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Jun 30, 2018
06/18

by
N. S. Voronova; Yu. E. Lozovik

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We discuss the coherent oscillations between two coupled quantum states of a Bose-Einstein condensate in two-dimensional space at zero temperature. In the system we consider, weak interparticle repulsive interactions occur between the particles in state one only, while the state two particles remain non-interacting. Analytical as well as numerical solution of the coupled Gross-Pitaevskii and Schroedinger equations reveals various regimes of oscillational dynamics for the relative quantum phase...

Topics: Quantum Gases, Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1411.2346

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41

Sep 19, 2013
09/13

by
Yu. E. Lozovik; A. M. Ruvinsky

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The transport relaxation time $\tau (P)$ and the mean free path of magnetoexcitons in single and coupled quantum wells are calculated ($P$ is the magnetic momentum of the magnetoexciton). We present the results for magnetoexciton scattering in a random field due to (i) quantum well width fluctuations, (ii) composite fluctuations and (iii) ionized impurities. The time $\tau(P)$ depends nonmonotonously on $P$ in the case (ii) and in the cases (i), (iii) for $D/l$ smaller than some critical value...

Source: http://arxiv.org/abs/cond-mat/9804049v1

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Sep 18, 2013
09/13

by
A. I. Belousov; Yu. E. Lozovik

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Path Integral Quantum Monte Carlo simulation is used to study thermodynamic properties and a phase diagram of 2D quantum Josephson array, described by 2+1 XY model. The helicity and vorticity moduli, correlation function of phases and other characteristics of the system as functions of quantum parameter $q$ and temperature $T$ are studied ($q=2e/\sqrt{JC_0}$, $J$ is the Josephson coupling constant, $C_0$ is the intragrain capacitance). Quantum fluctuation induced superconductor - normal phase...

Source: http://arxiv.org/abs/cond-mat/9803300v1

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Sep 21, 2013
09/13

by
G. E. Astrakharchik; Yu. E. Lozovik

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Possible signatures of a super-Tonks-Girardeau gas in bosonic systems of trapped quasi-one-dimensional dipoles are discussed at zero temperature. We provide estimation of the frequency of the lowest compressional mode and compare it to analytical results derived using harmonic approach in the high density regime. We construct an exact mapping of the ground-state wave function of one-dimensional dipolar system of bosons, fermions and Bose-Fermi mixture and conclude that local properties and...

Source: http://arxiv.org/abs/0709.4609v1

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Sep 19, 2013
09/13

by
Yu. E. Lozovik; A. A. Sokolik

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We consider ground state of electron-hole graphene bilayer composed of two independently doped graphene layers when a condensate of spatially separated electron-hole pairs is formed. In the weak coupling regime the pairing affects only conduction band of electron-doped layer and valence band of hole-doped layer, thus the ground state is similar to ordinary BCS condensate. At strong coupling, an ultrarelativistic character of electron dynamics reveals and the bands which are remote from Fermi...

Source: http://arxiv.org/abs/0910.4366v1

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Sep 23, 2013
09/13

by
A. I. Belousov; Yu. E. Lozovik

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Two dimensional (2D) classical system of dipole particles confined by a quadratic potential is studied. For clusters of N < 81 particles ground state configurations and appropriate eigenfrequencies and eigenvectors for the normal modes are found. Monte Carlo and molecular dynamic methods are used to study in detail the order - disorder transition (the "melting" of clusters). In mesoscopic clusters (N < 37) there is a hierarchy of transitions: at lower temperatures an intershell...

Source: http://arxiv.org/abs/cond-mat/9806108v1

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Sep 17, 2013
09/13

by
Yu. E. Lozovik; I. V. Ovchinnikov

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The novel method of observation and controlling of Bose-Einstein condensation in the system of spatially and momentum-space indirect excitons in coupled quantum wells using in-plane magnetic and normal electric fields is proposed. Fields are used for exciton dispersion engeneering. In the presence of in-plane magnetic field ground state of spatially indirect exciton becomes also indirect in the momentum space. Manipulation of electric field magnitude is used for tuning to resonance of...

Source: http://arxiv.org/abs/cond-mat/0007162v1

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Sep 18, 2013
09/13

by
Yu. E. Lozovik; A. V. Poushnov

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The unusual two-photon emission by Bose-condensed excitons caused by simultaneous recombination of two excitons with opposite momenta leaving the occupation numbers of excitonic states with momenta $p nonequal to 0$ unchanged (below coherent two-exciton recombination) is investigated. Raman scattering accompanied by the analogous two-exciton recombination (or creation) is also analyzed. The excess momentum equal to the change of the electromagnetic field momentum in these processes can be...

Source: http://arxiv.org/abs/cond-mat/9803318v1

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Sep 21, 2013
09/13

by
Yu. E. Lozovik; A. V. Poushnov

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Stimulated two-photon emission by Bose-condensed excitons accompanied by a coherent two-exciton recombination, i.e., by simultaneous recombination of two excitons with opposite momenta leaving unchanged the occupation numbers of excitonic states with nonzero momenta, is investigated. Raman light scattering accompanied by a similar two-exciton recombination (or generation of two excitons) is also analyzed. The processes under consideration can occur only if a system contains Bose condensate,...

Source: http://arxiv.org/abs/cond-mat/9905347v1

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31

Sep 21, 2013
09/13

by
A. I. Belousov; Yu. E. Lozovik

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By path integral Monte Carlo simulations we study the phase diagram of two - dimensional mesoscopic clusters formed by electrons in a semiconductor quantum dot or by indirect magnetoexcitons in double quantum dots. At zero (or sufficiently small) temperature, as quantum fluctuations of particles increase, two types of quantum disordering phenomena take place: first, at small values of quantum de Boer parameter q < 0.01 one can observe a transition from a completely ordered state to that in...

Source: http://arxiv.org/abs/cond-mat/9905194v1

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Jun 29, 2018
06/18

by
A. D. Zabolotskiy; Yu. E. Lozovik

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A tight-binding model of 8-Pmmn borophene, a two-dimensional boron crystal, is developed. We confirm that the crystal hosts massless Dirac fermions and the Dirac points are protected by symmetry. Strain is introduced into the model, and it is shown to induce a pseudomagnetic field vector potential and a scalar potential. The dependence of the potentials on the strain tensor is calculated. The physical effects controlled by pseudomagnetic field are discussed.

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1607.02530

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Sep 23, 2013
09/13

by
Yu. E. Lozovik; A. A. Sokolik

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Massless Dirac electrons in graphene fill Landau levels with energies scaled as square roots of their numbers. Coulomb interaction between electrons leads to mixing of different Landau levels. The relative strength of this interaction depends only on dielectric susceptibility of surrounding medium and can be large in suspended graphene. We consider influence of Landau level mixing on the properties of magnetoexcitons and magnetoplasmons - elementary electron-hole excitations in graphene in...

Source: http://arxiv.org/abs/1111.1176v2

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Sep 19, 2013
09/13

by
Yu. E. Lozovik; A. M. Popov

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Theory of adsorption on a surface with nanolocal defects is proposed. Two efficacy parameters of surface modification for nanotechnological purposes are introduced, where the modification is a creation of nanolocal artificial defects. The first parameter corresponds to applications where it is necessary to increase the concentration of certain particles on the modified surface. And the second one corresponds to the pattern transfer with the help of particle self-organization on the modified...

Source: http://arxiv.org/abs/physics/9804012v1

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Jul 19, 2013
07/13

by
Yu. E. Lozovik; A. A. Sokolik

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The possibility of superconducting pairing of electrons in doped graphene due to in-plane and out-of-plane phonons is studied. Quadratic coupling of electrons with out-of-plane phonons is considered in details, taking into account both deformation potential and bond-stretch contributions. The order parameter of electron-electron pairing can have different structures due to four-component spinor character of electrons wave function. We consider s-wave pairing, diagonal on conduction and valence...

Source: http://arxiv.org/abs/1005.4852v1

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46

Sep 22, 2013
09/13

by
Yu. E. Lozovik; A. A. Sokolik

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We consider the pairing of electrons and holes due to their Coulomb attraction in two parallel, independently gated graphene layers, separated by a barrier. At weak coupling, there exist the BCS-like pair-condensed state. Despite the fact that electrons and holes behave like massless Dirac fermions, the problem of BCS-like electron-hole pairing in graphene bilayer turns out to be rather similar to that in usual coupled semiconductor quantum wells. The distinctions are due to Berry phase of...

Source: http://arxiv.org/abs/0812.4840v1

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29

Sep 18, 2013
09/13

by
A. I. Belousov; Yu. E. Lozovik

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Quantum fluctuations of the phases of the order parameter in 2D arrays of mesoscopic Josephson junctions and their effect on the destruction of superconductivity in the system are investigated by means of a quantum-cosine model that is free of the incorrect application of the phase operator. The proposed model employs trigonometric phase operators and makes it possible to study arrays of small superconducting granules, pores filled with superfluid helium, or Josephson junctions in which the...

Source: http://arxiv.org/abs/cond-mat/9803382v1

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Sep 23, 2013
09/13

by
D. K. Efimkin; Yu. E. Lozovik; A. A. Sokolik

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We study collective excitations in a helical electron liquid on a surface of three-dimensional topological insulator. Electron in helical liquid obeys Dirac-like equation for massless particless and direction of its spin is strictly determined by its momentum. Due to this spin-momentum locking, collective excitations in the system manifest themselves as coupled charge- and spin-density waves. We develop quantum field-theoretical description of spin-plasmons in helical liquid and study their...

Source: http://arxiv.org/abs/1110.4023v1

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Sep 21, 2013
09/13

by
Yu. E. Lozovik; O. L. Berman; V. G. Tsvetus

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Superfluidity of spatially separated electrons and holes and unbalanced two-layer electron system in high magnetic field is considered. The temperature of the Kosterlitz-Thouless transition to a superfluid state is obtained as a function of magnetic field and interlayer separation. The equation of state for magnetoexciton system in quasi-classical regime is analyzed. The transition from excitonic phase to electron-hole phase is considered. Possible experimental manifestations of the predicted...

Source: http://arxiv.org/abs/cond-mat/9905004v1

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Sep 23, 2013
09/13

by
A. Filinov; P. Ludwig; M. Bonitz; Yu. E. Lozovik

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Using an adiabatic approximation we derive an effective interaction potentially for spatially indirect excitons. Using this potential and path integral Monte Carlo simulations we study exciton crystllization and the quantum melting phase transition in a macroscopic system of 2D excitons. Furthermore, the superfluid fraction is calculated as a function of density and shown to vanish upon crystallization. We show that the commonly used dipole model fails to correctly describe indirect excitons in...

Source: http://arxiv.org/abs/0810.2730v1

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Jul 19, 2013
07/13

by
Yu. E. Lozovik; S. L. Ogarkov; A. A. Sokolik

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The superconducting pairing of electrons in doped graphene due to in-plane and out-of-plane phonons is considered. It is shown that the structure of the order parameter in the valley space substantially affects conditions of the pairing. Electron-hole pairing in graphene bilayer in the strong coupling regime is also considered. Taking into account retardation of the screened Coulomb pairing potential shows a significant competition between the electron-hole direct attraction and their repulsion...

Source: http://arxiv.org/abs/1005.4857v1

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Sep 21, 2013
09/13

by
G. E. Astrakharchik; A. I. Belousov; Yu. E. Lozovik

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Two-dimensional classical cluster of particles interacting through a screened Coulomb potential is studied. This system can be used as a model for "dusty particles" in high-frequency discharge plasma. For systems consisting of N = 2 - 40 particles and confined by a harmonic potential we find ground-state configurations, eigenfrequencies and eigenvectors for the normal modes as a function of the Debye screening length R_D in plasma. Variations in R_D cause changes in the ground-state...

Source: http://arxiv.org/abs/cond-mat/9905193v1

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1.0

Jun 28, 2018
06/18

by
A. A. Sokolik; A. D. Zabolotskiy; Yu. E. Lozovik

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The virial theorem for a system of interacting electrons in a crystal, which is described within the framework of the tight-binding model, is derived. We show that, in particular case of interacting massless electrons in graphene and other Dirac materials, the conventional virial theorem is violated. Starting from the tight-binding model, we derive the generalized virial theorem for Dirac electron systems, which contains an additional term associated with a momentum cutoff at the bottom of the...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1512.05683

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Sep 23, 2013
09/13

by
A. E. Golomedov; G. E. Astrakharchik; Yu. E. Lozovik

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A mesoscopic system of indirect dipolar bosons trapped by a harmonic potential is considered. The system has a number of physical realizations including dipole excitons, atoms with large dipolar moment, polar molecules, Rydberg atoms in inhomogenious electric field. We carry out a diffusion Monte Carlo simulation to define the quantum properties of a two-dimensional system of trapped dipoles at zero temperature. In dimensionless units the system is described by two control parameters, namely...

Source: http://arxiv.org/abs/1105.4075v1

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38

Sep 23, 2013
09/13

by
Yu. E. Lozovik; S. L. Ogarkov; A. A. Sokolik

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Cooper pairing of spatially separated electrons and holes in graphene bilayer is studied beyond the mean-field approximation. Suppression of the screening at large distances, caused by appearance of the gap, is considered self-consistently. A mutual positive feedback between appearance of the gap and enlargement of the interaction leads to a sharp transition to correlated state with greatly increased gap above some critical value of the coupling strength. At coupling strength below the...

Source: http://arxiv.org/abs/1202.4978v2

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39

Sep 17, 2013
09/13

by
A. Filinov; J. Böning; M. Bonitz; Yu. E. Lozovik

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When a few tens of charged particles are trapped in a spherical electrostatic potential at low temperature they form concentric shells resembling atoms. These ``artificial atoms'' can be easily controlled by varying the confinement strength. We analyze such systems for the case that the particles are bosons and find superfluid behavior which even persists in the solid state. This novel state of matter is a mesoscopic supersolid.

Source: http://arxiv.org/abs/0711.1255v1

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Sep 21, 2013
09/13

by
A. N. Poddubny; E. L. Ivchenko; Yu. E. Lozovik

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Transmission, reflection and absorption of electromagnetic radiation and photon dispersion law for 2D photonic crystals with superconducting elements are studied. The calculation of optical properties of photonic crystals is studied by layer-by-layer Korringa-Kohn-Rostoker techniques. The results of numerical calculations performed for an array of superconducting cylinders have been understood in terms of a simple analytical model. The controlling of optical properties of superconducting...

Source: http://arxiv.org/abs/0709.0779v1

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Sep 23, 2013
09/13

by
Yu. E. Lozovik; I. L. Kurbakov; M. Willander

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Superfluid exciton density and superfluid transition (crossover) temperature are calculated for 2D excitons in large-size flat and harmonic traps. A generalized local density approximation for the Kosterlitz-Thouless theory is developed.

Source: http://arxiv.org/abs/0801.0152v1

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Jun 30, 2018
06/18

by
Yu. E. Lozovik; A. A. Sokolik; A. D. Zabolotskiy

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Many-body effects on quantum capacitance, compressibility, renormalized Fermi velocity, kinetic and interaction energies of massless Dirac electrons in graphene, induced by the Coulomb interactions, are analyzed theoretically in the first-order, Hartree-Fock and random phase approximations. Recent experimental data on quantum capacitance and renormalized Fermi velocity are analyzed and compared with the theory. The bare Fermi velocity and the effective dielectric constants are obtained from the...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1410.8809

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0.0

Jun 29, 2018
06/18

by
A. A. Sokolik; A. D. Zabolotskiy; Yu. E. Lozovik

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In strong magnetic fields, massless electrons in graphene populate relativistic Landau levels with the square-root dependence of each level energy on its number and magnetic field. Interaction-induced deviations from this single-particle picture were observed in recent experiments on cyclotron resonance and magneto-Raman scattering. Previous attempts to calculate such deviations theoretically using the unscreened Coulomb interaction resulted in overestimated many-body effects. This work...

Topics: Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1612.06663

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Sep 22, 2013
09/13

by
Yu. E. Lozovik; V. A. Sharapov; A. S. Arkhipov

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The new method for the simulation of nonstationary quantum processes is proposed. The method is based on the tomography representation of quantum mechanics, {\it i.e.}, the state of the system is described by the {\it nonnegative} function (quantum tomogram). In the framework of the method one uses the ensemble of trajectories in the tomographic space to represent evolution of the system (therefore direct calculation of the quantum tomogram is avoided). To illustrate the method we consider the...

Source: http://arxiv.org/abs/cond-mat/0309529v1

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255

Jul 20, 2013
07/13

by
D. K. Efimkin; Yu. E. Lozovik; A. A. Sokolik

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Collective plasmon excitations in a helical electron liquid on the surface of strong three-dimensional topological insulator are considered. The properties and internal structure of these excitations are studied. Due to spin-momentum locking in helical liquid on a surface of topological insulator, the collective excitations should manifest themselves as coupled charge- and spin-density waves.

Source: http://arxiv.org/abs/1107.4695v1

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Sep 22, 2013
09/13

by
A. S. Arkhipov; Yu. E. Lozovik; V. I. Man'ko

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The tomographic map of quantum state of a system with several degrees of freedom which depends on one random variable, analogous to center of mass considered in rotated and scaled reference frame in the phase space, is constructed. Time evolution equation of the tomogram for this map is given in explicit form. Properties of the map like the transition probabilities between the different states and relation to the star product formalism are elucidated. Example of multimode oscillator is...

Source: http://arxiv.org/abs/quant-ph/0310028v1

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37

Sep 22, 2013
09/13

by
Yu. E. Lozovik; A. V. Filinov; A. S. Arkhipov

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We demonstrate a new method of simulation of nonstationary quantum processes, considering the tunneling of two {\it interacting identical particles}, represented by wave packets. The used method of quantum molecular dynamics (WMD) is based on the Wigner representation of quantum mechanics. In the context of this method ensembles of classical trajectories are used to solve quantum Wigner-Liouville equation. These classical trajectories obey Hamilton-like equations, where the effective potential...

Source: http://arxiv.org/abs/cond-mat/0309528v1

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Jun 30, 2018
06/18

by
A. K. Fedorov; I. L. Kurbakov; Yu. E. Lozovik

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The formation of the roton-maxon excitation spectrum and the roton instability effect for a weakly correlated Bose gas of dipolar excitons in a semiconductor layer are predicted. The stability diagram is calculated. According to our numerical estimations, the threshold of the roton instability for Bose-Einstein condensed exciton gas with roton-maxon spectrum is achievable experimentally, e.g., in GaAs semiconductor layers.

Topics: Quantum Gases, Condensed Matter

Source: http://arxiv.org/abs/1403.3956

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Sep 18, 2013
09/13

by
A. V. Filinov; M. Bonitz; Yu. E. Lozovik

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Wigner crystallization of electrons in a 2D quantum dots is reported. It proceeds in two stages: I) via radial ordering of electrons on shells and II) freezing of the inter-shell rotation. The phase boundary of the crystal is computed in the whole temperature--density plane, and the influence of quantum effects and of the particle number is analyzed.

Source: http://arxiv.org/abs/cond-mat/0012265v1

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Sep 18, 2013
09/13

by
A. M. Fedotov; N. B. Narozhny; Yu. E. Lozovik

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We consider an atom interacting with a quantized electromagnetic field inside a cavity with variable parameters. The atom in the ground state located in the initially empty cavity can be excited by variation of cavity parameters. We have discovered two mechanisms of atomic excitation. The first arises due to the interaction of the atom with the non-stationary electromagnetic field created by modulation of cavity parameters. If the characteristic time of variation of cavity parameters is of the...

Source: http://arxiv.org/abs/quant-ph/0008066v2

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Sep 20, 2013
09/13

by
D. K. Efimkin; Yu. E. Lozovik; A. A. Sokolik

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We consider pairing of massless Dirac electrons and holes located on opposite surfaces of thin film of "strong" three-dimensional topological insulator. Such pairing was predicted to give rise to topological exciton condensate with unusual properties. We estimate quantitatively achievable critical temperature of the pairing with taking into account self-consistent screening of the Coulomb interaction, disorder and hybridization of electron and hole states caused by a tunneling through...

Source: http://arxiv.org/abs/1207.1817v3

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Sep 19, 2013
09/13

by
A. V. Filinov; M. Bonitz; Yu. E. Lozovik

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We present results of Monte-Carlo simulations for finite 2D single and bilayer systems. Strong Coulomb correlations lead to arrangement of particles in configurations resembling a crystal lattice. For binary layers, there exists a particularly rich variety of lattice symmetries which depend on the interlayer separation $d$. We demonstrate that in these mesoscopic lattices there exist two fundamental types of ordering: radial and orientational. The dependence of the melting temperature on $d$ is...

Source: http://arxiv.org/abs/cond-mat/0102279v1

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28

Sep 18, 2013
09/13

by
Yu. E. Lozovik; S. A. Verzakov; M. Willander

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The superfluidity and Bose-Einstein condensation of indirect excitons in two-dimensional quantum dot are studied by path-integral Monte Carlo simulations. The temperature dependence of superfluid and bose-condensed fraction are calculated at different strengths of interaction. Using the Kosterlitz-Thouless recursion relations, we also predict behavior of superfluid fraction in macroscopic large systems.

Source: http://arxiv.org/abs/cond-mat/9811037v1

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Sep 17, 2013
09/13

by
J. Böning; A. Filinov; P. Ludwig; H. Baumgartner; M. Bonitz; Yu. E. Lozovik

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In small confined systems predictions for the melting point strongly depend on the choice of quantity and on the way it is computed, even yielding divergent and ambiguous results. We present a very simple quantity which allows to control these problems -- the variance of the block averaged interparticle distance fluctuations.

Source: http://arxiv.org/abs/0711.1124v1

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Sep 20, 2013
09/13

by
G. E. Astrakharchik; J. Boronat; I. L. Kurbakov; Yu. E. Lozovik

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The ground-state phase diagram of a two-dimensional Bose system with dipole-dipole interactions is studied by means of quantum Monte Carlo technique. Our calculation predicts a quantum phase transition from gas to solid phase when the density increases. In the gas phase the condensate fraction is calculated as a function of the density. Using Feynman approximation, the collective excitation branch is studied and appearance of a roton minimum is observed. Results of the static structure factor...

Source: http://arxiv.org/abs/cond-mat/0608246v3

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Sep 22, 2013
09/13

by
Yu. E. Lozovik; I. L. Kurbakov; G. E. Astrakharchik; M. Willander

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The Bose condensation of 2D dipolar excitons in quantum wells is numerically studied by the diffusion Monte Carlo simulation method. The correlation, microscopic, thermodynamic, and spectral characteristics are calculated. It is shown that, in structures of coupled quantum wells, in which low-temperature features of exciton luminescence have presently been observed, dipolar excitons form a strongly correlated system. Their Bose condensation can experimentally be achieved much easily than for...

Source: http://arxiv.org/abs/0812.4837v1

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Sep 21, 2013
09/13

by
O. N. Osychenko; G. E. Astrakharchik; Y. Lutsyshyn; Yu. E. Lozovik; J. Boronat

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We report a quantum Monte Carlo calculation of the phase diagram of bosons interacting with a repulsive inverse sixth power pair potential, a model for assemblies of Rydberg atoms in the local van der Waals blockade regime. The model can be parametrized in terms of just two parameters, the reduced density and temperature. Solidification happens to the fcc phase. At zero temperature the transition density is found with the diffusion Monte Carlo method at density $\rho = 3.9 (\hbar^2/m C_6)^{3/4}...

Source: http://arxiv.org/abs/1106.2997v2

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Sep 18, 2013
09/13

by
P. Ludwig; A. Filinov; Yu. E. Lozovik; H. Stolz; M. Bonitz

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We consider a \textit{mass-asymmetric} electron and hole bilayer. Electron and hole Coulomb correlations and electron and hole quantum effects are treated on first princles by path integral Monte Carlo methods. For a fixed layer separation we vary the mass ratio $M$ of holes and electrons between 1 and 100 and analyze the structural changes in the system. While, for the chosen density, the electrons are in a nearly homogeneous state, the hole arrangement changes from homogeneous to localized,...

Source: http://arxiv.org/abs/cond-mat/0611556v1

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Jul 20, 2013
07/13

by
A. M. Fedotov; Yu. E. Lozovik; N. B. Narozhny; A. N. Petrosyan

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We consider particle creation (the Dynamical Casimir effect) in a uniformly contracting ideal one-dimensional cavity non-perturbatively. The exact expression for the energy spectrum of created particles is obtained and its dependence on parameters of the problem is discussed. Unexpectedly, the number of created particles depends on the duration of the cavity contracting non-monotonously. This is explained by quantum interference of the events of particle creation which are taking place only at...

Source: http://arxiv.org/abs/quant-ph/0604058v1

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Sep 19, 2013
09/13

by
L. V. Butov; A. V. Mintsev; Yu. E. Lozovik; K. L. Campman; A. C. Gossard

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In-plane magnetic field is found to change drastically the photoluminescence spectra and kinetics of interwell excitons in GaAs/AlGaAs coupled quantum wells. The effect is due to the in-plane magnetic field induced displacement of the interwell exciton dispersion in a momentum space, which results in the transition from the momentum-space direct exciton ground state to the momentum-space indirect exciton ground state. In-plane magnetic field is, therefore, an effective tool for the exciton...

Source: http://arxiv.org/abs/cond-mat/9912242v1

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0.0

Jun 29, 2018
06/18

by
A. A. Zhukov; D. S. Shapiro; S. V. Remizov; W. V. Pogosov; Yu. E. Lozovik

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We consider a superconducting qubit coupled to the nonstationary transmission line cavity with modulated frequency taking into account energy dissipation. Previously, it was demonstrated that in the case of a single nonadiabatical modulation of a cavity frequency there are two channels of a two-level system excitation which are due to the absorption of Casimir photons and due to the counterrotating wave processes responsible for the dynamical Lamb effect. We show that the parametric periodical...

Topics: Mesoscale and Nanoscale Physics, Quantum Physics, Condensed Matter, Superconductivity

Source: http://arxiv.org/abs/1607.03054

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28

Sep 18, 2013
09/13

by
A. S. Arkhipov; G. E. Astrakharchik; A. V. Belikov; Yu. E. Lozovik

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A one-dimensional (1D) Bose system with dipole-dipole repulsion is studied at zero temperature by means of a Quantum Monte Carlo method. It is shown that in the limit of small linear density the bosonic system of dipole moments acquires many properties of a system of non-interacting fermions. At larger linear densities a Variational Monte Carlo calculation suggests a crossover from a liquid-like to a solid-like state. The system is superfluid on the liquid-like side of the crossover and is...

Source: http://arxiv.org/abs/cond-mat/0505700v1

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1.0

Jun 30, 2018
06/18

by
A. K. Fedorov; I. L. Kurbakov; Y. E. Shchadilova; Yu. E. Lozovik

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We predict the effect of the roton instability for a two-dimensional weakly interacting gas of tilted dipoles in a single homogeneous quantum layer. Being typical for strongly correlated systems, the roton phenomena appear to occur in a weakly interacting gas. It is important that in contrast to a system of normal to wide layer dipoles, breaking of the rotational symmetry for a system of tilted dipoles leads to the convergence of the condensate depletion even up to the threshold of the roton...

Topics: Quantum Gases, Mesoscale and Nanoscale Physics, Condensed Matter

Source: http://arxiv.org/abs/1407.6399

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3.0

Jun 27, 2018
06/18

by
D. S. Shapiro; A. A. Zhukov; W. V. Pogosov; Yu. E. Lozovik

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A natural atom placed into a cavity with time-dependent parameters can be parametrically excited due to the interaction with the quantized photon mode. One of the channels of such a process is the dynamical Lamb effect, induced by a nonadiabatic modulation of atomic level Lamb shift. However, in experiments with natural atoms it is quite difficult to isolate this effect from other mechanisms of atom excitation. We point out that a transmission line cavity coupled with a superconducting qubit...

Topics: Condensed Matter, Quantum Physics, Atomic Physics, Superconductivity, Mesoscale and Nanoscale...

Source: http://arxiv.org/abs/1503.01666