segment of a waveguide. We study transition to chaos by tracking variations in spectral statistics with increasing length of the segment. Analysis of the FREO is accompanied with ray calculations using the one-step Poincaré map which is the classical counterpart of the FREO. Underwater sound channel in the Sea of Japan is taken for an example. Several methods of spectral analysis are utilized. In particular, we approximate level spacing statistics by means of the Berry-Robnik and Brody distributions, explore the spectrum using the procedure elaborated by A. Relano with coworkers (Relano et al, Phys. Rev. Lett., 2002; Relano, Phys. Rev. Lett., 2008), and analyze modal expansions of the eigenfunctions. We show that the analysis of FREO eigenfunctions is more informative than the analysis of eigenvalue statistics. It is found that near-axial sound propagation in the Sea of Japan preserves stability even over distances of hundreds kilometers. This phenomenon is associated with the presence of a shearless torus in the classical phase space. Increasing of acoustic wavelength degrades scattering, resulting in recovery of localization near periodic orbits of the one-step Poincaré map. Relying upon the formal analogy between wave and quantum chaos, we suggest that the concept of FREO, supported by classical calculations via the one-step Poincaré map, can be efficiently applied for studying chaos-induced decoherence in quantum systems.

nlin.CD↗

arXiv2010

Level spacing statistics in a randomly-inhomogeneous acoustic waveguide

Dynamics of a randomly-perturbed quantum system with 3/2-degrees of freedom is considered. We introduce a transfer operator being the quantum analogue of the specific Poincaré map. This map was proposed in (Makarov, Uleysky, J. Phys. A: Math. Gen., 2006) for exploring domains of finite-time stability, which survive under random excitation. Our attention is concentrated on level spacing distribution of the transfer operator, averaged over ensemble of realizations. The problem of sound propagation in an oceanic waveguide is considered as an example. For the acoustic frequency of 200 Hz, level spacing distribution undergoes the crossover from Poissonian to Wigner-like statistics with increasing time, as it is consistent with classical predictions via the specific Poincaré map. For the frequency of 600 Hz, the level spacing statistics becomes non-universal due to large number of nearly-degenerate levels whose contribution grows with time. Occurrence of nearly-degenerate levels is attributed to bifurcations of classical periodic orbits, caused by fast spatial oscillations of the random perturbation.

nlin.CD↗

arXiv2007

Giant acceleration in slow-fast space-periodic Hamiltonian systems

Motion of an ensemble of particles in a space-periodic potential well with a weak wave-like perturbation imposed is considered. We found that slow oscillations of wavenumber of the perturbation lead to occurrence of directed particle current. This current is amplifying with time due to giant acceleration of some particles. It is shown that giant acceleration is linked with the existence of resonant channels in phase space.

nlin.CD↗

arXiv2005

Sensitivity of ray dynamics in an underwater sound channel to vertical scale of longitudinal sound-speed variations

We investigate sound ray propagation in a range-dependent underwater acoustic waveguide. Our attention is focused on sensitivity of ray dynamics to the vertical structure of a sound-speed perturbation induced by ocean internal waves. Two models of longitudinal sound-speed variations are considered: a periodic inhomogeneity and a stochastic one. It is found that vertical oscillations of a sound-speed perturbation can affect rays in a resonant manner. Such resonances give rise to chaos in certain regions of phase space. It is shown that stability of steep rays, being observed in experiments, is connected with suppression of resonances in the case of small-scale vertical sound-speed oscillations.

physics.ao-ph↗

arXiv2005

Noise-induced clustering in Hamiltonian systems

The motion of oscillatory-like nonlinear Hamiltonian systems, driven by a weak noise, is considered. A general method to find regions of stability in the phase space of a randomly-driven system, based on a specific Poincaré map, is proposed and justified. Physical manifestations of these regions of stability, the so-called coherent clusters, are demonstrated with two models in ocean physics. We find bunches of sound rays propagating coherently in an underwater waveguide through a randomly fluctuating ocean at long distances. We find clusters of passive particles to be advected coherently by a random two-dimensional flow modelling mixing around a topographic eddy in the ocean.

nlin.CD↗

arXiv2003

Ray chaos and ray clustering in an ocean waveguide

We consider ray propagation in a waveguide with a designed sound-speed profile perturbed by a range-dependent perturbation caused by internal waves in deep ocean environments. The Hamiltonian formalism in terms of the action and angle variables is applied to study nonlinear ray dynamics with two sound-channel models and three perturbation models: a single-mode perturbation, a random-like sound-speed fluctuations, and a mixed perturbation. In the integrable limit without any perturbation, we derive analytical expressions for ray arrival times and timefronts at a given range, the main measurable characteristics in field experiments in the ocean. In the presence of a single-mode perturbation, ray chaos is shown to arise as a result of overlapping nonlinear ray-medium resonances. Poincaré maps, plots of variations of the action per a ray cycle length, and plots with rays escaping the channel reveal inhomogeneous structure of the underlying phase space with remarkable zones of stability where stable coherent ray clusters may be formed. We demonstrate the possibility of determining the wavelength of the perturbation mode from the arrival time distribution under conditions of ray chaos. It is surprising that coherent ray clusters, consisting of fans of rays which propagate over long ranges with close dynamical characteristics, can survive under a random-like multiplicative perturbation modelling sound-speed fluctuations caused by a wide spectrum of internal waves.

nlin.CD↗