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Автор: Grafiati

Опубліковано: 14 березня 2023

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1

HUTCHINSON, D. A. W., and P. B. BLAKIE. "PHASE TRANSITIONS IN ULTRA-COLD TWO-DIMENSIONAL BOSE GASES." International Journal of Modern Physics B 20, no. 30n31 (December 20, 2006): 5224–28. http://dx.doi.org/10.1142/s0217979206036302.

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Анотація:

We briefly review the theory of Bose-Einstein condensation in the two-dimensional trapped Bose gas and, in particular the relationship to the theory of the homogeneous two-dimensional gas and the Berezinskii-Kosterlitz-Thouless phase. We obtain a phase diagram for the trapped two-dimensional gas, finding a critical temperature above which the free energy of a state with a pair of vortices of opposite circulation is lower than that for a vortex-free Bose-Einstein condensed ground state. We identify three distinct phases which are, in order of increasing temperature, a phase coherent Bose-Einstein condensate, a vortex pair plasma with fluctuating condensate phase and a thermal Bose gas. The thermal activation of vortex-antivortex pair formation is confirmed using finite-temperature classical field simulations.

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2

Navez, Patric. "Macroscopic Squeezing in Bose–Einstein Condensate." Modern Physics Letters B 12, no. 18 (August 10, 1998): 705–13. http://dx.doi.org/10.1142/s0217984998000822.

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We study the ground state of a uniform Bose gas at zero temperature in the Hartree–Fock–Bogoliubov (HFB) approximation. We find a solution of the HFB equations which obeys the Hugenholtz–Pines theorem. This solution imposes a macroscopic squeezing to the condensed state and as a consequence displays large particle number fluctuations. Particle number conservation is restored by building the appropriate U(1) invariant ground state via the superposition of the squeezed states. The condensed particle number distribution of this new ground state is calculated as well as its fluctuations which present a normal behavior.

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3

Kudo, K., M. Yamazaki, T. Kawamata, T. Noji, Y. Koike, T. Nishizaki, N. Kobayashi, and H. Tanaka. "Thermal conductivity in the Bose–Einstein condensed state of TlCuCl3." Journal of Magnetism and Magnetic Materials 272-276 (May 2004): 214–15. http://dx.doi.org/10.1016/j.jmmm.2003.12.419.

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4

Pereira, Lucas Carvalho, and Valter Aragão do Nascimento. "Dynamics of Bose–Einstein Condensates Subject to the Pöschl–Teller Potential through Numerical and Variational Solutions of the Gross–Pitaevskii Equation." Materials 13, no. 10 (May 13, 2020): 2236. http://dx.doi.org/10.3390/ma13102236.

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Анотація:

We present for the first time an approach about Bose–Einstein condensates made up of atoms with attractive interatomic interactions confined to the Pöschl–Teller hyperbolic potential. In this paper, we consider a Bose–Einstein condensate confined in a cigar-shaped, and it was modeled by the mean field equation known as the Gross–Pitaevskii equation. An analytical (variational method) and numerical (two-step Crank–Nicolson) approach is proposed to study the proposed model of interatomic interaction. The solutions of the one-dimensional Gross–Pitaevskii equation obtained in this paper confirmed, from a theoretical point of view, the possibility of the Pöschl–Teller potential to confine Bose–Einstein condensates. The chemical potential as a function of the depth of the Pöschl–Teller potential showed a behavior very similar to the cases of Bose–Einstein condensates and superfluid Fermi gases in optical lattices and optical superlattices. The results presented in this paper can open the way for several applications in atomic and molecular physics, solid state physics, condensed matter physics, and material sciences.

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5

Keeling, Jonathan, and Stéphane Kéna-Cohen. "Bose–Einstein Condensation of Exciton-Polaritons in Organic Microcavities." Annual Review of Physical Chemistry 71, no. 1 (April 20, 2020): 435–59. http://dx.doi.org/10.1146/annurev-physchem-010920-102509.

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Анотація:

Bose–Einstein condensation describes the macroscopic occupation of a single-particle mode: the condensate. This state can in principle be realized for any particles obeying Bose–Einstein statistics; this includes hybrid light-matter excitations known as polaritons. Some of the unique optoelectronic properties of organic molecules make them especially well suited for the realization of polariton condensates. Exciton-polaritons form in optical cavities when electronic excitations couple collectively to the optical mode supported by the cavity. These polaritons obey bosonic statistics at moderate densities, are stable at room temperature, and have been observed to form a condensed or lasing state. Understanding the optimal conditions for polariton condensation requires careful modeling of the complex photophysics of organic molecules. In this article, we introduce the basic physics of exciton-polaritons and condensation and review experiments demonstrating polariton condensation in molecular materials.

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6

ROUBTSOV, D., and Y. LÉPINE. "EXCITON-PHONON PACKETS WITH BOSE–EINSTEIN CONDENSATE." International Journal of Modern Physics B 17, no. 28 (November 10, 2003): 5289–93. http://dx.doi.org/10.1142/s0217979203020429.

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Анотація:

We discuss the possibility for a moving droplet of excitons and phonons to form a coherent state inside the packet. We describe such an inhomogeneous state in terms of Bose–Einstein condensation and prescribe it a macroscopic wave function. Existence and, thus, coherency of such a Bose-core inside the droplet can be checked experimentally if two moving packets are allowed to interact.

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7

LI, ZHIBING, and CHENGGUANG BAO. "SPINOR BEC IN THE LARGE-N LIMIT." International Journal of Modern Physics B 21, no. 23n24 (September 30, 2007): 4248–55. http://dx.doi.org/10.1142/s0217979207045487.

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The superfine structure of Bose-Einstein condensate of alkali atoms due to the spin coupling have been investigated in the mean field approximation. In the limit of large number of atoms, we obtained the analytical solution for the fully condensed states and the states with one-atom excited. It was found that the energy of the one-atom excited state could be smaller than the energy of the fully condensed state, even two states have similar total spin.

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8

Yukalov, V. I., and E. P. Yukalova. "Dynamics of Nonground-State Bose-Einstein Condensates." Journal of Low Temperature Physics 138, no. 3-4 (February 2005): 657–62. http://dx.doi.org/10.1007/s10909-005-2279-y.

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9

KASAMATSU, KENICHI, MAKOTO TSUBOTA, and MASAHITO UEDA. "VORTICES IN MULTICOMPONENT BOSE–EINSTEIN CONDENSATES." International Journal of Modern Physics B 19, no. 11 (April 30, 2005): 1835–904. http://dx.doi.org/10.1142/s0217979205029602.

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Анотація:

We review the topic of quantized vortices in multicomponent Bose–Einstein condensates of dilute atomic gases, with an emphasis on the two-component condensates. First, we review the fundamental structure, stability and dynamics of a single vortex state in a slowly rotating two-component condensates. To understand recent experimental results, we use the coupled Gross–Pitaevskii equations and the generalized nonlinear sigma model. An axisymmetric vortex state, which was observed by the JILA group, can be regarded as a topologically trivial skyrmion in the pseudospin representation. The internal, coherent coupling between the two components breaks the axisymmetry of the vortex state, resulting in a stable vortex molecule (a meron pair). We also mention unconventional vortex states and monopole excitations in a spin-1 Bose–Einstein condensate. Next, we discuss a rich variety of vortex states realized in rapidly rotating two-component Bose–Einstein condensates. We introduce a phase diagram with axes of rotation frequency and the intercomponent coupling strength. This phase diagram reveals unconventional vortex states such as a square lattice, a double-core lattice, vortex stripes and vortex sheets, all of which are in an experimentally accessible parameter regime. The coherent coupling leads to an effective attractive interaction between two components, providing not only a promising candidate to tune the intercomponent interaction to study the rich vortex phases but also a new regime to explore vortex states consisting of vortex molecules characterized by anisotropic vorticity. A recent experiment by the JILA group vindicated the formation of a square vortex lattice in this system.

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10

CRISAN, M., and I. GROSU. "BOSE–EINSTEIN QUASICONDENSATION IN 2D SYSTEMS." Modern Physics Letters B 19, no. 17 (July 30, 2005): 821–27. http://dx.doi.org/10.1142/s0217984905008852.

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Анотація:

We calculate the finite temperature correlation function, the coherence length and the critical temperature for a two-dimensional (2D) bosonic system, which presents the quasicondensation (a finite number of occupied states with p0≠0 momentum) effect at very low temperatures. This state, discovered experimentally, appear below a critical temperature for a finite number of particles.

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11

Luo, Dekun, and Lan Yin. "Critical temperature of pair condensation in a dilute Bose gas with spin–orbit coupling." International Journal of Modern Physics B 31, no. 25 (October 10, 2017): 1745012. http://dx.doi.org/10.1142/s0217979217450126.

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Анотація:

We study the Bardeen–Cooper–Shrieffer (BCS) pairing state of a two-component Bose gas with a symmetric spin–orbit coupling (SOC). In the dilute limit at low temperature, this system is essentially a dilute gas of diatomic molecules. We compute the effective mass of the molecule and find that it is anisotropic in momentum space. The critical temperature of the pairing state is about eight times smaller than the Bose–Einstein condensation (BEC) transition temperature of an ideal Bose gas with the same density.

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12

Zuo, Da-Wei, and Xiao-Shuo Xiang. "Soliton interaction in the Bose–Einstein condensate." Modern Physics Letters B 34, no. 32 (September 10, 2020): 2050362. http://dx.doi.org/10.1142/s0217984920503625.

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Анотація:

Wave function of the Bose–Einstein condensate satisfies the nonlinear evolution equation set, which is composed of the driven-dissipative Gross–Pitaevskii equations and rate equation (GPR). In this paper, a three coupled GPR equation is studied. By virtue of the bilinear method, multi-soliton solutions of this GPR equation are attained. Propagation and interaction of the solitons are discussed: propagation direction of the solitons are determined by the wave number; repellent and attractive two solitons are obtained by virtue of adjustment the wave numbers; interaction of the two solitons bound state are discussed; three solitons bound state are attained.

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13

Kudo, Kazutaka, Mitsuhiro Yamazaki, Takayuki Kawamata, Takashi Noji, Yoji Koike, Terukazu Nishizaki, Norio Kobayashi, and Hidekazu Tanaka. "Drastic Enhancement of Thermal Conductivity in the Bose–Einstein Condensed State of TlCuCl3." Journal of the Physical Society of Japan 73, no. 9 (September 15, 2004): 2358–61. http://dx.doi.org/10.1143/jpsj.73.2358.

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14

Oguri, Akira, and Kazumasa Miyake. "Nuclear Spin Relaxation of Spin-Polarized Atomic Hydrogen in Bose-Einstein Condensed State." Journal of the Physical Society of Japan 55, no. 2 (February 15, 1986): 457–60. http://dx.doi.org/10.1143/jpsj.55.457.

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15

Mardonov, Shukhrat N., Bobir A. Toshmatov, Bobomurat J. Ahmedov, and Shukurillo T. Inoyatov. "Polaron Dynamics in a Quasi-Two-Dimensional Bose–Einstein Condensate." Universe 9, no. 2 (February 8, 2023): 89. http://dx.doi.org/10.3390/universe9020089.

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Анотація:

The concept of polaron quasiparticles was first introduced in the pioneering papers by Landau and Feynman in the 1930s and 1940s. It describes the phenomenon of an external particle producing a bound state in an embedded medium. Since then, the study of polaron quasiparticles has been an active area of research in condensed matter physics, with a wide range of applications in magnetic phenomena and lattice deformation properties. In this paper, we provide a comprehensive review of the polaron quasiparticle phenomenon, including its historical origins, theoretical developments, and current research. We also study the various applications of polaron quasiparticles in condensed matter physics, including in magnetic phenomena and lattice deformation properties. The review concludes with an outlook on future directions of research in this field. In particular, we study the motion of external embedded particles in a quasi-two-dimensional Bose–Einstein condensate confined by the quantum harmonic oscillator. We found that the dynamics of attracting particles with static Bose–Einstein condensate exhibit circular and precessional elliptic trajectories due to centripetal force. Polaron-forming embedded particles in the condensate lead to a strongly nonlinear trajectory of the polaron and dynamics of condensate depending on the initial parameters of the condensate and polaron.

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16

ALBERGAMO, FRANCESCO. "EXCITATIONS IN CONFINED LIQUID 4He." Modern Physics Letters B 19, no. 04 (February 28, 2005): 135–56. http://dx.doi.org/10.1142/s0217984905008189.

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Анотація:

The spectacular properties of liquid helium at low temperature are generally accepted as the signature of the bosonic nature of this system. Particularly the superfluid phase is identified with a Bose–Einstein condensed fluid. However, the relationship between the superfluidity and the Bose–Einstein condensation is still largely unknown. Studying a perturbed liquid 4 He system would provide information on the relationship between the two phenomena. Liquid 4 He confined in porous media provides an excellent example of a boson system submitted to disorder and finite-size effects. Much care should be paid to the sample preparation, particularly the confining condition should be defined quantitatively. To achieve homogeneous confinement conditions, firstly a suitable porous sample should be selected, the experiments should then be conducted at a lower pressure than the saturated vapor pressure of bulk helium. Several interesting effects have been shown in confined 4 He samples prepared as described above. Particularly we report the observation of the separation of the superfluid-normal fluid transition temperature, T c , from the temperature at which the Bose–Einstein condensation is believed to start, T BEC , the existence of metastable densities for the confined liquid accessible to the bulk system as a short-lived metastable state only and strong clues for a finite lifetime of the elementary excitations at temperatures as low as 0.4 K .

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17

Salasnich, Luca. "The Role of Dimensionality in the Stability of a Confined Condensed Bose Gas." Modern Physics Letters B 11, no. 29 (December 20, 1997): 1249–54. http://dx.doi.org/10.1142/s0217984997001493.

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Анотація:

We study analytically the ground-state stability of a Bose–Einstein condensate (BEC) confined in an harmonic trap with repulsive or attractive zero-range interaction by minimizing the energy functional of the system. In the case of repulsive interaction the BEC mean radius grows by increasing the number of bosons, instead in the case of attractive interaction the BEC mean radius decreases by increasing the number of bosons: to zero if the system is one-dimensional and to a constant minimum radius, with a maximum number of bosons, if the system is three-dimensional.

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18

Wu, Rukuan, and Yu Shi. "Ground states of a mixture of pseudospin-1 2 Bose gases with interspecies spin exchange." Modern Physics Letters B 30, no. 09 (April 10, 2016): 1650131. http://dx.doi.org/10.1142/s0217984916501311.

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Анотація:

In this paper, we analytically find the ground states of a mixture of two species of pseudospin-[Formula: see text] Bose gases with interspecies spin exchange in quite generic parameter regimes. In the most interesting phase, the ground state is strongly entangled between the two species in a very wide parameter regime, and is an entangled Bose-Einstein condensate. The phase diagram and elementary excitations are studied.

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19

REATTO, L., M. ROSSI, and D. E. GALLI. "BOSE–EINSTEIN CONDENSATION IN BULK AND CONFINED SOLID HELIUM." International Journal of Modern Physics B 20, no. 30n31 (December 20, 2006): 5081–92. http://dx.doi.org/10.1142/s0217979206036120.

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Анотація:

We address the question if the ground state of solid 4 He has the number of lattice sites equal to the number of atoms (commensurate state) or if it is different (incommensurate state). We point out that energy computation from simulation as performed by now cannot be used to decide this question and that the presently best variational wave function, a shadow wave function, gives an incommensurate state. We have extended the calculation of the one–body density matrix ρ1 to the exact Shadow Path Integral Ground State method. Calculation of ρ1 at ρ = 0.031 Å-3 shows that Vacancy–Interstitial pair processes are present also in the exact computation but the simulated system size is too small to infer the presence of off–diagonal long range order. Variational simulations of 4 He confined in a narrow cylindrical pore are also discussed.

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20

ZHAO, HUA, and J. Q. LIANG. "QUANTUM TUNNELING OF MESOSCOPIC SPIN IN BOSE–EINSTEIN CONDENSATES." International Journal of Modern Physics B 18, no. 08 (March 30, 2004): 1179–89. http://dx.doi.org/10.1142/s0217979204024471.

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Анотація:

In this paper the exact quantum phase model is derived with the help of a mesoscopic spin model from weakly linked two-component Bose–Einstein condensates. It is shown that the π-phase state which is seen to be the degenerate ground state exists only in an extreme limit of parameter, Δ≪1. π-phase state becomes metastable in the parameter region 0<Δ<1 and unstable when Δ≥1. The low-lying energy band resulted from the quantum tunneling is obtained explicitly by means of instanton method. We also analyze the phase-dissipation due to quantum tunneling. Moreover, the decay of the metastable π-phase state via quantum tunneling is studied and the life time is found analytically.

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21

GUO, YU, and RONG-SHENG QU. "QUANTUM TELEPORTATION FROM LIGHT TO ATOMIC BOSE–EINSTEIN CONDENSATE." Modern Physics Letters B 24, no. 10 (April 20, 2010): 937–44. http://dx.doi.org/10.1142/s0217984910022986.

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Анотація:

An optical scheme of the quantum teleportation of superposed coherent states from light pulse to the atoms in Bose–Einstein condensate in terms of optical elements is presented. Beam splitters, photodetectors, cross-Kerr medium, and coherent state sources are needed in this scheme. The probability of successful teleportation is also obtained.

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22

Li, Song-Song. "Generating entangled state of Bose–Einstein condensate using electromagnetically induced transparency." International Journal of Modern Physics B 32, no. 02 (January 16, 2018): 1830001. http://dx.doi.org/10.1142/s0217979218300013.

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Анотація:

We put forward a scheme on how to generate entangled state of Bose–Einstein condensate (BEC) using electromagnetically induced transparency (EIT). It is shown that we can rapidly generate the entangled state in the dynamical process and the entangled state maintained a long time interval. It is also shown that the better entangled state can be generated by decreasing coupling strengths of two classical laser fields, increasing two-photon detuning and total number of atoms.

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23

MA, YONG-LI, and HAICHEN ZHU. "A CLASS OF CLOSED SOLUTIONS FOR THE BOGOLIUBOV EXCITATIONS ON SMOOTH GROUND STATE OF A TRAPPED BOSE–EINSTEIN CONDENSATE." Modern Physics Letters B 19, no. 15 (June 30, 2005): 713–20. http://dx.doi.org/10.1142/s0217984905008670.

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Анотація:

Bogoliubov–de Gennes equations (BdGEs) for collective excitations from a trapped Bose–Einstein condensate described by a spatially smooth ground-state wavefunction can be treated analytically. A new class of closed solutions for the BdGEs is obtained for the one-dimensional (1D) and 3D spherically harmonic traps. The solutions of zero-energy mode of the BdGEs are also provided. The eigenfunctions of the excitations consist of zero-energy mode, zero-quantum-number mode and entire excitation modes when the approximate ground state is a background Bose gas sea.

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24

Zhao, Qiang. "Ground state of spin-2 dipolar rotating Bose–Einstein condensates." International Journal of Modern Physics B 33, no. 10 (April 20, 2019): 1950087. http://dx.doi.org/10.1142/s0217979219500875.

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Анотація:

We study the ground state of spin-2 dipolar rotating Bose–Einstein condensates in a harmonic potential. As the strength of dipolar interaction enhances, our results show that the vortex number becomes smaller and smaller at a fixed component. In addition, the vortex stripe occurs and its number increases. The components m[Formula: see text]1 or ±2 display the same density and the total density shows layered distribution. Increasing the rotational frequency to a higher value, the vortex number and vortex row number increase. We also plot the dependence of angular momentum Lz as a function of dipole strength c[Formula: see text], showing that Lz decreases with increasing c[Formula: see text].

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25

Mihalceanu, L., D. A. Bozhko, V. I. Vasyuchka, A. A. Serga, B. Hillebrands, A. Pomyalov, V. S. L'vov, and V. S. Tyberkevych. "Magnon Bose–Einstein Condensate and Supercurrents Over a Wide Temperature Range." Ukrainian Journal of Physics 64, no. 10 (November 1, 2019): 927. http://dx.doi.org/10.15407/ujpe64.10.927.

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Анотація:

Magnon Bose–Einstein Condensates (BECs) and supercurrents are coherent quantum phenomena, which appear on a macroscopic scale in parametrically populated solid state spin systems. One of the most fascinating and attractive features of these processes is the possibility of magnon condensation and supercurrent excitation even at room temperature. At the same time, valuable information about a magnon BEC state, such as its lifetime, its formation threshold, and coherence, is provided by experiments at various temperatures. Here, we use Brillouin Light Scattering (BLS) spectroscopy for the investigation of the magnon BEC dynamics in a single-crystal film of yttrium iron garnet in a wide temperature range from 30 K to 380K. By comparing the BLS results with previous microwave measurements, we revealed the direct relation between the damping of the condensed and the parametrically injected magnons. The enhanced supercurrent dynamics was detected at 180 K near the minimum of BEC damping.

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26

CHAUDHARY, G. K., AMIT K. CHATTOPADHYAY, and R. RAMAKUMAR. "BOSE–EINSTEIN CONDENSATE IN A QUARTIC POTENTIAL: STATIC AND DYNAMIC PROPERTIES." International Journal of Modern Physics B 25, no. 29 (November 20, 2011): 3927–40. http://dx.doi.org/10.1142/s0217979211101855.

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Анотація:

In this paper, we present a theoretical study of a Bose–Einstein condensate of interacting bosons in a quartic trap in one-, two- and three-dimensions. Using Thomas–Fermi approximation, suitably complemented by numerical solutions of the Gross–Pitaevskii equation, we study the ground-state condensate density profiles, the chemical potential, the effects of cross-terms in the quartic potential, temporal evolution of various energy components of the condensate and width oscillations of the condensate. Results obtained are compared with corresponding results for a bose condensate in a harmonic confinement.

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27

Stasyuk and Velychko. "Bose-Einstein condensation and/or modulation of "displacements" in the two-state Bose-Hubbard model." Condensed Matter Physics 21, no. 2 (June 2018): 23002. http://dx.doi.org/10.5488/cmp.21.23002.

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28

WU, CONGJUN. "UNCONVENTIONAL BOSE–EINSTEIN CONDENSATIONS BEYOND THE "NO-NODE" THEOREM." Modern Physics Letters B 23, no. 01 (January 10, 2009): 1–24. http://dx.doi.org/10.1142/s0217984909017777.

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Анотація:

Feynman's "no-node" theorem states that the conventional many-body ground state wavefunctions of bosons in the coordinate representation are positive definite. This implies that time-reversal symmetry cannot be spontaneously broken. In this article, we review our progress in studying a class of new states of unconventional Bose–Einstein condensations beyond this paradigm. These states can either be the long-lived metastable states of ultracold bosons in high orbital bands in optical lattices as a result of the "orbital Hund's rule" interaction, or the ground states of spinful bosons with spin-orbit coupling linearly dependent on momentum. In both cases, Feynman's argument does not apply. The resultant many-body wavefunctions are complex-valued and thus break time-reversal symmetry spontaneously. Exotic phenomena in these states include the Bose–Einstein condensation at nonzero momentum, the ordering of orbital angular momentum moments, the half-quantum vortex, and the spin texture of skyrmions.

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29

Chen, Lei, Xingran Xu, Shuai Kang, and Zhaoxin Liang. "Polariton Bose–Einstein condensate with spatially periodic interaction." Modern Physics Letters B 33, no. 31 (November 10, 2019): 1950382. http://dx.doi.org/10.1142/s0217984919503822.

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Анотація:

Recently, there are several experiments demonstrating the possibility to tune the interaction constants using biexcitonic Feshbach resonance in resonantly created polariton condensate and single quantum well. Motivated by these experiments, we theoretically study the stationary state of a polariton condensate whose interatomic scattering length is periodically modulated with optical Feshbach resonance, which represents a novel kind of non-equilibrium superfluidity. In more detail, the spontaneous symmetry breaking of the spin degree of freedom induced by different loss rates of the linear polarizations are investigated based on driven-dissipative Gross–Pitaevskii equations coupled to the rate equation of a reservoir.

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30

Aguilera-Navarro, V. C., M. Fortes, and M. de Llano. "Cooper Pairing and Ladder Correlations in a BCS Ground State." International Journal of Modern Physics B 17, no. 18n20 (August 10, 2003): 3304–9. http://dx.doi.org/10.1142/s0217979203021757.

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Анотація:

A Bethe–Salpeter treatment of Cooper pairs (CPs) based on an ideal Fermi gas (IFG) "sea" produces unstable CPs if holes are not ignored. Stable CPs with damping emerge when the BCS ground state replaces the IFG, and are positive-energy, finite-lifetime resonances for nonzero center-of-mass momentum with a linear dispersion leading term. Bose–Einstein condensation of such pairs may thus occur in exactly two dimensions as it cannot with quadratic dispersion.

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31

LIU, JIN-MING, and YU-ZHU WANG. "THREE-MODE ENTANGLED STATE OF AN ATOMIC BOSE–EINSTEIN CONDENSATE IN A THREE-WELL POTENTIAL." International Journal of Modern Physics B 20, no. 03 (January 30, 2006): 277–85. http://dx.doi.org/10.1142/s0217979206033279.

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Анотація:

In this paper, we present a scheme to generate a three-mode entangled state of an atomic Bose–Einstein condensate in a symmetric three-well potential by using controlled atomic elastic collisions. Then, by means of the method for calculating the formation entanglement of two qubits, we obtain the analytic expressions of the residual entanglement of the three-mode BEC entangled state.

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32

Alon, Ofir E. "Solvable Model of a Generic Driven Mixture of Trapped Bose–Einstein Condensates and Properties of a Many-Boson Floquet State at the Limit of an Infinite Number of Particles." Entropy 22, no. 12 (November 26, 2020): 1342. http://dx.doi.org/10.3390/e22121342.

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Анотація:

A solvable model of a periodically driven trapped mixture of Bose–Einstein condensates, consisting of N1 interacting bosons of mass m1 driven by a force of amplitude fL,1 and N2 interacting bosons of mass m2 driven by a force of amplitude fL,2, is presented. The model generalizes the harmonic-interaction model for mixtures to the time-dependent domain. The resulting many-particle ground Floquet wavefunction and quasienergy, as well as the time-dependent densities and reduced density matrices, are prescribed explicitly and analyzed at the many-body and mean-field levels of theory for finite systems and at the limit of an infinite number of particles. We prove that the time-dependent densities per particle are given at the limit of an infinite number of particles by their respective mean-field quantities, and that the time-dependent reduced one-particle and two-particle density matrices per particle of the driven mixture are 100% condensed. Interestingly, the quasienergy per particle does not coincide with the mean-field value at this limit, unless the relative center-of-mass coordinate of the two Bose–Einstein condensates is not activated by the driving forces fL,1 and fL,2. As an application, we investigate the imprinting of angular momentum and its fluctuations when steering a Bose–Einstein condensate by an interacting bosonic impurity and the resulting modes of rotations. Whereas the expectation values per particle of the angular-momentum operator for the many-body and mean-field solutions coincide at the limit of an infinite number of particles, the respective fluctuations can differ substantially. The results are analyzed in terms of the transformation properties of the angular-momentum operator under translations and boosts, and as a function of the interactions between the particles. Implications are briefly discussed.

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33

Abdullin, Iskander G., and Vladimir A. Popov. "Boson dark matter halos with a dominant noncondensed component." Journal of Cosmology and Astroparticle Physics 2021, no. 11 (November 1, 2021): 055. http://dx.doi.org/10.1088/1475-7516/2021/11/055.

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Abstract We consider galaxy halos formed by dark matter bosons with mass in the range of about a few tens or hundreds eV. A major part of the particles is in a noncondensed state and described under the Thomas-Fermi approach. Derived equations are solved numerically to find the halo density profile. The noncondensed state is supported in the entire halo except compact gravitationally bounded Bose-Einstein condensates. Although the size of these compact objects, also known as Bose stars, depends on interactions between the particles, its upper limit is only about 100 astronomical units. The Bose stars collect the condensed bosons providing a density cusp avoidance in the halo as well as a natural mechanism to prevent overproduction of small halos. Clusters of the Bose stars can also contribute to the halo density profile. The model is analyzed by confronting its predictions with observations of galaxy rotation curves. We employ 22 low surface brightness galaxies and obtain that the model is consistent with the observational data when the particle mass is in the range above about 50 eV and the best fit corresponds to the mass m = 86 eV. This mass is appropriate for relic dark matter bosons, which decouple just after QCD phase transition.

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34

Bücker, Robert, Tarik Berrada, Sandrine van Frank, Jean-François Schaff, Thorsten Schumm, Jörg Schmiedmayer, Georg Jäger, Julian Grond, and Ulrich Hohenester. "Vibrational state inversion of a Bose–Einstein condensate: optimal control and state tomography." Journal of Physics B: Atomic, Molecular and Optical Physics 46, no. 10 (May 9, 2013): 104012. http://dx.doi.org/10.1088/0953-4075/46/10/104012.

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35

SA-YAKANIT, VIRULH, and WATTANA LIM. "GROUND STATE ENERGY OF BOSE-EINSTEIN CONDENSATION IN A DISORDERED SYSTEM." International Journal of Modern Physics B 22, no. 25n26 (October 20, 2008): 4398–406. http://dx.doi.org/10.1142/s0217979208050152.

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Анотація:

A modeled Bose system consisting of N particles with two-body interaction confined within volume V under inhomogeneity of the system is investigated using the Feynman path integral approach. The two-body interaction energy is assumed to be dependent on the two-parameter interacting strength a and the correlation length l. The inhomogeneity of the system or the porosity can be represented as density [Formula: see text] with interacting strength b and correlation length L. The mean field approximation on the two-body interaction in the Feynman path integrals representation is performed to obtain the one-body interaction. This approximation is equivalent to the Hartree approximation in the many-body electron gas problem. This approximation has shown that the calculation can be reduced to the effective one-body propagator. Performing the variational calculations, we obtain analytical results of the ground state energy which is in agreement with that from Bugoliubov's approach.

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36

Cárdenas-Castillo, Luis Fernando, and Arturo Camacho-Guardian. "Strongly Interacting Bose Polarons in Two-Dimensional Atomic Gases and Quantum Fluids of Polaritons." Atoms 11, no. 1 (December 29, 2022): 3. http://dx.doi.org/10.3390/atoms11010003.

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Polarons are quasiparticles relevant across many fields in physics: from condensed matter to atomic physics. Here, we study the quasiparticle properties of two-dimensional strongly interacting Bose polarons in atomic Bose–Einstein condensates and polariton gases. Our studies are based on the non-self consistent T-matrix approximation adapted to these physical systems. For the atomic case, we study the spectral and quasiparticle properties of the polaron in the presence of a magnetic Feshbach resonance. We show the presence of two polaron branches: an attractive polaron, a low-lying state that appears as a well-defined quasiparticle for weak attractive interactions, and a repulsive polaron, a metastable state that becomes the dominant branch at weak repulsive interactions. In addition, we study a polaron arising from the dressing of a single itinerant electron by a quantum fluid of polaritons in a semiconductor microcavity. We demonstrate the persistence of the two polaron branches whose properties can be controlled over a wide range of parameters by tuning the cavity mode.

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37

Zhao, Qiang. "Vortex states in rotating two-component dipolar Bose–Einstein condensates." International Journal of Modern Physics B 33, no. 10 (April 20, 2019): 1950080. http://dx.doi.org/10.1142/s0217979219500802.

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We consider the stationary state properties of pseudo-spin-1/2 rotating dipolar Bose–Einstein condensates (BECs) by numerical simulations of the Gross–Pitaevskii equation. Different vortex structures in each component are studied, depending on the competition between the dipole–dipole interactions (DDIs) and rotational. We also investigate the differences of vortex number in the two components, showing that anisotropic nature of DDIs plays a significant role in vortices formation process.

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38

Boudiar, Abid. "Possible Bose-Einstein Condensation of Polygonal Clusters in 2D-Materials." Solid State Phenomena 297 (September 2019): 204–8. http://dx.doi.org/10.4028/www.scientific.net/ssp.297.204.

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This study investigates the possibility of Bose-Einstein condensation (BEC) in 2D-nanoclusters. A ground state equilibrium structure involves the single phonon exchange approximation. At critical temperature, the specific heat, entropy, and free energy of the system can be determined. The results support the existence of BEC in nanoclusters, and they lead to predictions of the behaviour of 2Dmaterials at low temperatures.

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39

GALLI, D. E., and L. REATTO. "BOSE–EINSTEIN CONDENSATION AND EXCITATIONS IN SOLID 4He WITH VACANCIES." International Journal of Modern Physics B 17, no. 28 (November 10, 2003): 5243–53. http://dx.doi.org/10.1142/s0217979203020387.

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We have studied the ground state and excited state properties of solid 4 He on the basis of the variational shadow wave function technique (SWF), which allows for relaxation and delocalisation of vacancies. We have found that a finite concentration of vacancies, if present, induces Bose-Einstein condensation (BEC) of the atoms at density close to the T=0 K melting where vacancies are delocalised. No BEC is present in a perfect crystal or in a defected solid at higher densities. We have extended this technique to study longitudinal phonons in solid 4 He and to study the vacancy excitation at a finite momentum; we have been able to compute for the first time the vacancy excitation spectrum in solid 4 He at density close to melting. Our results give a band width of about 8 K.

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40

Mullin, W. J., and F. Laloë. "Creation of NOON States from Double Fock-State/Bose-Einstein Condensates." Journal of Low Temperature Physics 162, no. 3-4 (October 9, 2010): 250–57. http://dx.doi.org/10.1007/s10909-010-0234-z.

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41

ISOBE, MASAHARU. "GRANULAR TURBULENCE IN TWO DIMENSIONS: MICROSCALE REYNOLDS NUMBER AND FINAL CONDENSED STATES." International Journal of Modern Physics C 23, no. 04 (April 2012): 1250032. http://dx.doi.org/10.1142/s0129183112500325.

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Granular gases from the viewpoint of "two-dimensional turbulence" are investigated. In the quasi-elastic and thermodynamic limit, we obtained clear evidence for an enstrophy (square of vorticity) cascade and -3 exponent in the Kraichnan–Leith–Bachelor energy spectrum by performing large-scale (N ~ 16.8 million number of disks) event-driven molecular dynamics simulations. In these calculations, the enstrophy dissipation rate showed a strong relationship with the evolution of the exponent in the energy spectrum. The growth of the Reynolds number based on the microscale confirmed that the enstrophy cascade regime was that of fully developed turbulence. Moreover, a condensed state resembling Bose–Einstein condensation in decaying two-dimensional Navier–Stokes turbulence also appeared as the final attractor of the evolving granular gas in the long time limit.

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42

R-MONTEIRO, M., ITZHAK RODITI та LIGIA M. C. S. RODRIGUES. "ν-DIMENSIONAL IDEAL QUANTUM q-GAS: BOSE-EINSTEIN CONDENSATION AND λ-POINT TRANSITION". International Journal of Modern Physics B 08, № 23 (20 жовтня 1994): 3281–98. http://dx.doi.org/10.1142/s0217979294001378.

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We consider an ideal quantum q-gas in ν spatial dimensions and energy spectrum ωiα pα Departing from the Hamiltonian H=ω[N], we study the effect of the deformation on thermodynamic functions and equation of state of that system. The virial expansion is obtained for the high temperature (or low density) regime. The critical temperature is higher than in non-deformed ideal gases. We show that Bose-Einstein condensation always exists (unless when ν/α=1) for finite q but not for q=∞. Employing numerical calculations and selecting for v/α the values 3/2, 2 and 3, we show the critical temperature as a function of q, the specific heat CV and the chemical potential µ as functions of [Formula: see text] for q=1.05 and q=4.5. CV exhibits a λ-point discontinuity in all cases, instead of the cusp singularity found in the usual ideal gas. Our results indicate that physical systems which have quantum symmetries can exhibit Bose-Einstein condensation phenomenon, the critical temperature being favored by the deformation parameter.

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43

Abbas, Karima, and Abdelâali Boudjemâa. "Binary Bose–Einstein condensates in a disordered time-dependent potential." Journal of Physics: Condensed Matter 34, no. 12 (January 10, 2022): 125102. http://dx.doi.org/10.1088/1361-648x/ac44d3.

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Abstract We study the non-equilibrium evolution of binary Bose–Einstein condensates in the presence of a weak random potential with Gaussian correlation function using the time-dependent perturbation theory. We apply this theory to construct a closed set of equations that highlight the role of the spectacular interplay between the disorder and the interspecies interactions in the time evolution of the density induced by disorder in each component. It is found that this latter increases with time favoring localization of both species. The time scale at which the theory remains valid depends on the respective system parameters. We show analytically and numerically that such a system supports a steady state that periodically changing during its time propagation. The obtained dynamical corrections indicate that disorder may transform the system into a stationary out-of-equilibrium states. Understanding this time evolution is pivotal for the realization of Floquet condensates.

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44

Wang, Ji-Guo, Yue-Qing Li, and Shi-Jie Yang. "Ground-state phase diagrams in spin–orbit coupled spin-3 Bose–Einstein condensates." Physica A: Statistical Mechanics and its Applications 597 (July 2022): 127244. http://dx.doi.org/10.1016/j.physa.2022.127244.

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45

Hartman, S. T. H., H. A. Winther, and D. F. Mota. "Constraints on self-interacting Bose-Einstein condensate dark matter using large-scale observables." Journal of Cosmology and Astroparticle Physics 2022, no. 02 (February 1, 2022): 005. http://dx.doi.org/10.1088/1475-7516/2022/02/005.

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Abstract Constraints on the cosmic history of self-interacting Bose-Einstein condensed (SIBEC) dark matter (DM) are obtained using the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO), growth factor measurements, and type Ia supernovae (SNIa) distances. Four scenarios are considered, one with purely SIBEC-DM, and three in which SIBEC-DM is the final product of some transition from different initial states, which are either cold, warm, or has a constant equation of state. Using a fluid approximation for the self-interacting scalar field it is found that in the simplest scenario of purely SIBEC-DM the self-interaction necessary for solving the cusp-core problem, with core-radii of low-mass halos of order R c ≳ 1kpc, is excluded at 2.4σ, or 98.5% confidence. Introducing a transition, however, relaxes this constraint, but the transitions are preferred to be after matter-radiation equality, and the initial phase to be cold.

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46

MAGPANTAY, JOSE A. "THERMODYNAMICS AND EXTRA DIMENSIONS." Modern Physics Letters B 23, no. 13 (May 30, 2009): 1625–32. http://dx.doi.org/10.1142/s0217984909019788.

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We consider the effects of extra dimensions on the thermodynamics of classical ideal gases, Bose–Einstein gases and Fermi–Dirac gas. Assuming a q-dimensional torus for the extra dimensions, we compute the thermodynamic functions such as the equation of state, the average energy and the specific heat at constant volume for the three systems. We show that the corrections due to the extra dimensions are small, proportional to [Formula: see text].

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47

Ardila, Luis A. Peña. "Ultra-Dilute Gas of Polarons in a Bose–Einstein Condensate." Atoms 10, no. 1 (March 2, 2022): 29. http://dx.doi.org/10.3390/atoms10010029.

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We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.

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48

Wang, Wei, and Jinbin Li. "Anisotropic properties of phase separation in two-component dipolar Bose–Einstein condensates." Modern Physics Letters B 32, no. 09 (March 30, 2018): 1850021. http://dx.doi.org/10.1142/s0217984918500215.

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Анотація:

Using Crank–Nicolson method, we calculate ground state wave functions of two-component dipolar Bose–Einstein condensates (BECs) and show that, due to dipole–dipole interaction (DDI), the condensate mixture displays anisotropic phase separation. The effects of DDI, inter-component s-wave scattering, strength of trap potential and particle numbers on the density profiles are investigated. Three types of two-component profiles are present, first cigar, along z-axis and concentric torus, second pancake (or blood cell), in xy-plane, and two non-uniform ellipsoid, separated by the pancake and third two dumbbell shapes.

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49

TEWARI, SHRI PRAKASH, POONAM SILOTIA, ADITYA SAXENA, and LOKESH KUMAR GUPTA. "EFFECT OF HIGHER ORDER ENERGY CORRECTIONS INCLUDING THREE-BODY INTERACTION ON THE BOSE-EINSTEIN CONDENSATE WITH THE VARIATION OF REPULSIVE SELF INTERACTION ENERGY." International Journal of Modern Physics B 20, no. 11n13 (May 20, 2006): 1690–98. http://dx.doi.org/10.1142/s0217979206034224.

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Various ground state properties such as chemical potential, differential and total energy per particle etc. of Bose-Einstein condensate of 10000 85 Rb atoms with varying repulsive self-interaction energy have been reported considering not only two-body interaction but also including the higher order terms of the low-density energy expansion of homogeneous Bose gas in the Ginzburg, Pitaevskii and Gross (GPG) equation. These include hard-core approximation of the bosons neglected earlier and the three-body interaction terms. The study is more general as it includes the terms beyond logarithm in energy density expansion. It is also shown that such a consideration does not violate the lower bound predicted earlier in which the 'constant' beyond logarithm term in the three-body interaction was neglected.

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50

Jankó, Boldizsár, Ioan Kosztin, and K. Levin. "Pseudogap Regime in a BCS Bose–Einstein Crossover Scenario: Experimental Consequences and Tests." International Journal of Modern Physics B 12, no. 29n31 (December 20, 1998): 3009–15. http://dx.doi.org/10.1142/s0217979298001964.

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We have argued that the pseudogap regime in the cuprates is characterized by the presence of metastable, long lived pairs which form the natural intermediate state between the free fermions of the BCS and bound pairs of the Bose Einstein limits. Here we investigate the experimental consequences associated with this resonant pair scattering in the normal state. The essential feature of these pair resonances is that they are dynamic pairing fluctuations. Of particular interest in distinguishing different scenarios for the cuprate pseudogap are probes which predominantly couple to the static and dynamic pair fluctuations, respectively. We therefore contrast the behavior of the diamagnetic susceptibility with the pair tunneling spectra of Superconductor-Pseudogapped cuprate junctions.

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