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Sample records for attractively interacting bose-einstein

  1. Bose-Einstein condensates with attractive 1/r interaction: The case of self-trapping

    SciTech Connect

    Papadopoulos, I.; Wagner, P.; Wunner, G.; Main, J.

    2007-11-15

    Amplifying on a proposal by O'Dell et al. for the realization of Bose-Einstein condensates of neutral atoms with attractive 1/r interaction, we point out that the instance of self-trapping of the condensate, without an external trap potential, is physically best understood by introducing appropriate 'atomic' units. This reveals a remarkable scaling property: the physics of the condensate depends only on the two parameters N{sup 2}a/a{sub u} and {gamma}/N{sup 2}, where N is the particle number, a the scattering length, a{sub u} the 'Bohr' radius, and {gamma} the trap frequency in atomic units. We calculate accurate numerical results for self-trapping wave functions and potentials, and for energies, sizes, and peak densities, and compare with previous variational results. We point out the existence of a second solution of the extended Gross-Pitaevskii equation for negative scattering lengths, with and without trapping potential, which is born together with the ground state in a tangent bifurcation. This indicates the existence of an unstable collectively excited state of the condensate for negative scattering lengths.

  2. Collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri

    2016-10-01

    We study the collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction. Equilibrium states in which the gravitational attraction and the attraction due to the self-interaction are counterbalanced by the quantum pressure (Heisenberg's uncertainty principle) exist only below a maximum mass Mmax=1.012 ℏ/√{G m |as| } where as<0 is the scattering length of the bosons and m is their mass [P. H. Chavanis, Phys. Rev. D 84, 043531 (2011)]. For M >Mmax the system is expected to collapse and form a black hole. We study the collapse dynamics by making a Gaussian ansatz for the wave function and reducing the problem to the study of the motion of a particle in an effective potential. We find that the collapse time scales as (M /Mmax-1 )-1 /4 for M →Mmax+ and as M-1 /2 for M ≫Mmax. Other analytical results are given above and below the critical point corresponding to a saddle-node bifurcation. We apply our results to QCD axions with mass m =10-4 eV /c2 and scattering length as=-5.8 ×10-53 m for which Mmax=6.5 ×10-14M⊙ and R =3.3 ×10-4R⊙. We confirm our previous claim that bosons with attractive self-interaction, such as QCD axions, may form low mass stars (axion stars or dark matter stars) but cannot form dark matter halos of relevant mass and size. These mini axion stars could be the constituents of dark matter. They can collapse into mini black holes of mass ˜10-14M⊙ in a few hours. In that case, dark matter halos would be made of mini black holes. We also apply our results to ultralight axions with mass m =1.93 ×10-20 eV /c2 and scattering length as=-8.29 ×10-60 fm for which Mmax=0.39 ×1 06M⊙ and R =33 pc . These ultralight axions could cluster into dark matter halos. Axionic dark matter halos with attractive self-interaction can collapse into supermassive black holes of mass ˜1 06M⊙ (similar to those reported at the center of galaxies) in about one million years. We point out the limitations of the Gaussian ansatz to

  3. Criterion for Bose-Einstein condensation in a harmonic trap in the case with attractive interactions

    SciTech Connect

    Gajda, Mariusz

    2006-02-15

    Using a model many-body wave function I analyze the standard criterion for Bose-Einstein condensation and its relation to coherence properties of the system. I pay special attention to an attractive condensate under such a condition that a characteristic length scale of the spatial extension of its center of mass differs significantly from length scales of relative coordinates. I show that although no interference fringes are produced in the two-slit Young interference experiment performed on this system, fringes of a high visibility can be observed in a conditional simultaneous detection of two particles.

  4. Split-merge cycle, fragmented collapse, and vortex disintegration in rotating Bose-Einstein condensates with attractive interactions

    SciTech Connect

    Saito, Hiroki; Ueda, Masahito

    2004-01-01

    The dynamical instabilities and ensuing dynamics of singly and doubly quantized vortex states of Bose-Einstein condensates with attractive interactions are investigated using full three-dimensional numerical simulations of the Gross-Pitaevskii equation. With increasing the strength of attractive interactions, a series of dynamical instabilities such as quadrupole, dipole, octupole, and monopole instabilities emerge. The most prominent instability depends on the strength of interactions, the geometry of the trapping potential, and deviations from the axisymmetry due to external perturbations. Singly quantized vortices split into two clusters and subsequently undergo split-merge cycles in a pancake-shaped trap, whereas the split fragments immediately collapse in a spherical trap. Doubly quantized vortices are always unstable to disintegration of the vortex core. If we suddenly change the strength of interaction to within a certain range, the vortex splits into three clusters, and one of the clusters collapses after a few split-merge cycles. The vortex split can be observed using a current experimental setup of Leanhardt et al. [Phys. Rev. Lett. 89, 190403 (2002)].

  5. Split instability of a vortex in an attractive Bose-Einstein condensate.

    PubMed

    Saito, Hiroki; Ueda, Masahito

    2002-11-04

    An attractive Bose-Einstein condensate with a vortex splits into two pieces via the quadrupole dynamical instability, which arises at a weaker strength of interaction than the monopole and the dipole instabilities. The split pieces subsequently unite to restore the original vortex or collapse.

  6. Collapse of attractive Bose-Einstein condensed vortex states in a cylindrical trap.

    PubMed

    Adhikari, Sadhan K

    2002-01-01

    The quantized vortex states of a weakly interacting Bose-Einstein condensate of atoms with attractive interatomic interaction in an axially symmetric harmonic oscillator trap are investigated using the numerical solution of the time-dependent Gross-Pitaevskii equation obtained by the semi-implicit Crank-Nicholson method. The collapse of the condensate is studied in the presence of deformed traps with the larger frequency along either the radial or the axial direction. The critical number of atoms for collapse is calculated as a function of the vortex quantum number L. The critical number increases with increasing angular momentum L of the vortex state but tends to saturate for large L.

  7. Competition between attractive and repulsive interactions in two-component Bose-Einstein condensates trapped in an optical lattice

    SciTech Connect

    Matuszewski, Michal; Malomed, Boris A.; Trippenbach, Marek

    2007-10-15

    We consider effects of interspecies attraction on two-component gap solitons (GSs) in the binary BEC with intraspecies repulsion, trapped in the one-dimensional optical lattice (OL). Systematic simulations of the coupled Gross-Pitaevskii equations corroborate an assumption that, because the effective mass of GSs is negative, the interspecies attraction may split the two-component soliton. Two critical values, {kappa}{sub 1} and {kappa}{sub 2}, of the OL strength ({kappa}) are identified. Two-species GSs with fully overlapping wave functions are stable in strong lattices ({kappa}>{kappa}{sub 1}). In an intermediate region, {kappa}{sub 1}>{kappa}>{kappa}{sub 2}, the soliton splits into a double-humped state with separated components. Finally, in weak lattices ({kappa}<{kappa}{sub 2}), the splitting generates a pair of freely moving single-species GSs. We present and explain the dependence of {kappa}{sub 1} and {kappa}{sub 2} on the number of atoms (total norm), and on the relative strength of the competing interspecies attraction and intraspecies repulsion. The splitting of asymmetric solitons, with unequal norms of the two species, is briefly considered too. It is found and explained that the splitting threshold grows with the increase of the asymmetry.

  8. Existence and mass concentration of 2D attractive Bose-Einstein condensates with periodic potentials

    NASA Astrophysics Data System (ADS)

    Wang, Qingxuan; Zhao, Dun

    2017-02-01

    In this paper we consider a two-dimensional attractive Bose-Einstein condensate with periodic potential, described by Gross-Pitaevskii (GP) functional. By concentration-compactness lemma we show that minimizers of this functional exist when the interaction strength a satisfies a* < a 0, and there is no minimizer for a ≥a*. When a approaches a*, using concentration-compactness arguments again we obtain an optimal energy estimate depending on the shape of periodic potential. Moreover, we analyze the mass concentration.

  9. Double species Bose-Einstein condensate with tunable interspecies interactions.

    PubMed

    Thalhammer, G; Barontini, G; De Sarlo, L; Catani, J; Minardi, F; Inguscio, M

    2008-05-30

    We produce Bose-Einstein condensates of two different species, 87Rb and 41K, in an optical dipole trap in proximity of interspecies Feshbach resonances. We discover and characterize two Feshbach resonances, located around 35 and 79 G, by observing the three-body losses and the elastic cross section. The narrower resonance is exploited to create a double species condensate with tunable interactions. Our system opens the way to the exploration of double species Mott insulators and, more in general, of the quantum phase diagram of the two-species Bose-Hubbard model.

  10. Dynamics of vortices in weakly interacting Bose-Einstein condensates

    SciTech Connect

    Klein, Alexander; Jaksch, Dieter; Zhang Yanzhi; Bao Weizhu

    2007-10-15

    We study the dynamics of vortices in ideal and weakly interacting Bose-Einstein condensates using a Ritz minimization method to solve the two-dimensional Gross-Pitaevskii equation. For different initial vortex configurations we calculate the trajectories of the vortices. We find conditions under which a vortex-antivortex pair annihilates and is created again. For the case of three vortices we show that at certain times two additional vortices may be created, which move through the condensate and annihilate each other again. For a noninteracting condensate this process is periodic, whereas for small interactions the essential features persist, but the periodicity is lost. The results are compared to exact numerical solutions of the Gross-Pitaevskii equation confirming our analytical findings.

  11. 85Rb tunable-interaction Bose-Einstein condensate machine

    NASA Astrophysics Data System (ADS)

    Altin, P. A.; Robins, N. P.; Döring, D.; Debs, J. E.; Poldy, R.; Figl, C.; Close, J. D.

    2010-06-01

    We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of R85b with tunable interparticle interactions. We use sympathetic cooling with R87b in two stages, initially in a tight Ioffe-Pritchard magnetic trap and subsequently in a weak, large-volume, crossed optical dipole trap, using the 155 G Feshbach resonance to manipulate the elastic and inelastic scattering properties of the R85b atoms. Typical R85b condensates contain 4×104 atoms with a scattering length of a =+200a0. Many aspects of the design presented here could be adapted to other dual-species BEC machines, including those involving degenerate Fermi-Bose mixtures. Our minimalist apparatus is well suited to experiments on dual-species and spinor Rb condensates, and has several simplifications over the R85b BEC machine at JILA, which we discuss at the end of this article.

  12. Collapse of the metastable state in an attractive Bose-Einstein condensate.

    PubMed

    Kim, Jae Gil; Choi, Yoon-Hyuck Sean; Lee, Eok Kyun

    2002-07-01

    The characteristic features of the collapse of the ground state in trapped one-component attractive Bose-Einstein condensates are studied by applying the catastrophe theory. From numerically obtained stable and unstable solutions of the Gross-Pitaevskii equation, we derive the catastrophe function defining the stability of the stationary points on the Gross-Pitaevskii energy functional. The bifurcation diagram and the universal scaling laws stemming from the catastrophe function show quantitative agreement with the numerical results.

  13. Harmonically trapped attractive and repulsive spin-orbit and Rabi coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Chiquillo, Emerson

    2017-03-01

    Numerically we investigate the ground state of effective one-dimensional spin-orbit (SO) and Rabi coupled two pseudo-spinor Bose-Einstein condensates (BECs) under the effect of harmonic traps. For both signs of the interaction, density profiles of SO and Rabi coupled BECs in harmonic potentials, which simulate a real experimental situation are obtained. The harmonic trap causes a strong reduction of the multi-peak nature of the condensate and it increases its density. For repulsive interactions, the increase of SO coupling results in an uncompressed less dense condensate and with increased multi-peak nature of the density. The increase of Rabi coupling leads to a density increase with an almost constant number of multi-peaks. For both signs of the interaction and negative values of Rabi coupling, the condensate develops a notch in the central point and it seems to a dark-in-bright soliton. In the case of the attractive nonlinearity, an interesting result is the increase of the collapse threshold under the action of the SO and Rabi couplings.

  14. Vortex lattices in planar Bose-Einstein condensates with dipolar interactions.

    PubMed

    Zhang, Jian; Zhai, Hui

    2005-11-11

    In this Letter, we investigate the effects of dipole-dipole interactions on the vortex lattices in fast rotating Bose-Einstein condensates. For single planar condensate, we show that the triangular lattice structure will be unfavorable when the s-wave interaction is attractive and exceeds a critical value. It will first change to a square lattice, and then become more and more flat with the increase of s-wave attraction, until the collapse of the condensate. For an array of coupled planar condensates, we discuss how the dipole-dipole interactions between neighboring condensates compete with quantum tunneling processes, which affects the relative displacement of two neighboring vortex lattices and leads to the loss of phase coherence between different condensates.

  15. Vortex Lattices in Planar Bose-Einstein Condensates with Dipolar Interactions

    SciTech Connect

    Zhang Jian; Zhai Hui

    2005-11-11

    In this Letter, we investigate the effects of dipole-dipole interactions on the vortex lattices in fast rotating Bose-Einstein condensates. For single planar condensate, we show that the triangular lattice structure will be unfavorable when the s-wave interaction is attractive and exceeds a critical value. It will first change to a square lattice, and then become more and more flat with the increase of s-wave attraction, until the collapse of the condensate. For an array of coupled planar condensates, we discuss how the dipole-dipole interactions between neighboring condensates compete with quantum tunneling processes, which affects the relative displacement of two neighboring vortex lattices and leads to the loss of phase coherence between different condensates.

  16. Stability and decay rates of nonisotropic attractive Bose-Einstein condensates

    SciTech Connect

    Huepe, C.; Tuckerman, L. S.; Metens, S.; Brachet, M. E.

    2003-08-01

    Nonisotropic attractive Bose-Einstein condensates are investigated numerically with Newton and inverse Arnoldi methods. The stationary solutions of the Gross-Pitaevskii equation and their linear stability are computed. Bifurcation diagrams are calculated and used to find the condensate decay rates corresponding to macroscopic quantum tunneling, two-three-body inelastic collisions, and thermally induced collapse. Isotropic and nonisotropic condensates are compared. The effect of anisotropy on the bifurcation diagram and the decay rates is discussed. Spontaneous isotropization of the condensates is found to occur. The influence of isotropization on the decay rates is characterized near the critical point.

  17. Nonlinear Dynamics of Bose-Einstein Condensates with Long-Range Interactions

    SciTech Connect

    Wunner, G.; Cartarius, H.; Fabcic, T.; Koeberle, P.; Main, J.; Schwidder, T.

    2008-11-13

    The motto of this paper is: Let's face Bose-Einstein condensation through nonlinear dynamics. We do this by choosing variational forms of the condensate wave functions (of given symmetry classes), which convert the Bose-Einstein condensates via the time-dependent Gross-Pitaevskii equation into Hamiltonian systems that can be studied using the methods of nonlinear dynamics. We consider in particular cold quantum gases where long-range interactions between the neutral atoms are present, in addition to the conventional short-range contact interaction, viz. gravity-like interactions, and dipole-dipole interactions. The results obtained serve as a useful guide in the search for nonlinear dynamics effects in numerically exact quantum calculations for Bose-Einstein condensates. A main result is the prediction of the existence of stable islands as well as chaotic regions for excited states of dipolar condensates, which could be checked experimentally.

  18. Localized modes in dense repulsive and attractive Bose-Einstein condensates with spin-orbit and Rabi couplings

    NASA Astrophysics Data System (ADS)

    Salasnich, Luca; Malomed, Boris A.

    2013-06-01

    We consider a binary Bose-Einstein condensate with linear and nonlinear interactions between its components, which emulate the spinor system with spin-orbit (SO) and Rabi couplings. For a relatively dense condensate, one-dimensional coupled equations with the nonpolynomial nonlinearity of both repulsive and attractive signs are derived from the three-dimensional Gross-Pitaevskii equations. Profiles of modes confined in an external potential under the action of the self-repulsion, and self-trapped solitons in the case of the self-attraction, are found in a numerical form and by means of analytical approximations. In the former case, the interplay of the SO and Rabi couplings with the repulsive nonlinearity strongly distorts shapes of the trapped modes, adding conspicuous sidelobes to them. In the case of the attractive nonlinearity, the most essential result is reduction of the collapse threshold under the action of the SO and Rabi couplings.

  19. Interaction effects on number fluctuations in a Bose-Einstein condensate of light.

    PubMed

    van der Wurff, E C I; de Leeuw, A-W; Duine, R A; Stoof, H T C

    2014-09-26

    We investigate the effect of interactions on condensate-number fluctuations in Bose-Einstein condensates. For a contact interaction we variationally obtain the equilibrium probability distribution for the number of particles in the condensate. To facilitate comparison with experiment, we also calculate the zero-time delay autocorrelation function g((2))(0) for different strengths of the interaction. Finally, we focus on the case of a condensate of photons and find good agreement with recent experiments.

  20. Magnon-magnon interactions in a room-temperature magnonic Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Dzyapko, Oleksandr; Lisenkov, Ivan; Nowik-Boltyk, Patrik; Demidov, Vladislav E.; Demokritov, Sergej O.; Koene, Benny; Kirilyuk, Andrei; Rasing, Theo; Tiberkevich, Vasyl; Slavin, Andrei

    2017-08-01

    The Bose-Einstein condensate of magnons (mBEC) that is formed at room temperature in parametrically pumped magnetic films is doubly degenerate: it is formed simultaneously in two spectral minima corresponding to the lowest-energy magnons propagating in opposite directions along the in-plane bias magnetic field. In this work the interactions of magnons in the mBEC are studied both theoretically and experimentally. It is shown by direct calculation that the magnons residing in each of the degenerate spectral minima of mBEC form a practically ideal magnon gas, as the attractive self-interaction between these magnons is very weak. At the same time, the interaction between the magnons residing in different spectral minima, corresponding to opposite directions of the magnon wave vector, is relatively strong and repulsive, leading to a repulsive total intermagnon interaction. By measuring the spectral characteristics of the mBEC it is shown that with increased magnon density the energy per magnon in the mBECs increases, thus confirming experimentally that the net intermagnon interaction in a doubly degenerate mBEC is repulsive.

  1. Elementary excitations and universal interaction in Bose-Einstein condensates at large scattering lengths

    SciTech Connect

    Sarjonen, R.; Saarela, M.; Mazzanti, F.

    2011-10-15

    We present a theoretical analysis of excitation modes in Bose-Einstein condensates of ultracold alkali-metal gases for large scattering lengths, showing clear deviations from the Bogoliubov prediction as seen by Papp et al.[Phys. Rev. Lett. 101, 135301 (2008)]. We construct the atom-atom interaction by deriving the T matrix of such systems from two coupled (open and closed) channels assuming that the Feshbach resonance dominates the latter. We calculate molecular bound-state energies as a function of the magnetic field and compare with available experiments. The s-wave phase shifts determine the local effective interaction with long-ranged repulsion and short-ranged attraction. We show that it becomes a universal function at large scattering lengths. Finally, we use this interaction to characterize the ground-state and elementary excitations of {sup 85}Rb, {sup 87}Rb, and {sup 23}Na gases. Good agreement with line shift experiments in {sup 85}Rb is achieved. We find that, at large scattering lengths, Bragg scattering experiments could directly measure the momentum dependence of the effective two-body potential.

  2. Elementary excitations and universal interaction in Bose-Einstein condensates at large scattering lengths

    NASA Astrophysics Data System (ADS)

    Sarjonen, R.; Saarela, M.; Mazzanti, F.

    2011-10-01

    We present a theoretical analysis of excitation modes in Bose-Einstein condensates of ultracold alkali-metal gases for large scattering lengths, showing clear deviations from the Bogoliubov prediction as seen by Papp [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.101.135301 101, 135301 (2008)]. We construct the atom-atom interaction by deriving the T matrix of such systems from two coupled (open and closed) channels assuming that the Feshbach resonance dominates the latter. We calculate molecular bound-state energies as a function of the magnetic field and compare with available experiments. The s-wave phase shifts determine the local effective interaction with long-ranged repulsion and short-ranged attraction. We show that it becomes a universal function at large scattering lengths. Finally, we use this interaction to characterize the ground-state and elementary excitations of 85Rb, 87Rb, and 23Na gases. Good agreement with line shift experiments in 85Rb is achieved. We find that, at large scattering lengths, Bragg scattering experiments could directly measure the momentum dependence of the effective two-body potential.

  3. Induced interaction and crystallization of self-localized impurity fields in a Bose-Einstein condensate

    SciTech Connect

    Rica, Sergio; Roberts, David C.

    2009-07-15

    We model the behavior of N classical impurity fields immersed in a larger Bose-Einstein condensate by N+1 coupled nonlinear Schroedinger equations in one, two, and three space dimensions. We discuss the stability of the uniform miscible system and show the importance of surface tension for self-localization of the impurity fields. We derive analytically the attractive tail of the impurity-impurity interaction due to mediation by the underlying condensate. Assuming all impurity fields interact with the same strength, we explore numerically the resulting phase diagram, which contains four phases: (I) all fields are miscible; (II) the impurity fields are miscible with each other but phase separate from the condensate as a single bubble; (III) the localized impurity fields stay miscible with the condensate, but not with each other; and (IV) the impurity fields phase separate from the condensate and each other, forming a crystalline structure within a bubble. Thus, we show that a crystal can be constructed solely from superfluid components. Finally, we argue that the crystalline phases maintain their superfluid behavior, i.e., they possess a nonclassical rotational inertia, which - combined with lattice order - is a characteristic of supersolidity.

  4. Nearly-one-dimensional self-attractive Bose-Einstein condensates in optical lattices

    SciTech Connect

    Salasnich, L.; Toigo, F.; Cetoli, A.; Malomed, B. A.

    2007-03-15

    Within the framework of a mean-field description, we investigate atomic Bose-Einstein condensates, with attraction between atoms, under the action of a strong transverse confinement and periodic [optical-lattice (OL)] axial potential. Using a combination of the variational approximation, one-dimensional (1D) nonpolynomial Schroedinger equation, and direct numerical solutions of the underlying 3D Gross-Pitaevskii equation, we show that the ground state of the condensate is a soliton belonging to the semi-infinite band gap of the periodic potential. The soliton may be confined to a single cell of the lattice or extended to several cells, depending on the effective self-attraction strength g (which is proportional to the number of atoms bound in the soliton) and depth of the potential, V{sub 0}, the increase of V{sub 0} leading to strong compression of the soliton. We demonstrate that the OL is an effective tool to control the soliton's shape. It is found that, due to the 3D character of the underlying setting, the ground-state soliton collapses at a critical value of the strength, g=g{sub c}, which gradually decreases with the increase of V{sub 0}; under typical experimental conditions, the corresponding maximum number of {sup 7}Li atoms in the soliton, N{sub max}, ranges between 8000 and 4000. Examples of stable multipeaked solitons are also found in the first finite band gap of the lattice spectrum. The respective critical value g{sub c} again slowly decreases with the increase of V{sub 0}, corresponding to N{sub max}{approx_equal}5000.

  5. Instability of collective excitations and power laws of an attractive Bose-Einstein condensate in an anharmonic trap

    SciTech Connect

    Debnath, P. K.; Chakrabarti, Barnali

    2010-10-15

    We study the instability of collective excitations of a three-dimensional Bose-Einstein condensate with repulsive and attractive interactions in a shallow trap designed as a quadratic plus a quartic potential. By using a correlated many-body theory, we determine the excitation modes and probe the critical behavior of collective modes, having a crucial dependence on the anharmonic parameter. We examine the power-law behavior of monopole frequency near criticality. In Gross-Pitaevskii variational treatment [Phys. Rev. Lett. 80, 1576 (1998)] the power-law exponent is determined as one-fourth power of (1-(A/A{sub cr})), A is the number of condensate atoms and A{sub cr} is the critical number near collapse. We observe that the power-law exponent becomes (1/6) in our calculation for the pure harmonic trap and it becomes (1/7), for traps with a small anharmonic distortion. However for large anharmonicity the power law breaks down.

  6. Instability of collective excitations and power laws of an attractive Bose-Einstein condensate in an anharmonic trap

    NASA Astrophysics Data System (ADS)

    Debnath, P. K.; Chakrabarti, Barnali

    2010-10-01

    We study the instability of collective excitations of a three-dimensional Bose-Einstein condensate with repulsive and attractive interactions in a shallow trap designed as a quadratic plus a quartic potential. By using a correlated many-body theory, we determine the excitation modes and probe the critical behavior of collective modes, having a crucial dependence on the anharmonic parameter. We examine the power-law behavior of monopole frequency near criticality. In Gross-Pitaevskii variational treatment [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.80.1576 80, 1576 (1998)] the power-law exponent is determined as one-fourth power of (1-(A)/(Acr)), A is the number of condensate atoms and Acr is the critical number near collapse. We observe that the power-law exponent becomes (1)/(6) in our calculation for the pure harmonic trap and it becomes (1)/(7), for traps with a small anharmonic distortion. However for large anharmonicity the power law breaks down.

  7. Interactions and collisions of discrete breathers in two-species Bose-Einstein condensates in optical lattices.

    PubMed

    Campbell, Russell; Oppo, Gian-Luca; Borkowski, Mateusz

    2015-01-01

    The dynamics of static and traveling breathers in two-species Bose-Einstein condensates in a one-dimensional optical lattice is modelled within the tight-binding approximation. Two coupled discrete nonlinear Schrödinger equations describe the interaction of the condensates in two cases of relevance: a mixture of two ytterbium isotopes and a mixture of (87)Rb and (41)K. Depending on their initial separation, interaction between static breathers of different species can lead to the formation of symbiotic structures and transform one of the breathers from a static into a traveling one. Collisions between traveling and static discrete breathers composed of different species are separated into four distinct regimes ranging from totally elastic when the interspecies interaction is highly attractive to mutual destruction when the interaction is sufficiently large and repulsive. We provide an explanation of the collision features in terms of the interspecies coupling and the negative effective mass of the discrete breathers.

  8. Interactions and collisions of discrete breathers in two-species Bose-Einstein condensates in optical lattices

    NASA Astrophysics Data System (ADS)

    Campbell, Russell; Oppo, Gian-Luca; Borkowski, Mateusz

    2015-01-01

    The dynamics of static and traveling breathers in two-species Bose-Einstein condensates in a one-dimensional optical lattice is modelled within the tight-binding approximation. Two coupled discrete nonlinear Schrödinger equations describe the interaction of the condensates in two cases of relevance: a mixture of two ytterbium isotopes and a mixture of 87Rb and 41K. Depending on their initial separation, interaction between static breathers of different species can lead to the formation of symbiotic structures and transform one of the breathers from a static into a traveling one. Collisions between traveling and static discrete breathers composed of different species are separated into four distinct regimes ranging from totally elastic when the interspecies interaction is highly attractive to mutual destruction when the interaction is sufficiently large and repulsive. We provide an explanation of the collision features in terms of the interspecies coupling and the negative effective mass of the discrete breathers.

  9. Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates

    DTIC Science & Technology

    2015-06-23

    two setups have been constructed and operated towards these goals. In the first, a metal tip (diameter 125 microns) is mounted close to a magneto... metal tip (diameter 125 microns) is mounted close to a magneto-optic trap (MOT). Rydberg excitations are implanted in a cold-atom region (diameter...Rydberg-level shifts caused by image charge interaction near metal sur- faces [15, 16]. The van der Waals interaction between excited cesium atoms and a

  10. A Simple Model of Bose-Einstein Condensation of Interacting Particles

    NASA Astrophysics Data System (ADS)

    Poluektov, Yu. M.

    2017-03-01

    A simple model of Bose-Einstein condensation of interacting particles is proposed. It is shown that in the condensate state the dependence of thermodynamic quantities on the interaction constant does not allow an expansion in powers of the coupling constant. Therefore, it is impossible to pass to the Einstein model of condensation in an ideal Bose gas by means of a limiting passage, setting the interaction constant to zero. The account for the interaction between particles eliminates difficulties in the description of condensation available in the model of an ideal gas, which are connected with the fulfillment of thermodynamic relations and an infinite value of the particle number fluctuation in the condensate phase.

  11. Multimode Kapitza-Dirac interferometer on Bose-Einstein condensates with atomic interactions

    NASA Astrophysics Data System (ADS)

    He, Tianchen; Niu, Pengbin

    2017-03-01

    The dynamics of multimode interferometers for Bose Einstein condensation (BEC) with atomic interactions confined to a harmonic trap is investigated. At the initial time t = 0, several spatially addressable wave packets (modes) with different momenta are created by the first Kapitza-Dirac pulse. These modes are coherently recombined by the harmonic potential with atomic interactions. The second Kapitza-Dirac pulse splits the evolved modes a second time and separates them along different paths for a second time. The signal to noise ratio is numerically calculated by the Fisher information and the Cramér-Rao lower bound. We find that the small atomic interactions decrease the measurement accuracy for current atom interferometers when measuring the gravitational acceleration. Its impact on measurement precision can be reduced by improving the Kapitza-Dirac strength.

  12. Feedback control of an interacting Bose-Einstein condensate using phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Szigeti, S. S.; Hush, M. R.; Carvalho, A. R. R.; Hope, J. J.

    2010-10-01

    The linewidth of an atom laser is limited by density fluctuations in the Bose-Einstein condensate (BEC) from which the atom laser beam is outcoupled. In this paper we show that a stable spatial mode for an interacting BEC can be generated using a realistic control scheme that includes the effects of the measurement backaction. This model extends the feedback theory, based on a phase-contrast imaging setup, presented by Szigeti, Hush, Carvalho, and Hope [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.013614 80, 013614 (2009)]. In particular, it is applicable to a BEC with large interatomic interactions and solves the problem of inadequacy of the mean-field (coherent state) approximation by utilizing a fixed number state approximation. Our numerical analysis shows the control to be more effective for a condensate with a large nonlinearity.

  13. Rayleigh surface wave interaction with the 2D exciton Bose-Einstein condensate

    SciTech Connect

    Boev, M. V.; Kovalev, V. M.

    2015-06-15

    We describe the interaction of a Rayleigh surface acoustic wave (SAW) traveling on the semiconductor substrate with the excitonic gas in a double quantum well located on the substrate surface. We study the SAW attenuation and its velocity renormalization due to the coupling to excitons. Both the deformation potential and piezoelectric mechanisms of the SAW-exciton interaction are considered. We focus on the frequency and excitonic density dependences of the SAW absorption coefficient and velocity renormalization at temperatures both above and well below the critical temperature of Bose-Einstein condensation of the excitonic gas. We demonstrate that the SAW attenuation and velocity renormalization are strongly different below and above the critical temperature.

  14. Weakly interacting spinor Bose-Einstein condensates with three-dimensional spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Shu-Wei, Song; Rui, Sun; Hong, Zhao; Xuan, Wang; Bao-Zhong, Han

    2016-04-01

    Starting from the Hamiltonian of the second quantization form, the weakly interacting Bose-Einstein condensate with spin-orbit coupling of Weyl type is investigated. It is found that the SU(2) nonsymmetric term, i.e., the spin-dependent interaction, can lift the degeneracy of the ground states with respect to the z component of the total angular momentum J z , casting the ground condensate state into a configuration of zero J z . This ground state density profile can also be affirmed by minimizing the full Gross-Pitaevskii energy functional. The spin texture of the zero J z state indicates that it is a knot structure, whose fundamental group is π 3(M) ≅ π 3(S 2) = Z. Project supported by the National Natural Science Foundation of China (Grant No. 11447178).

  15. Bose-Einstein condensates with spatially inhomogeneous interaction and bright solitons

    NASA Astrophysics Data System (ADS)

    Shin, H. J.; Radha, R.; Kumar, V. Ramesh

    2011-06-01

    In this Letter, we investigate the dynamics of Bose-Einstein Condensates (BECs) with spatially inhomogeneous interaction and generate bright solitons for the condensates by solving the associated mean field description governed by the Gross-Pitaevskii (GP) equation. We then investigate the properties of BECs in an optical lattice and periodic potential. We show that the GP equation in an optical lattice potential is integrable provided the interaction strength between the atoms varies periodically in space. The model discussed in the Letter offers the luxury of choosing the form of the lattice without destroying the integrability. Besides, we have also brought out the possible ramifications of the integrable model in the condensates of quasi-particles.

  16. Quasiparticle Energy in a Strongly Interacting Homogeneous Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Lopes, Raphael; Eigen, Christoph; Barker, Adam; Viebahn, Konrad G. H.; Robert-de-Saint-Vincent, Martin; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P.

    2017-05-01

    Using two-photon Bragg spectroscopy, we study the energy of particlelike excitations in a strongly interacting homogeneous Bose-Einstein condensate, and observe dramatic deviations from Bogoliubov theory. In particular, at large scattering length a the shift of the excitation resonance from the free-particle energy changes sign from positive to negative. For an excitation with wave number q , this sign change occurs at a ≈4 /(π q ) , in agreement with the Feynman energy relation and the static structure factor expressed in terms of the two-body contact. For a ≳3 /q we also see a breakdown of this theory, and better agreement with calculations based on the Wilson operator product expansion. Neither theory explains our observations across all interaction regimes, inviting further theoretical efforts.

  17. Long-lived periodic revivals of coherence in an interacting Bose-Einstein condensate

    SciTech Connect

    Egorov, M.; Ivannikov, V.; Opanchuk, B.; Drummond, P.; Hall, B. V.; Sidorov, A. I.; Anderson, R. P.

    2011-08-15

    We observe the coherence of an interacting two-component Bose-Einstein condensate (BEC) surviving for seconds in a trapped Ramsey interferometer. Mean-field-driven collective oscillations of two components lead to periodic dephasing and rephasing of condensate wave functions with a slow decay of the interference fringe visibility. We apply spin echo synchronous with the self-rephasing of the condensate to reduce the influence of state-dependent atom losses, significantly enhancing the visibility up to 0.75 at the evolution time of 1.5 s. Mean-field theory consistently predicts higher visibility than experimentally observed values. We quantify the effects of classical and quantum noise and infer a coherence time of 2.8 s for a trapped condensate of 5.5x10{sup 4} interacting atoms.

  18. Dynamics and Interaction of Vortex Lines in an Elongated Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Serafini, S.; Barbiero, M.; Debortoli, M.; Donadello, S.; Larcher, F.; Dalfovo, F.; Lamporesi, G.; Ferrari, G.

    2015-10-01

    We study the real-time dynamics of vortices in a large elongated Bose-Einstein condensate (BEC) of sodium atoms using a stroboscopic technique. Vortices are produced via the Kibble-Zurek mechanism in a quench across the BEC transition and they slowly precess keeping their orientation perpendicular to the long axis of the trap as expected for solitonic vortices in a highly anisotropic condensate. Good agreement with theoretical predictions is found for the precession period as a function of the orbit amplitude and the number of condensed atoms. In configurations with two or more vortices, we see signatures of vortex-vortex interaction in the shape and visibility of the orbits. In addition, when more than two vortices are present, their decay is faster than the thermal decay observed for one or two vortices. The possible role of vortex reconnection processes is discussed.

  19. {sup 85}Rb tunable-interaction Bose-Einstein condensate machine

    SciTech Connect

    Altin, P. A.; Robins, N. P.; Doering, D.; Debs, J. E.; Poldy, R.; Figl, C.; Close, J. D.

    2010-06-15

    We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of {sup 85}Rb with tunable interparticle interactions. We use sympathetic cooling with {sup 87}Rb in two stages, initially in a tight Ioffe-Pritchard magnetic trap and subsequently in a weak, large-volume, crossed optical dipole trap, using the 155 G Feshbach resonance to manipulate the elastic and inelastic scattering properties of the {sup 85}Rb atoms. Typical {sup 85}Rb condensates contain 4x10{sup 4} atoms with a scattering length of a=+200a{sub 0}. Many aspects of the design presented here could be adapted to other dual-species BEC machines, including those involving degenerate Fermi-Bose mixtures. Our minimalist apparatus is well suited to experiments on dual-species and spinor Rb condensates, and has several simplifications over the {sup 85}Rb BEC machine at JILA, which we discuss at the end of this article.

  20. Vortex formation in a fast rotating Bose-Einstein condensate

    SciTech Connect

    Ghosh, Tarun Kanti

    2004-04-01

    We study rotational motion of an interacting atomic Bose-Einstein condensate confined in a quadratic-plus-quartic potential. We calculate the lowest energy surface mode frequency and show that a symmetric trapped (harmonic and quartic) Bose-Einstein condensate breaks the rotational symmetry of the Hamiltonian when rotational frequency is greater than one-half of the lowest energy surface mode frequency. We argue that the formation of a vortex is not possible in a noninteracting as well as in an attractive Bose-Einstein condensate confined in a harmonic trap due to the absence of the spontaneous shape deformation, but it can occur which leads to the vortex formation if we add an additional quartic potential. Moreover, the spontaneous shape deformation and consequently the formation of a vortex in an attractive system depends on the strengths of the two-body interaction and the quartic potential.

  1. Competing interactions in population-imbalanced two-component Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Galteland, Peder Notto; Sudbø, Asle

    2016-08-01

    We consider a two-component Bose-Einstein condensate with and without synthetic "spin-orbit" interactions in two dimensions. Density and phase fluctuations of the condensate are included, allowing us to study the impact of thermal fluctuations and density-density interactions on the physics originating with spin-orbit interactions. In the absence of spin-orbit interactions, we find that intercomponent density interactions deplete the minority condensate. The thermally driven phase transition is driven by coupled density and phase-fluctuations, but is nevertheless shown to be a phase-transition in the Kosterlitz-Thouless universality class with close to universal amplitude ratios irrespective of whether both the minority- and majority condensates exist in the ground state, or only one condensate exists. In the presence of spin-orbit interactions we observe three separate phases, depending on the strength of the spin-orbit coupling and intercomponent density-density interactions: a phase-modulated phase with uniform amplitudes for small intercomponent interactions, a completely imbalanced, effectively single-component condensate for intermediate spin-orbit coupling strength and sufficiently large intercomponent interactions, and a phase-modulated and amplitude-modulated phase for sufficiently large values of both the spin-orbit coupling and the intercomponent density-density interactions. The phase that is modulated by a single q -vector only is observed to transition into an isotropic liquid through a strong depinning transition with periodic boundary conditions, which weakens with open boundaries.

  2. Variational methods with coupled Gaussian functions for Bose-Einstein condensates with long-range interactions. I. General concept

    SciTech Connect

    Rau, Stefan; Main, Joerg; Wunner, Guenter

    2010-08-15

    The variational method of coupled Gaussian functions is applied to Bose-Einstein condensates with long-range interactions. The time dependence of the condensate is described by dynamical equations for the variational parameters. We present the method and analytically derive the dynamical equations from the time-dependent Gross-Pitaevskii equation. The stability of the solutions is investigated using methods of nonlinear dynamics. The concept presented in this article will be applied to Bose-Einstein condensates with monopolar 1/r and dipolar 1/r{sup 3} interaction in the subsequent article [S. Rau et al., Phys. Rev. A 82, 023611 (2010)], where we will present a wealth of phenomena obtained using the ansatz with coupled Gaussian functions.

  3. Effects of interaction on thermodynamics of a repulsive Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, Satadal; Das, Tapan Kumar; Chakrabarti, Barnali

    2013-11-01

    We report the effects of interaction on thermodynamic properties of a repulsive Bose-Einstein condensate confined in a harmonic trap by using the correlated potential harmonics expansion method. This many-body technique permits the use of a realistic interactomic interaction, which gives rise to the effective long-range interaction of the condensate in terms of the s-wave scattering length. We have computed temperature (T) dependence of the chemical potential, specific heat, condensate fraction, entropy, pressure, and the average energy per particle of a system containing a large number (A) of 87Rb atoms in the Joint Institute for Laboratory Astrophysics (JILA) trap. The repulsion among the interacting bosons results in a small but measurable drop of condensate fraction and critical temperature (Tc), compared to those of a noninteracting condensate. These are in agreement with the experiment. Although all thermodynamic quantities have a strong dependence on A and to a smaller extent on the interatomic interaction, our numerical calculation appears to show that a thermodynamic quantity per particle follows a universal behavior as a function of T/Tc. This shows the importance of Tc for all thermodynamic properties of the condensate. As expected, for T>Tc, these properties follow those of a trapped noncondensed Bose gas.

  4. Matter wave switching in Bose-Einstein condensates via intensity redistribution soliton interactions

    SciTech Connect

    Rajendran, S.; Lakshmanan, M.; Muruganandam, P.

    2011-02-15

    Using time dependent nonlinear (s-wave scattering length) coupling between the components of a weakly interacting two component Bose-Einstein condensate (BEC), we show the possibility of matter wave switching (fraction of atoms transfer) between the components via shape changing/intensity redistribution (matter redistribution) soliton interactions. We investigate the exact bright-bright N-soliton solution of an effective one-dimensional (1D) two component BEC by suitably tailoring the trap potential, atomic scattering length, and atom gain or loss. In particular, we show that the effective 1D coupled Gross-Pitaevskii equations with time dependent parameters can be transformed into the well known completely integrable Manakov model described by coupled nonlinear Schroedinger equations by effecting a change of variables of the coordinates and the wave functions under certain conditions related to the time dependent parameters. We obtain the one-soliton solution and demonstrate the shape changing/matter redistribution interactions of two and three-soliton solutions for the time-independent expulsive harmonic trap potential, periodically modulated harmonic trap potential, and kinklike modulated harmonic trap potential. The standard elastic collision of solitons occur only for a specific choice of soliton parameters.

  5. Variational methods with coupled Gaussian functions for Bose-Einstein condensates with long-range interactions. II. Applications

    NASA Astrophysics Data System (ADS)

    Rau, Stefan; Main, Jörg; Cartarius, Holger; Köberle, Patrick; Wunner, Günter

    2010-08-01

    Bose-Einstein condensates with an attractive 1/r interaction and with dipole-dipole interaction are investigated in the framework of the Gaussian variational ansatz introduced by S. Rau, J. Main, and G. Wunner [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.82.023610 82, 023610 (2010)]. We demonstrate that the method of coupled Gaussian wave packets is a full-fledged alternative to direct numerical solutions of the Gross-Pitaevskii equation, or even superior in that coupled Gaussians are capable of producing both stable and unstable states of the Gross-Pitaevskii equation and thus of giving access to yet unexplored regions of the space of solutions of the Gross-Pitaevskii equation. As an alternative to numerical solutions of the Bogoliubov-de Gennes equations, the stability of the stationary condensate wave functions is investigated by analyzing the stability properties of the dynamical equations of motion for the Gaussian variational parameters in the local vicinity of the stationary fixed points. For blood-cell-shaped dipolar condensates it is shown that on the route to collapse the condensate passes through a pitchfork bifurcation, where the ground state itself turns unstable, before it finally vanishes in a tangent bifurcation.

  6. Variational methods with coupled Gaussian functions for Bose-Einstein condensates with long-range interactions. II. Applications

    SciTech Connect

    Rau, Stefan; Main, Joerg; Cartarius, Holger; Koeberle, Patrick; Wunner, Guenter

    2010-08-15

    Bose-Einstein condensates with an attractive 1/r interaction and with dipole-dipole interaction are investigated in the framework of the Gaussian variational ansatz introduced by S. Rau, J. Main, and G. Wunner [Phys. Rev. A 82, 023610 (2010)]. We demonstrate that the method of coupled Gaussian wave packets is a full-fledged alternative to direct numerical solutions of the Gross-Pitaevskii equation, or even superior in that coupled Gaussians are capable of producing both stable and unstable states of the Gross-Pitaevskii equation and thus of giving access to yet unexplored regions of the space of solutions of the Gross-Pitaevskii equation. As an alternative to numerical solutions of the Bogoliubov-de Gennes equations, the stability of the stationary condensate wave functions is investigated by analyzing the stability properties of the dynamical equations of motion for the Gaussian variational parameters in the local vicinity of the stationary fixed points. For blood-cell-shaped dipolar condensates it is shown that on the route to collapse the condensate passes through a pitchfork bifurcation, where the ground state itself turns unstable, before it finally vanishes in a tangent bifurcation.

  7. Reservoir interactions of a vortex in a trapped three-dimensional Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Rooney, S. J.; Allen, A. J.; Zülicke, U.; Proukakis, N. P.; Bradley, A. S.

    2016-06-01

    We simulate the dissipative evolution of a vortex in a trapped finite-temperature dilute-gas Bose-Einstein condensate using first-principles open-systems theory. Simulations of the complete stochastic projected Gross-Pitaevskii equation for a partially condensed Bose gas containing a single quantum vortex show that the transfer of condensate energy to the incoherent thermal component without population transfer provides an important channel for vortex decay. For the lower temperatures considered, this effect is significantly larger that the population transfer process underpinning the standard theory of vortex decay, and is the dominant determinant of the vortex lifetime. A comparison with the Zaremba-Nikuni-Griffin kinetic (two-fluid) theory further elucidates the role of the particle transfer interaction, and suggests the need for experimental testing of reservoir interaction theory. The dominance of this particular energetic decay mechanism for this open quantum system should be testable with current experimental setups, and its observation would have broad implications for the dynamics of atomic matter waves and experimental studies of dissipative phenomena.

  8. Interacting spin-orbit-coupled spin-1 Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Sun, Kuei; Qu, Chunlei; Xu, Yong; Zhang, Yongping; Zhang, Chuanwei

    2016-02-01

    The recent experimental realization of spin-orbit (SO) coupling for spin-1 ultracold atoms opens an interesting avenue for exploring SO-coupling-related physics in large-spin systems, which is generally unattainable in electronic materials. In this paper, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 Bose-Einstein condensates (BECs) in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting in-phase or out-of-phase modulating patterns between spin-tensor and zero-spin-component density waves. We characterize the phase transitions between different phases using the spin-tensor density as well as the collective dipole motion of the BEC. We show that there exists a double maxon-roton structure in the Bogoliubov-excitation spectrum, attributed to the three band minima of the SO-coupled spin-1 BEC.

  9. Dynamics of analytical three-dimensional matter-wave solutions in Bose-Einstein condensates with multi-body interactions

    NASA Astrophysics Data System (ADS)

    Jin, Hai-Qin; Dai, Wei; Tong, Aihong; Cai, Ze-Bin; Liang, Jian-Chu; He, Jun-Rong

    2014-03-01

    Using the F-expansion method we obtain a class of analytical matter-wave solutions to Bose-Einstein condensates with multi-body interactions through the three-dimensional quintic Gross-Pitaevskii equation. Our results demonstrate that the dynamics of matter-wave solutions can be controlled by selecting the potential, quintic nonlinearity, and gain coefficients. The obtained matter-wave solutions may be generated by tuning the cubic nonlinearity to zero via the Feschbach resonance technique and making the quintic nonlinearity increasing rapidly enough toward the periphery. The stability analysis of the obtained matter-wave solutions is investigated analytically and numerically.

  10. Interactions of Low-Energy Ions and Electrons with Bose-Einstein Condensates

    DTIC Science & Technology

    2011-09-13

    The work was published in “Bose-Einstein condensate inside a Bragg-reflecting atom cavity,” R. Zhang, R. E. Sapiro, N. V. Morrow, R. R. Mhaskar ...lattice and harmonic trap”, R. Zhang, R. E. Sapiro, R. R. Mhaskar , G. Raithel, Phys. Rev. A 78, 053607 – 1 - 7 (Nov. 2008). 3) We have applied a...provided support for several graduate students, two of which have graduated (Rahul Mhaskar , Rui Zhang) and one (David Anderson) who has advanced to

  11. Stability of the quantized circulation of an attractive Bose-Einstein condensate in a rotating torus

    SciTech Connect

    Kanamoto, Rina; Saito, Hiroki; Ueda, Masahito

    2003-10-01

    We investigate rotational properties of a system of attractive bosons confined in a one-dimensional torus. Two kinds of ground states, uniform-density and bright soliton, are obtained analytically as functions of the strength of interaction and of the rotational frequency of the torus. The quantization of circulation appears in the uniform-density state, but disappears upon formation of the soliton. By comparing the results of exact diagonalization with those predicted by the Bogoliubov theory, we show that the Bogoliubov theory is valid at absolute zero over a wide range of parameters. At finite temperatures we employ the exact diagonalization method to examine how thermal fluctuations smear the plateaus of the quantized circulation. Finally, by rotating the system with an axisymmetry-breaking potential, we clarify the process by which the quantized circulation becomes thermodynamically stabilized.

  12. Creation of two-dimensional composite solitons in spin-orbit-coupled self-attractive Bose-Einstein condensates in free space

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Hidetsugu; Li, Ben; Malomed, Boris A.

    2014-03-01

    It is commonly known that two-dimensional mean-field models of optical and matter waves with cubic self-attraction cannot produce stable solitons in free space because of the occurrence of collapse in the same setting. By means of numerical analysis and variational approximation, we demonstrate that the two-component model of the Bose-Einstein condensate with the spin-orbit Rashba coupling and cubic attractive interactions gives rise to solitary-vortex complexes of two types: semivortices (SVs, with a vortex in one component and a fundamental soliton in the other), and mixed modes (MMs, with topological charges 0 and ±1 mixed in both components). These two-dimensional composite modes can be created using the trapping harmonic-oscillator (HO) potential, but remain stable in free space, if the trap is gradually removed. The SVs and MMs realize the ground state of the system, provided that the self-attraction in the two components is, respectively, stronger or weaker than the cross attraction between them. The SVs and MMs which are not the ground states are subject to a drift instability. In free space (in the absence of the HO trap), modes of both types degenerate into unstable Townes solitons when their norms attain the respective critical values, while there is no lower existence threshold for the stable modes. Moving free-space stable solitons are also found in the present non-Galilean-invariant system, up to a critical velocity. Collisions between two moving solitons lead to their merger into a single one.

  13. Creation of two-dimensional composite solitons in spin-orbit-coupled self-attractive Bose-Einstein condensates in free space.

    PubMed

    Sakaguchi, Hidetsugu; Li, Ben; Malomed, Boris A

    2014-03-01

    It is commonly known that two-dimensional mean-field models of optical and matter waves with cubic self-attraction cannot produce stable solitons in free space because of the occurrence of collapse in the same setting. By means of numerical analysis and variational approximation, we demonstrate that the two-component model of the Bose-Einstein condensate with the spin-orbit Rashba coupling and cubic attractive interactions gives rise to solitary-vortex complexes of two types: semivortices (SVs, with a vortex in one component and a fundamental soliton in the other), and mixed modes (MMs, with topological charges 0 and ±1 mixed in both components). These two-dimensional composite modes can be created using the trapping harmonic-oscillator (HO) potential, but remain stable in free space, if the trap is gradually removed. The SVs and MMs realize the ground state of the system, provided that the self-attraction in the two components is, respectively, stronger or weaker than the cross attraction between them. The SVs and MMs which are not the ground states are subject to a drift instability. In free space (in the absence of the HO trap), modes of both types degenerate into unstable Townes solitons when their norms attain the respective critical values, while there is no lower existence threshold for the stable modes. Moving free-space stable solitons are also found in the present non-Galilean-invariant system, up to a critical velocity. Collisions between two moving solitons lead to their merger into a single one.

  14. Weakly interacting Bose-Einstein condensates in temperature-dependent generic traps

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Briscese, F.; Grether, M.; de Llano, M.

    2015-04-01

    We study the shift Δ T c in the condensation temperature of an atomic Bose-Einstein condensate trapped in a temperature-dependent three-dimensional generic potential. With no assumptions other than the mean-field approach and the semiclassical approximation, it is shown that the inclusion of a T-dependent trap improves upon the pure semiclassical result giving better agreement between the predicted Δ T c value and its experimental value. However, despite this improvement, the effect of a T-dependent trap is not sufficient to fully reduce the discrepancy between theoretical prediction and data.

  15. Covariant theory of Bose-Einstein condensates in curved spacetimes with electromagnetic interactions: The hydrodynamic approach

    NASA Astrophysics Data System (ADS)

    Chavanis, Pierre-Henri; Matos, Tonatiuh

    2017-01-01

    We develop a hydrodynamic representation of the Klein-Gordon-Maxwell-Einstein equations. These equations combine quantum mechanics, electromagnetism, and general relativity. We consider the case of an arbitrary curved spacetime, the case of weak gravitational fields in a static or expanding background, and the nonrelativistic (Newtonian) limit. The Klein-Gordon-Maxwell-Einstein equations govern the evolution of a complex scalar field, possibly describing self-gravitating Bose-Einstein condensates, coupled to an electromagnetic field. They may find applications in the context of dark matter, boson stars, and neutron stars with a superfluid core.

  16. Polymer Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Chacón-Acosta, G.

    2013-05-01

    In this work we analyze a non-interacting one-dimensional polymer Bose-Einstein condensate in a harmonic trap within the semiclassical approximation. We use an effective Hamiltonian coming from the polymer quantization that arises in loop quantum gravity. We calculate the number of particles in order to obtain the critical temperature. The Bose-Einstein functions are replaced by series, whose high order terms are related to powers of the polymer length. It is shown that the condensation temperature presents a shift respect to the standard case, for small values of the polymer scale. In typical experimental conditions, it is possible to establish a bound for λ2 up to ≲10-16 m2. To improve this bound we should decrease the frequency of the trap and also decrease the number of particles.

  17. Solvable model of a generic trapped mixture of interacting bosons: reduced density matrices and proof of Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Alon, Ofir E.

    2017-07-01

    A mixture of two kinds of identical bosons, species 1 with N 1 bosons of mass m 1 and species 2 with N 2 bosons of mass m 2, held in a harmonic potential of frequency ω and interacting by harmonic intra-species and inter-species particle-particle interactions of strengths λ1 , λ2 , and λ12 is discussed. This is an exactly-solvable model of a generic mixture of trapped interacting bosons which allows one to investigate and determine analytically properties of interest. To start, closed form expressions for the frequencies, ground-state energy, and wave-function of the mixture are obtained and briefly analyzed as a function of the masses, numbers of particles, and strengths and signs of interactions. To prove Bose-Einstein condensation of the mixture three steps are needed. First, we integrate the all-particle density matrix, employing a four-parameter matrix-recurrence relations, down to the lowest-order intra-species and inter-species reduced density matrices of the mixture. Second, the coupled Gross-Pitaevskii (mean-field) equations of the mixture are solved analytically. Third, we analyze the mixture’s reduced density matrices in the limit of an infinite number of particles of both species 1 and 2 (when the interaction parameters, i.e. the products of the number of particles times the intra-species and inter-species interaction strengths, are held fixed) and prove that: (i) both species 1 and 2 are 100% condensed; (ii) the inter-species reduced density matrix per particle is separable and given by the product of the intra-species reduced density matrices per particle; and (iii) the mixture’s energy per particle, and reduced density matrices and densities per particle all coincide with the Gross-Pitaevskii quantities. Finally, when the infinite-particle limit is taken with respect to, say, species 1 only (with interaction parameters held fixed) we prove that: (iv) only species 1 is 100% condensed and its reduced density matrix and density per particle, as

  18. Scattering of an attractive Bose-Einstein condensate from a barrier: Formation of quantum superposition states

    NASA Astrophysics Data System (ADS)

    Streltsov, Alexej I.; Alon, Ofir E.; Cederbaum, Lorenz S.

    2009-10-01

    Scattering in one dimension of an attractive ultracold bosonic cloud from a barrier can lead to the formation of two nonoverlapping clouds. Once formed, the clouds travel with constant velocity, in general different in magnitude from that of the incoming cloud, and do not disperse. The phenomenon and its mechanism—transformation of kinetic energy to internal energy of the scattered cloud—are obtained by solving the time-dependent many-boson Schrödinger equation. The analysis of the wave function shows that the object formed corresponds to a quantum superposition state of two distinct wave packets traveling through real space.

  19. Interaction assisted tunneling of a Bose-Einstein condensate out of a quasi bound state

    NASA Astrophysics Data System (ADS)

    Potnis, Shreyas; Ramos, Ramon; Maeda, Kenji; Carr, Lincoln D.; Steinberg, Aephraim

    2015-05-01

    We experimentally measure the tunneling rate of a 87Rb Bose-Einstein condensate prepared in a quasi-bound state. Using the combination of a magnetic quadrupole trap and a thin 1.1 μm barrier created using a blue-detuned sheet of light, we can create traps with controllable depth and lifetime. The thin tunnel barrier allows for a tunable tunneling rate from 30 s-1 to 1 s-1 . The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes-- classical over the barrier spilling, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate goes down exponentially with decreasing chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation and WKB calculations.

  20. Chaotic behavior of three interacting vortices in a confined Bose-Einstein condensate

    SciTech Connect

    Kyriakopoulos, Nikos; Koukouloyannis, Vassilis; Skokos, Charalampos; Kevrekidis, Panayotis G.

    2014-06-01

    Motivated by recent experimental works, we investigate a system of vortex dynamics in an atomic Bose-Einstein condensate (BEC), consisting of three vortices, two of which have the same charge. These vortices are modeled as a system of point particles which possesses a Hamiltonian structure. This tripole system constitutes a prototypical model of vortices in BECs exhibiting chaos. By using the angular momentum integral of motion, we reduce the study of the system to the investigation of a two degree of freedom Hamiltonian model and acquire quantitative results about its chaotic behavior. Our investigation tool is the construction of scan maps by using the Smaller ALignment Index as a chaos indicator. Applying this approach to a large number of initial conditions, we manage to accurately and efficiently measure the extent of chaos in the model and its dependence on physically important parameters like the energy and the angular momentum of the system.

  1. Dynamics of kink-dark solitons in Bose-Einstein condensates with both two- and three-body interactions.

    PubMed

    Mohamadou, Alidou; Wamba, Etienne; Lissouck, Daniel; Kofane, Timoleon C

    2012-04-01

    The matter-wave solutions of Bose-Einstein condensates with three-body interaction are examined through the one-dimensional Gross-Pitaevskii equation. By using a modified lens-type transformation and a further extension of the tanh-function method we obtain the exact analytical solutions which describe the propagation of kink-shaped solitons, anti-kink-shaped solitons, and other families of solitary waves. We realize that the shape of a kink solitary wave depends on both the scattering length and the parameter of atomic exchange with the substrate. The stability of the solitary waves is examined using analytical and numerical methods. Our results can also be applied to nonlinear optics in the presence of cubic-quintic media.

  2. Theory of coherence in Bose-Einstein condensation phenomena in a microwave-driven interacting magnon gas

    SciTech Connect

    Rezende, Sergio M.

    2009-05-01

    Strong experimental evidences of the formation of quasiequilibrium Bose-Einstein condensation (BEC) of magnons at room temperature in a film of yttrium iron garnet (YIG) excited by microwave radiation have been recently reported. Here we present a theory for the dynamics of the magnon gas driven by a microwave field far out of equilibrium that provides rigorous support for the formation of a BEC of magnons in a YIG film magnetized in the plane. We show that if the microwave driving power exceeds a threshold value the nonlinear magnetic interactions create cooperative mechanisms for the onset of a phase transition leading to the spontaneous generation of quantum coherence and magnetic dynamic order in a macroscopic scale. The theoretical results agree with the experimental data for the intensity and the decay rate of the Brillouin light scattering from the BEC as a function of power and for the microwave emission from the uniform mode generated by the confluence of BEC magnon pairs.

  3. Verification of exceptional points in the collapse dynamics of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Brinker, Jonas; Fuchs, Jacob; Main, Jörg; Wunner, Günter; Cartarius, Holger

    2015-01-01

    In Bose-Einstein condensates with an attractive contact interaction the stable ground state and an unstable excited state emerge in a tangent bifurcation at a critical value of the scattering length. At the bifurcation point both the energies and the wave functions of the two states coalesce, which is the characteristic of an exceptional point. In numerical simulations signatures of the exceptional point can be observed by encircling the bifurcation point in the complex extended space of the scattering length, however, this method cannot be applied in an experiment. Here we show in which way the exceptional point effects the collapse dynamics of the Bose-Einstein condensate. The harmonic inversion analysis of the time signal given as the spatial extension of the collapsing condensate wave function can provide clear evidence for the existence of an exceptional point. This method can be used for an experimental verification of exceptional points in Bose-Einstein condensates.

  4. Soliton resonance in bose-einstein condensate

    NASA Technical Reports Server (NTRS)

    Zak, Michail; Kulikov, I.

    2002-01-01

    A new phenomenon in nonlinear dispersive systems, including a Bose-Einstein Condensate (BEC), has been described. It is based upon a resonance between an externally induced soliton and 'eigen-solitons' of the homogeneous cubic Schrodinger equation. There have been shown that a moving source of positive /negative potential induces bright /dark solitons in an attractive / repulsive Bose condensate.

  5. Soliton resonance in bose-einstein condensate

    NASA Technical Reports Server (NTRS)

    Zak, Michail; Kulikov, I.

    2002-01-01

    A new phenomenon in nonlinear dispersive systems, including a Bose-Einstein Condensate (BEC), has been described. It is based upon a resonance between an externally induced soliton and 'eigen-solitons' of the homogeneous cubic Schrodinger equation. There have been shown that a moving source of positive /negative potential induces bright /dark solitons in an attractive / repulsive Bose condensate.

  6. Dynamics of trapped interacting vortices in Bose-Einstein condensates: a role of breathing degree of freedom

    NASA Astrophysics Data System (ADS)

    Nakamura, Katsuhiro; Babajanov, Doniyor; Matrasulov, Davron; Kobayashi, Michikazu; Muruganandam, Paulsamy

    2016-08-01

    With use of a variational principle, we investigate a role of breathing width degree of freedom in the effective theory of interacting vortices in a trapped single-component Bose-Einstein condensates in two dimensions, under strong repulsive cubic nonlinearity. For the trial function, we choose a product of two vortex functions, assuming a pair interaction, and employ the amplitude form of each vortex function in the Padé approximation, which accommodates a hallmark of the vortex core. We obtain the Lagrange equation for the interacting vortex-core coordinates coupled with the time-derivative of width and also its Hamilton formalism by having recourse to a non-standard Poisson bracket. By solving the Hamilton equation, we find rapid radial breathing oscillations superposed on the slower rotational motion of vortex cores, consistent with numerical solutions of the Gross-Pitaevskii equation. In higher-energy states of two vortex systems, the breathing width degree of freedom plays the role of a kicking in the kicked rotator, and generates chaos with a structure of sea-urchin needles. The by-products of the present variational approach include: (1) the charge-dependent logarithmic inter-vortex interaction multiplied with a pre-factor, which depends on the scalar product of a pair of core-position vectors; (2) the charge-independent short-range repulsive inter-vortex interaction and spring force.

  7. Dynamical stabilization of two-dimensional trapless Bose-Einstein condensates by three-body interaction and quantum fluctuations

    NASA Astrophysics Data System (ADS)

    Sabari, S.; Porsezian, K.; Muruganandam, P.

    2017-10-01

    Analyzing a Gross-Pitaevskii equation with cubic, quartic, and quintic nonlinearities through analytical and numerical methods, we examine the stability of two-dimensional (2D) trapless Bose-Einstein condensates (BECs) with two-, three-body interactions and quantum fluctuations. Applying a variational approach, we derive the equation of motion and effective potential to discuss in detail the stability of the BECs in 2D free space. We show that with the aid of quantum fluctuations it is possible to stabilize 2D trapless BEC without any oscillatory nonlinearities. Also, there is an enhancement of the stability of the system, due to the inclusion of the three-body interaction and quantum fluctuations in addition to the two-body interaction. We further study the stability of 2D trapless BECs with rapid periodic temporal modulation of scattering length by using a Feshbach resonance. We discuss all possible ways of stabilization of trapless BECs in 2D by three-body interaction and quantum fluctuations. Finally, we verify our analytical results with numerical simulation using split-step Crank-Nicholson method. These match well with the analytical predictions.

  8. Bose-Einstein Condensation

    SciTech Connect

    El-Sherbini, Th.M.

    2005-03-17

    This article gives a brief review of Bose-Einstein condensation. It is an exotic quantum phenomenon that was observed in dilute atomic gases for the first time in 1995. It exhibits a new state of matter in which a group of atoms behaves as a single particle. Experiments on this form of matter are relevant to many different areas of physics- from atomic clocks and quantum computing to super fluidity, superconductivity and quantum phase transition.

  9. Bose-Einstein condensate strings

    NASA Astrophysics Data System (ADS)

    Harko, Tiberiu; Lake, Matthew J.

    2015-02-01

    We consider the possible existence of gravitationally bound general relativistic strings consisting of Bose-Einstein condensate (BEC) matter which is described, in the Newtonian limit, by the zero temperature time-dependent nonlinear Schrödinger equation (the Gross-Pitaevskii equation), with repulsive interparticle interactions. In the Madelung representation of the wave function, the quantum dynamics of the condensate can be formulated in terms of the classical continuity equation and the hydrodynamic Euler equations. In the case of a condensate with quartic nonlinearity, the condensates can be described as a gas with two pressure terms, the interaction pressure, which is proportional to the square of the matter density, and the quantum pressure, which is without any classical analogue, though, when the number of particles in the system is high enough, the latter may be neglected. Assuming cylindrical symmetry, we analyze the physical properties of the BEC strings in both the interaction pressure and quantum pressure dominated limits, by numerically integrating the gravitational field equations. In this way we obtain a large class of stable stringlike astrophysical objects, whose basic parameters (mass density and radius) depend sensitively on the mass and scattering length of the condensate particle, as well as on the quantum pressure of the Bose-Einstein gas.

  10. Stripe phase and double-roton excitations in interacting spin-orbit-coupled spin-1 Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Sun, Kuei; Qu, Chunlei; Xu, Yong; Zhang, Yongping; Zhang, Chuanwei

    Spin-orbit (SO) coupling plays a major role in many important phenomena in condensed matter physics. However, the SO coupling physics in high-spin systems, especially with superfluids, has not been well explored because of the spin half of electrons in solids. In this context, the recent experimental realization of spin-orbit coupling in spin-1 Bose-Einstein condensates (BECs) has opened a completely new avenue for exploring SO-coupled high-spin superfluids. Nevertheless, the experiment has only revealed the single-particle physics of the system. Here, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 BECs in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting two modulating patterns. We characterize the phase transitions between different phases using the spin-tensor density as well as the collective dipole motion of the BEC. We show that there exists a new type of double maxon-roton structure in the Bogoliubov-excitation spectrum, attributing to the three band minima of the SO-coupled spin-1 BEC. Our work could motivate further theoretical and experimental study along this direction.

  11. Bright solitons in a quasi-one-dimensional reduced model of a dipolar Bose-Einstein condensate with repulsive short-range interactions

    NASA Astrophysics Data System (ADS)

    Chiquillo, Emerson

    2014-08-01

    We study the formation and dynamics of bright solitons in a quasi-one-dimensional reduced mean-field Gross-Pitaevskii equation of a dipolar Bose-Einstein condensate with repulsive short-range interactions. The study is carried out using a variational approximation and a numerical solution. Plots of chemical potential and root mean square (rms) size of solitons are obtained for the quasi-one-dimensional model of three different dipolar condensates of 52Cr, 168Er and 164Dy atoms. The results achieved are in good agreement with those produced by the full three-dimensional mean-field model of the condensate. We also study the dynamics of the collision of a train of two solitons in the quasi-one-dimensional model of every condensate above. At small velocities (zero or close to zero) the dynamics is attractive for a phase difference δ = 0, the solitons coalesce and these oscillate, forming a bound soliton molecule. For a phase difference δ = π the effect is repulsive. At large velocities the collision is independent of the initial phase difference δ. This is quasi-elastic and the result is two quasi-solitons.

  12. Accurate control of a Bose-Einstein condensate by managing the atomic interaction

    SciTech Connect

    Morales-Molina, L.; Arevalo, E.

    2010-07-15

    We exploit the variation of the atomic interaction in order to move ultracold atoms with attractive interaction across an ac-driven periodic lattice. By breaking relevant symmetries, a gathering of atoms is achieved. Accurate control of the gathered atoms' positions can be demonstrated via the control of the atomic localization process. The localization process is analyzed with the help of the nonlinear Floquet states where the Landau-Zener tunneling between states is observed and controlled. Transport effects in the presence of disorder are discussed.

  13. Competition between Bose-Einstein Condensation and Spin Dynamics.

    PubMed

    Naylor, B; Brewczyk, M; Gajda, M; Gorceix, O; Maréchal, E; Vernac, L; Laburthe-Tolra, B

    2016-10-28

    We study the impact of spin-exchange collisions on the dynamics of Bose-Einstein condensation by rapidly cooling a chromium multicomponent Bose gas. Despite relatively strong spin-dependent interactions, the critical temperature for Bose-Einstein condensation is reached before the spin degrees of freedom fully thermalize. The increase in density due to Bose-Einstein condensation then triggers spin dynamics, hampering the formation of condensates in spin-excited states. Small metastable spinor condensates are, nevertheless, produced, and they manifest in strong spin fluctuations.

  14. Twisted spin vortices in a spin-1 Bose-Einstein condensate with Rashba spin-orbit coupling and dipole-dipole interaction

    NASA Astrophysics Data System (ADS)

    Kato, Masaya; Zhang, Xiao-Fei; Sasaki, Daichi; Saito, Hiroki

    2016-10-01

    We consider a spin-1 Bose-Einstein condensate with Rashba spin-orbit coupling and dipole-dipole interaction confined in a cigar-shaped trap. Due to the combined effects of spin-orbit coupling, dipole-dipole interaction, and trap geometry, the system exhibits a rich variety of ground-state spin structures, including twisted spin vortices. The ground-state phase diagram is determined with respect to the strengths of the spin-orbit coupling and dipole-dipole interaction.

  15. Discrete breather and soliton-mode collective excitations in Bose-Einstein condensates in a deep optical lattice with tunable three-body interactions

    NASA Astrophysics Data System (ADS)

    Alakhaly, Galal Ahmed; Dey, Bishwajyoti

    2015-05-01

    We have studied the dynamic evolution of the collective excitations in Bose-Einstein condensates in a deep optical lattice with tunable three-body interactions. Their dynamics is governed by a high order discrete nonlinear Schrödinger equation (DNLSE). The dynamical phase diagram of the system is obtained using the variational method. The dynamical evolution shows very interesting features. The discrete breather phase totally disappears in the regime where the three-body interaction completely dominates over the two-body interaction. The soliton phase in this particular regime exists only when the soliton line approaches the critical line in the phase diagram. When weak two-body interactions are reintroduced into this regime, the discrete breather solutions reappear, but occupies a very small domain in the phase space. Likewise, in this regime, the soliton as well as the discrete breather phases completely disappear if the signs of the two-and three-body interactions are opposite. We have analysed the causes of this unusual dynamical evolution of the collective excitations of the Bose-Einstein condensate with tunable interactions. We have also performed direct numerical simulations of the governing DNLS equation to show the existence of the discrete soliton solution as predicted by the variational calculations, and also to check the long term stability of the soliton solution.

  16. Bose-Einstein condensates in rotating lattices.

    PubMed

    Bhat, Rajiv; Holland, M J; Carr, L D

    2006-02-17

    Strongly interacting bosons in a two-dimensional rotating square lattice are investigated via a modified Bose-Hubbard Hamiltonian. Such a system corresponds to a rotating lattice potential imprinted on a trapped Bose-Einstein condensate. Second-order quantum phase transitions between states of different symmetries are observed at discrete rotation rates. For the square lattice we study, there are four possible ground-state symmetries.

  17. Short-range intervortex interaction and interacting dynamics of half-quantized vortices in two-component Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Kasamatsu, Kenichi; Eto, Minoru; Nitta, Muneto

    2016-01-01

    We study the interaction and dynamics of two half-quantized vortices in two-component Bose-Einstein condensates. Using the Padé approximation for the vortex core profile, we calculate the intervortex potential, whose asymptotic form for a large distance has been derived by Eto et al. [Phys. Rev. A 83, 063603 (2011), 10.1103/PhysRevA.83.063603]. Through numerical simulations of the two-dimensional Gross-Pitaevskii equations, we reveal different kinds of dynamical trajectories of the vortices depending on the combinations of signs of circulations and the intercomponent density coupling. Under the adiabatic limit, we derive the equations of motion for the vortex coordinates, in which the motion is caused by the balance between Magnus force and the intervortex forces. The initial velocity of the vortex motion can be explained quantitatively by this point vortex approximation, but understanding the long-time behavior of the dynamics needs more consideration beyond our model.

  18. Impurity in a Bose-Einstein condensate: Study of the attractive and repulsive branch using quantum Monte Carlo methods

    NASA Astrophysics Data System (ADS)

    Ardila, L. A. Peña; Giorgini, S.

    2015-09-01

    We investigate the properties of an impurity immersed in a dilute Bose gas at zero temperature using quantum Monte Carlo methods. The interactions between bosons are modeled by a hard-sphere potential with scattering length a , whereas the interactions between the impurity and the bosons are modeled by a short-range, square-well potential where both the sign and the strength of the scattering length b can be varied by adjusting the well depth. We characterize the attractive and the repulsive polaron branch by calculating the binding energy and the effective mass of the impurity. Furthermore, we investigate the structural properties of the bath, such as the impurity-boson contact parameter and the change of the density profile around the impurity. At the unitary limit of the impurity-boson interaction, we find that the effective mass of the impurity remains smaller than twice its bare mass, while the binding energy scales with ℏ2n2 /3/m , where n is the density of the bath and m is the common mass of the impurity and the bosons in the bath. The implications for the phase diagram of binary Bose-Bose mixtures at low concentrations are also discussed.

  19. Mach-Zehnder interferometry with interacting trapped Bose-Einstein condensates

    SciTech Connect

    Grond, Julian; Hohenester, Ulrich; Schmiedmayer, Joerg; Smerzi, Augusto

    2011-08-15

    We theoretically analyze a Mach-Zehnder interferometer with trapped condensates and find that it is surprisingly stable against the nonlinearity induced by interparticle interactions. The phase sensitivity, which we study for number-squeezed input states, can overcome the shot noise limit and be increased up to the Heisenberg limit provided that a Bayesian or maximum-likelihood phase estimation strategy is used. We finally demonstrate the robustness of the Mach-Zehnder interferometer in the presence of interactions against condensate oscillations and a realistic atom-counting error.

  20. Creation of Long-Term Coherent Optical Memory via Controlled Nonlinear Interactions in Bose-Einstein Condensates

    SciTech Connect

    Zhang Rui; Garner, Sean R.; Hau, Lene Vestergaard

    2009-12-04

    A Bose-Einstein condensate confined in an optical dipole trap is used to generate long-term coherent memory for light, and storage times of more than 1 s are observed. Phase coherence of the condensate as well as controlled manipulations of elastic and inelastic atomic scattering processes are utilized to increase the storage fidelity by several orders of magnitude over previous schemes. The results have important applications for creation of long-distance quantum networks and for generation of entangled states of light and matter.

  1. Blow-up profile of Bose-Einstein condensate with singular potentials

    NASA Astrophysics Data System (ADS)

    Phan, Thanh Viet

    2017-07-01

    The paper is concerned with the Bose-Einstein condensate described by the attractive Gross-Pitaevskii equation in R2, where the external potential is unbounded from below. We show that when the interaction strength increases to a critical value, the Gross-Pitaevskii minimizer collapses to one singular point and we analyze the details of the collapse exactly up to the leading order.

  2. Bose-Einstein Condensation in a One-Dimensional System of Interacting Bosons

    NASA Astrophysics Data System (ADS)

    Tomchenko, Maksim

    2016-03-01

    Using the Vakarchuk formulae for the density matrix, we calculate the number Nk of atoms with momentum hbar k for the ground state of a uniform one-dimensional periodic system of interacting bosons. We obtain for impenetrable point bosons N0 ≈ 2√{N} and N_{k=2π j/L} ˜eq 0.31 N0/√{|j|}. That is, there is no condensate or quasicondensate on low levels at large N. For almost point bosons with weak coupling (β =ν 0m/π ^{2hbar 2n} ≪ 1), we obtain N0/N ≈ ( 2/N√{β }) ^{&sqrt{β; }/2} and N_{k=2π j/L} ≈ N0√{β }/4|j|^{1-√{β /2}}. In this case, the quasicondensate exists on the level with k=0 and on low levels with kne 0, if N is large and β is small (e.g., for N ˜ 10^{10} , β ˜ 0.01). A method of measurement of such fragmented quasicondensate is proposed.

  3. Dynamical instability of a Bose-Einstein condensate with higher-order interactions in an optical potential through a variational approach.

    PubMed

    Wamba, E; Sabari, S; Porsezian, K; Mohamadou, A; Kofané, T C

    2014-05-01

    We investigate the dynamical instability of Bose-Einstein condensates (BECs) with higher-order interactions immersed in an optical lattice with weak driving harmonic potential. For this, we compute both analytically and numerically a modified Gross-Pitaevskii equation with higher-order nonlinearity and external potentials generated by magnetic and optical fields. Using the time-dependent variational approach, we derive the ordinary differential equations for the time evolution of the amplitude and phase of modulational perturbation. Through an effective potential, we obtain the modulational instability condition of BECs and discuss the effect of the higher-order interaction in the dynamics of the condensates in presence of optical potential. We perform direct numerical simulations to support our analytical results, and good agreement is found.

  4. Nonlinear atom-photon-interaction-induced population inversion and inverted quantum phase transition of Bose-Einstein condensate in an optical cavity

    NASA Astrophysics Data System (ADS)

    Zhao, Xiuqin; Liu, Ni; Liang, J.-Q.

    2014-08-01

    In this paper we explore the rich structure of macroscopic many-particle quantum states for a Bose-Einstein condensate in an optical cavity with a tunable nonlinear atom-photon interaction [K. Baumann et al., Nature (London) 464, 1301 (2010), 10.1038/nature09009]. Population inversion, bistable normal phases, and the coexistence of normal-superradiant phases are revealed by adjusting the experimentally realizable interaction strength and pump-laser frequency. For the negative (effective) cavity frequency we observe, remarkably, an inverted quantum phase transition (QPT) from the superradiant to the normal phases with an increase in atom-field coupling, which is just opposite the QPT in the normal Dicke model. Bistable macroscopic states are derived analytically in terms of the spin-coherent-state variational method by taking into account both normal and inverted pseudospin states.

  5. Effects of three-body interactions on the instabilities and self-oscillations of the four-wave mixing in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ngounga Makoundit, G. J.; Ekogo, T. B.; Moubissi, A. B.; Ben-Bolie, G. H.; Kofane, T. C.

    2017-08-01

    In this paper, we analyze and discuss instabilities and self-oscillations of four-wave mixing in two-component Bose-Einstein condensates with two- and three-body interatomic interactions. The model is very accurately described in the mean-field approximation by the cubic-quintic Gross-Pitaevskii equation. The relation between the input and output field intensities is multivalued and the effects of the quintic nonlinearity on the self-oscillations of the system are studied. We have also found that the magnitude of the signal beam increases with the increase of the intensity of the probe beam, up to a saturated value, then it decreases with the increase of the intensity of the probe beam. We have shown that the three-body interatomic interactions enhance this saturated value.

  6. Towards a generalized Landau-Zener formula for an interacting Bose-Einstein condensate in a two-level system

    SciTech Connect

    Witthaut, D.; Graefe, E. M.; Korsch, H. J.

    2006-06-15

    We consider the Landau-Zener problem for a Bose-Einstein condensate in a linearly varying two-level system, for the full many-particle system as well as in the mean-field approximation. Novel nonlinear eigenstates emerge in the mean-field description, which leads to a breakdown of adiabaticity: The Landau-Zener transition probability does not vanish even in the adiabatic limit. It is shown that the emergence of nonlinear eigenstates and thus the breakdown of adiabaticity corresponds to quasi-degenerate avoided crossings of the many-particle levels. The many-particle problem can be solved approximately within an independent crossings approximation, which yields an explicit generalized Landau-Zener formula. A comparison to numerical results for the many-particle system and the mean-field approximation shows an excellent agreement.

  7. Dimensional reduction in Bose-Einstein condensed clouds of atoms confined in tight potentials of any geometry and any interaction strength

    NASA Astrophysics Data System (ADS)

    Sandin, P.; Ögren, M.; Gulliksson, M.; Smyrnakis, J.; Magiropoulos, M.; Kavoulakis, G. M.

    2017-01-01

    Motivated by numerous experiments on Bose-Einstein condensed atoms which have been performed in tight trapping potentials of various geometries [elongated and/or toroidal (annular)], we develop a general method which allows us to reduce the corresponding three-dimensional Gross-Pitaevskii equation for the order parameter into an effectively one-dimensional equation, taking into account the interactions (i.e., treating the width of the transverse profile variationally) and the curvature of the trapping potential. As an application of our model we consider atoms which rotate in a toroidal trapping potential. We evaluate the state of lowest energy for a fixed value of the angular momentum within various approximations of the effectively one-dimensional model and compare our results with the full solution of the three-dimensional problem, thus getting evidence for the accuracy of our model.

  8. Approaching Bose-Einstein Condensation

    ERIC Educational Resources Information Center

    Ferrari, Loris

    2011-01-01

    Bose-Einstein condensation (BEC) is discussed at the level of an advanced course of statistical thermodynamics, clarifying some formal and physical aspects that are usually not covered by the standard pedagogical literature. The non-conventional approach adopted starts by showing that the continuum limit, in certain cases, cancels out the crucial…

  9. Approaching Bose-Einstein Condensation

    ERIC Educational Resources Information Center

    Ferrari, Loris

    2011-01-01

    Bose-Einstein condensation (BEC) is discussed at the level of an advanced course of statistical thermodynamics, clarifying some formal and physical aspects that are usually not covered by the standard pedagogical literature. The non-conventional approach adopted starts by showing that the continuum limit, in certain cases, cancels out the crucial…

  10. Spatially Periodic Structures of an Atomic Bose-Einstein Condensate

    SciTech Connect

    Rozanov, N.N.

    2005-06-15

    The conditions providing the formation of periodic vortex lattices of an interference nature in an atomic Bose-Einstein condensate (i.e., in the absence of rotation of the condensate) are determined. Spatially periodic exact solutions of the nonlocal nonlinear Schroedinger equation (the generalized Gross-Pitaevskii equation) that describes the Bose-Einstein condensate of a dilute gas of alkali metal atoms with due regard for the nonlocality of interatomic interactions are obtained in the form of a set of two or three plane waves. It is shown that periodic vortex lattices can be produced in interference experiments with a Bose-Einstein condensate of a dilute gas of alkali metal atoms.

  11. Bose-Einstein condensation of ^84Sr

    NASA Astrophysics Data System (ADS)

    Natali Martinez de Escobar, Y.; Desalvo, B. J.; Mickelson, P. G.; Yan, M.; Killian, T. C.

    2010-03-01

    We observe Bose-Einstein condensation (BEC) in the alkaline-earth metal atom strontium (Sr). Bosonic ^84Sr possesses ideal collisional properties for efficient evaporative cooling to quantum degeneracy despite not being the isotope of choice due to its unfavorably low natural abundance (0.6%). This newly condensed element offers novel experimental possibilities, such as using an optical Feshbach resonance to tune atom-atom interactions with relatively low atomic losses. Equally exciting theoretical proposals use quantum fluids made of alkaline-earth atoms to create exotic quantum magnetism states and demonstrate quantum computation in optical lattices.

  12. Structural instability of vortices in Bose-Einstein condensates.

    PubMed

    García-Ripoll, J J; Molina-Terriza, G; Pérez-García, V M; Torner, L

    2001-10-01

    In this paper we study a gaseous Bose-Einstein condensate and show the following: (i) A minimum value of the interaction is needed for the existence of stable persistent currents. (ii) Vorticity is not a fundamental invariant of the system, as there exists a conservative mechanism which can destroy a vortex and change its sign. (iii) This mechanism is suppressed by strong interactions.

  13. Bose-Einstein condensation in quantum magnets

    NASA Astrophysics Data System (ADS)

    Zapf, Vivien; Jaime, Marcelo; Batista, C. D.

    2014-04-01

    This article reviews experimental and theoretical work on Bose-Einstein condensation in quantum magnets. These magnets are natural realizations of gases of interacting bosons whose relevant parameters such as dimensionality, lattice geometry, amount of disorder, nature of the interactions, and particle concentration can vary widely between different compounds. The particle concentration can be easily tuned by applying an external magnetic field which plays the role of a chemical potential. This rich spectrum of realizations offers a unique possibility for studying the different physical behaviors that emerge in interacting Bose gases from the interplay between their relevant parameters. The plethora of other bosonic phases that can emerge in quantum magnets, of which the Bose-Einstein condensate is the most basic ground state, is reviewed. The compounds discussed in this review have been intensively studied in the last two decades and have led to important contributions in the area of quantum magnetism. In spite of their apparent simplicity, these systems often exhibit surprising behaviors. The possibility of using controlled theoretical approaches has triggered the discovery of unusual effects induced by frustration, dimensionality, or disorder.

  14. The management of matter rogue waves in F = 1 spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Loomba, Shally

    2015-06-01

    We have reported the matter rogue wave solutions for the nonautonomous three coupled Gross-Pitaevskii (GP) equation which governs the pulse propagation in spin-1 Bose-Einstein condensates (BECs) with time modulated nonlinearities. The system under consideration has attractive mean-field interactions and ferromagnetic spin-exchange interactions. The exact solutions have been worked out by using similarity and scaling transformations. We have depicted the controllable center characteristics of rogue waves for the kink-type spin-exchange interactions. Additionally, we have also discussed the management of rogue waves for the hyperbolic form of spin-exchange interactions by invoking isospectral Hamiltonian deformation technique.

  15. Exact solutions for generalized variable-coefficients Ginzburg-Landau equation: Application to Bose-Einstein condensates with multi-body interatomic interactions

    NASA Astrophysics Data System (ADS)

    Kengne, E.; Lakhssassi, A.; Vaillancourt, R.; Liu, Wu-Ming

    2012-12-01

    We present a double-mapping method (D-MM), a natural combination of a similarity with F-expansion methods, for obtaining general solvable nonlinear evolution equations. We focus on variable-coefficients complex Ginzburg-Landau equations (VCCGLE) with multi-body interactions. We show that it is easy by this method to find a large class of exact solutions of Gross-Pitaevskii and Gross-Pitaevskii-Ginzburg equations. We apply the D-MM to investigate the dynamics of Bose-Einstein condensation with two- and three-body interactions. As a surprising result, we obtained that it is very easy to use the built D-MM to obtain a large class of exact solutions of VCCGLE with two-body interactions via a generalized VCCGLE with two- and three-body interactions containing cubic-derivative terms. The results show that the proposed method is direct, concise, elementary, and effective, and can be a very effective and powerful mathematical tool for solving many other nonlinear evolution equations in physics.

  16. Exciton polaritons in two-dimensional dichalcogenide layers placed in a planar microcavity: Tunable interaction between two Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Vasilevskiy, Mikhail I.; Santiago-Pérez, Darío G.; Trallero-Giner, Carlos; Peres, Nuno M. R.; Kavokin, Alexey

    2015-12-01

    Exciton-polariton modes arising from interaction between bound excitons in monolayer thin semiconductor sheets and photons in a Fabry-Perot microcavity are considered theoretically. We calculate the dispersion curves, mode lifetimes, Rabi splitting, and Hopfield coefficients of these structures for two nearly 2D semiconductor materials, MoS2 and WS2, and suggest that they are interesting for studying the rich physics associated with the Bose-Einstein condensation of exciton polaritons. The large exciton binding energy and dipole allowed exciton transitions, in addition to the relatively easily controllable distance between the semiconductor sheets, are the advantages of this system in comparison with traditional GaAs or CdTe based semiconductor microcavities. In particular, in order to mimic the rich physical properties of the quantum degenerate mixture of two bosonic species of dilute atomic gases with tunable interspecies interaction, we put forward a structure containing two semiconductor sheets separated by some atomic-scale distance (l ) using a nearly 2D dielectric (e.g., h-BN), which offers the possibility of tuning the interaction between two exciton-polariton Bose-Enstein condensates. We show that the dynamics of this structure are ruled by two coupled Gross-Pitaevskii equations with the coupling parameter ˜l-1 .

  17. Transport of the repulsive Bose-Einstein condensate in a double-well trap: interaction impact and relation to the Josephson effect

    NASA Astrophysics Data System (ADS)

    Nesterenko, V. O.; Novikov, A. N.; Suraud, E.

    2014-12-01

    Two aspects of the transport of a repulsive Bose-Einstein condensate (BEC) in a double-well trap are inspected: The impact of the interatomic interaction and the analogy with the Josephson effect. The analysis employs a numerical solution of a 3D time-dependent Gross-Pitaevskii equation for a total order parameter covering the whole trap. The population transfer is driven by a time-dependent shift of a barrier separating the left and right wells. The sharp and soft profiles of the barrier velocity are tested. The evolution of the relevant characteristics, involving phase differences and currents, is inspected. It is shown that the repulsive interaction substantially supports the transfer making it possible (i) in a wide velocity interval and (ii) three orders of magnitude faster than in the ideal BEC. The transport can be approximately treated as the dc Josephson effect. The dual origin of the critical barrier velocity (break of the adiabatic following and dc/ac transition) is discussed. Following the calculations, the robustness of the transport (dc) crucially depends on the interaction and barrier velocity profile. Only soft profiles which minimize undesirable dipole oscillations are acceptable.

  18. CGC/saturation approach for high energy soft interactions: `soft' Pomeron structure and vn in hadron and nucleus collisions from Bose-Einstein correlations

    NASA Astrophysics Data System (ADS)

    Gotsman, E.; Levin, E.; Maor, U.

    2016-11-01

    In the framework of our model of soft interactions at high energy based on the CGC/saturation approach, we show that Bose-Einstein correlations of identical gluons lead to large values of v_n. We demonstrate how three dimensional scales of high energy interactions, hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of v_n. Our calculation shows that the structure of the `dressed' Pomeron leads to values of v_n which are close to experimental values for proton-proton scattering, 20 % smaller than the observed values for proton-lead collisions and close to lead-lead collisions for 0-10 % centrality. Bearing this result in mind, we conclude that it is premature to consider that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark-gluon plasma.

  19. Localized nonlinear matter waves in two-component Bose-Einstein condensates with time- and space-modulated nonlinearities

    SciTech Connect

    Wang Dengshan; Hu Xinghua; Liu, W. M.

    2010-08-15

    We investigate the localized nonlinear matter waves in the two-component Bose-Einstein condensates with time- and space-modulated nonlinearities analytically and numerically. The similarity transformations are developed to solve the coupled Gross-Pitaevskii equations and two families of explicitly exact solutions are derived. Our results show that not only the attractive spatiotemporal inhomogeneous interactions but the repulsive ones support novel localized nonlinear matter waves in two-component Bose-Einstein condensates. The dynamics of these matter waves, including the breathing solitons, quasibreathing solitons, resonant solitons, and moving solitons, is discussed. We confirm the stability of the exact solutions by adding various initial stochastic noise and study the general cases of the interaction parameters numerically. We also provide the experimental parameters to produce these phenomena in future experiments.

  20. Basic Mean-Field Theory for Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Kevrekidis, P. G.; Frantzeskakis, D. J.; Carretero-González, R.

    The phenomenon of Bose-Einstein condensation, initially predicted by Bose [1] and Einstein [2, 3] in 1924, refers to systems of particles obeying the Bose statistics. In particular, when a gas of bosonic particles is cooled below a critical transition temperature T c , the particles merge into the Bose-Einstein condensate (BEC), in which a macroscopic number of particles (typically 103 to 106) share the same quantum state. Bose-Einstein condensation is in fact a quantum phase transition, which is connected to the manifestation of fundamental physical phenomena, such as superfluidity in liquid helium and superconductivity in metals (see, e.g., [4] for a relevant discussion and references). Dilute weakly-interacting BECs were first realized experimentally in 1995 in atomic gases, and specifically in vapors of rubidium [5] and sodium [6]. In the same year, first signatures of Bose-Einstein condensation in vapors of lithium were also reported [7] and were later more systematically confirmed [8]. The significance and importance of the emergence of BECs has been recognized through the 2001 Nobel prize in Physics [9, 10]. During the last years there has been an explosion of interest in the physics of BECs. Today, over fifty experimental groups around the world can routinely produce BECs, while an enormous amount of theoretical work has ensued.

  1. Dispersive interaction of a Bose-Einstein condensate with a movable mirror of an optomechanical cavity in the presence of laser phase noise

    NASA Astrophysics Data System (ADS)

    Dalafi, A.; Naderi, M. H.

    2016-12-01

    We theoretically investigate the dispersive interaction of a Bose-Einstein condensate (BEC) trapped inside an optomechanical cavity with a moving end mirror in the presence of the laser phase noise (LPN) as well as the atomic collisions. We assume that the effective frequency of the optical mode is much greater than those of the mechanical and the Bogoliubov modes of the movable mirror and the BEC. In the adiabatic approximation where the damping rate of the cavity is faster than those of the other modes, the system behaves as an effective two-mode model in which the atomic and mechanical modes are coupled to each other through the mediation of the optical field by an effective coupling parameter. We show that in the effective two-mode model, the LPN appears as a classical stochastic pump term which drives the amplitude quadratures of the mechanical and the Bogoliubov modes. It is also shown that a strong stationary mirror-atom entanglement can be established just in the dispersive and Doppler regimes where the two modes come into resonance with each other and the effect of the LPN gets very small.

  2. Bose-Einstein condensates in the presence of a magnetic trap and optical lattice.

    PubMed

    Kapitula, Todd; Kevrekidis, P G

    2005-09-01

    In this paper we consider solutions of a nonlinear Schrodinger equation with a parabolic and a periodic potential motivated from the dynamics of Bose-Einstein condensates. Our starting point is the corresponding linear problem which we analyze through regular perturbation and homogenization techniques. We then use Lyapunov-Schmidt theory to establish the persistence and bifurcation of the linear states in the presence of attractive and repulsive nonlinear inter-particle interactions. Stability of such solutions is also examined and a count is given of the potential real, complex and imaginary eigenvalues with negative Krein signature that such solutions may possess. The results are corroborated with numerical computations.

  3. Collapse of a Bose-Einstein condensate induced by fluctuations of the laser intensity

    SciTech Connect

    Garnier, J.; Abdullaev, F.Kh.; Baizakov, B.B.

    2004-05-01

    The dynamics of a metastable attractive Bose-Einstein condensate trapped by a system of laser beams is analyzed in the presence of small fluctuations of the laser intensity. It is shown that the condensate will eventually collapse. The expected collapse time is inversely proportional to the integrated covariance of the time autocorrelation function of the laser intensity and it decays logarithmically with the number of atoms. Numerical simulations of the stochastic three-dimensional Gross-Pitaevskii equation confirm analytical predictions for small and moderate values of mean-field interaction.

  4. Modulation instability and solitary-wave formation in two-component Bose-Einstein condensates

    SciTech Connect

    Kasamatsu, Kenichi; Tsubota, Makoto

    2006-07-15

    We investigate nonlinear dynamics induced by the modulation instability of a two-component mixture in an atomic Bose-Einstein condensate. The nonlinear dynamics is examined using numerical simulations of the time-dependent coupled Gross-Pitaevskii equations. The unstable modulation grows from initially miscible condensates into various types of vector solitary waves, depending on the combinations of the sign of the coupling constants (intracomponent and intercomponent). We discuss the detailed features of the modulation instability, dynamics of solitary wave formation, and an analogy with the collapsing dynamics in a single-component condensate with attractive interactions.

  5. Dynamics of two coupled Bose-Einstein Condensate solitons in an optical lattice.

    PubMed

    Cheng, Yongshan; Gong, Rongzhou; Li, Hong

    2006-04-17

    The characteristics of two coupled Bose-Einstein Condensate (BEC) bright solitons trapped in an optical lattice are investigated with the variational approach and direct numerical simulations of the Gross-Pitaevskii equation. It is found that the optical lattice can be controllably used to capture and drag the coupled BEC solitons. Its effect depends on the initial location of the BEC solitons, the lattice amplitude and wave-number, and the amplitude of the coupled BEC solitons. The effective interaction between the two coupled solitons is the attractive effect.

  6. Collapse and three-body loss in a 85Rb Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Altin, P. A.; Dennis, G. R.; McDonald, G. D.; Döring, D.; Debs, J. E.; Close, J. D.; Savage, C. M.; Robins, N. P.

    2011-09-01

    Collapsing Bose-Einstein condensates are rich and complex quantum systems for which quantitative explanation by simple models has proved elusive. We present experimental data on the collapse of high-density 85Rb condensates with attractive interactions and find quantitative agreement with the predictions of the Gross-Pitaevskii equation. The collapse data and measurements of the decay of atoms from our condensates allow us to put new limits on the value of the 85Rb three-body loss coefficient K3 at small positive and negative scattering lengths.

  7. Collapse and three-body loss in a {sup 85}Rb Bose-Einstein condensate

    SciTech Connect

    Altin, P. A.; Dennis, G. R.; McDonald, G. D.; Doering, D.; Debs, J. E.; Close, J. D.; Savage, C. M.; Robins, N. P.

    2011-09-15

    Collapsing Bose-Einstein condensates are rich and complex quantum systems for which quantitative explanation by simple models has proved elusive. We present experimental data on the collapse of high-density {sup 85}Rb condensates with attractive interactions and find quantitative agreement with the predictions of the Gross-Pitaevskii equation. The collapse data and measurements of the decay of atoms from our condensates allow us to put new limits on the value of the {sup 85}Rb three-body loss coefficient K{sub 3} at small positive and negative scattering lengths.

  8. Chaos control of a Bose-Einstein condensate in a moving optical lattice

    NASA Astrophysics Data System (ADS)

    Zhang, Zhiying; Feng, Xiuqin; Yao, Zhihai

    2016-07-01

    Chaos control of a Bose-Einstein condensate (BEC) loaded into a moving optical lattice with attractive interaction is investigated on the basis of Lyapunov stability theory. Three methods are designed to control chaos in BEC. As a controller, a bias constant, periodic force, or wavelet function feedback is added to the BEC system. Numerical simulations reveal that chaotic behavior can be well controlled to achieve periodicity by regulating control parameters. Different periodic orbits are available for different control parameters only if the maximal Lyapunov exponent of the system is negative. The abundant effect of chaotic control is also demonstrated numerically. Chaos control can be realized effectively by using our proposed control strategies.

  9. Effective Action for Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Kita, Takafumi

    2014-06-01

    We clarify basic properties of an effective action (i.e., self-consistent perturbation expansion) for interacting Bose-Einstein condensates, where field ψ itself acquires a finite thermodynamic average < ψ > besides two-point Green's function hat{G} to form an off-diagonal long-range order. It is shown that the action can be expressed concisely order by order in terms of the interaction vertex and a special combination of < ψ > and hat{G} so as to satisfy both Noether's theorem and Goldstone's theorem (I) corresponding to the first proof. The self-energy is predicted to have a one-particle-reducible structure due to < ψ > ≠ 0 to transform the Bogoliubov mode into a bubbling mode with a substantial decay rate.

  10. Vortex-Antivortex-Pair Lattices in Spin-Orbit Coupled Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Li, Ben; Sakaguchi, Hidetsugu

    2014-04-01

    We investigate theoretically the ground states of Bose-Einstein condensates with Rashba spin-orbit coupling in optical lattices within mean-field framework. We obtain numerically the Bloch states and energy spectrum for the single particle Hamiltonian, meanwhile the analytical solution of Bloch states is also presented. For a spin-orbit coupling Bose-Einstein condensates with a weak interaction, we show the existence of the vortex-antivortex-pair lattices state by simulating the Gross-Pitaevskii equation.

  11. Steady-state entanglement of a Bose-Einstein condensate and a nanomechanical resonator

    SciTech Connect

    Asjad, Muhammad; Saif, Farhan

    2011-09-15

    We analyze the steady-state entanglement between Bose-Einstein condensate trapped inside an optical cavity with a moving end mirror (nanomechanical resonator) driven by a single mode laser. The quantized laser field mediates the interaction between the Bose-Einstein condensate and nanomechanical resonator. In particular, we study the influence of temperature on the entanglement of the coupled system, and note that the steady-state entanglement is fragile with respect to temperature.

  12. Controllable scattering of vector Bose-Einstein solitons

    SciTech Connect

    Babarro, Judit; Paz-Alonso, Maria J.; Michinel, Humberto; Salgueiro, Jose R.; Olivieri, David N.

    2005-04-01

    We show the possibility of producing matter-wave switching devices by using Manakov interactions between vector matter-wave solitons using two-species Bose-Einstein condensates (BECs). Our results establish the experimental parameters for three interaction regimes in two-species BECs: symmetric and asymmetric splitting, down-switching, and up-switching. We have studied the dependence upon the initial conditions and the kind of interaction between the two matter-wave solitons.

  13. Recent developments in Bose-Einstein condensation

    SciTech Connect

    Kalman, G.

    1997-09-22

    This paper contains viewgraphs on developments on Bose-Einstein condensation. Some topics covered are: strongly coupled coulomb systems; standard response functions of the first and second kind; dynamical mean field theory; quasi localized charge approximation; and the main equations.

  14. Forming a Bose-Einstein Condensate

    NASA Image and Video Library

    2014-09-26

    This sequence of false-color images shows the formation of a Bose-Einstein condensate in the Cold Atom Laboratory prototype at NASA Jet Propulsion Laboratory as the temperature gets progressively closer to absolute zero.

  15. Scalar field as a Bose-Einstein condensate?

    NASA Astrophysics Data System (ADS)

    Castellanos, Elías; Escamilla-Rivera, Celia; Macías, Alfredo; Núñez, Darío

    2014-11-01

    We discuss the analogy between a classical scalar field with a self-interacting potential, in a curved spacetime described by a quasi-bounded state, and a trapped Bose-Einstein condensate. In this context, we compare the Klein-Gordon equation with the Gross-Pitaevskii equation. Moreover, the introduction of a curved background spacetime endows, in a natural way, an equivalence to the Gross-Pitaevskii equation with an explicit confinement potential. The curvature also induces a position dependent self-interaction parameter. We exploit this analogy by means of the Thomas-Fermi approximation, commonly used to describe the Bose-Einstein condensate, in order to analyze the quasi bound scalar field distribution surrounding a black hole.

  16. Scalar field as a Bose-Einstein condensate?

    SciTech Connect

    Castellanos, Elías; Escamilla-Rivera, Celia; Macías, Alfredo; Núñez, Darío E-mail: cescamilla@mctp.mx E-mail: nunez@nucleares.unam.mx

    2014-11-01

    We discuss the analogy between a classical scalar field with a self-interacting potential, in a curved spacetime described by a quasi-bounded state, and a trapped Bose-Einstein condensate. In this context, we compare the Klein-Gordon equation with the Gross-Pitaevskii equation. Moreover, the introduction of a curved background spacetime endows, in a natural way, an equivalence to the Gross-Pitaevskii equation with an explicit confinement potential. The curvature also induces a position dependent self-interaction parameter. We exploit this analogy by means of the Thomas-Fermi approximation, commonly used to describe the Bose-Einstein condensate, in order to analyze the quasi bound scalar field distribution surrounding a black hole.

  17. Topological Winding and Unwinding in Metastable Bose-Einstein Condensates

    SciTech Connect

    Kanamoto, Rina; Carr, Lincoln D.; Ueda, Masahito

    2008-02-15

    Topological winding and unwinding in a quasi-one-dimensional metastable Bose-Einstein condensate are shown to be manipulated by changing the strength of interaction or the frequency of rotation. Exact diagonalization analysis reveals that quasidegenerate states emerge spontaneously near the transition point, allowing a smooth crossover between topologically distinct states. On a mean-field level, the transition is accompanied by formation of gray solitons, or density notches, which serve as an experimental signature of this phenomenon.

  18. Many-particle entanglement with Bose-Einstein condensates.

    PubMed

    Sørensen, A; Duan, L M; Cirac, J I; Zoller, P

    2001-01-04

    The possibility of creating and manipulating entangled states of systems of many particles is of significant interest for quantum information processing; such a capability could lead to new applications that rely on the basic principles of quantum mechanics. So far, up to four atoms have been entangled in a controlled way. A crucial requirement for the production of entangled states is that they can be considered pure at the single-particle level. Bose-Einstein condensates fulfil this requirement; hence it is natural to investigate whether they can also be used in some applications of quantum information. Here we propose a method to achieve substantial entanglement of a large number of atoms in a Bose-Einstein condensate. A single resonant laser pulse is applied to all the atoms in the condensate, which is then allowed to evolve freely; in this latter stage, collisional interactions produce entanglement between the atoms. The technique should be realizable with present technology.

  19. Vortex dynamics in coherently coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Calderaro, Luca; Fetter, Alexander L.; Massignan, Pietro; Wittek, Peter

    2017-02-01

    In classical hydrodynamics with uniform density, vortices move with the local fluid velocity. This description is rewritten in terms of forces arising from the interaction with other vortices. Two such positive straight vortices experience a repulsive interaction and precess in a positive (anticlockwise) sense around their common centroid. A similar picture applies to vortices in a two-component, two-dimensional uniform Bose-Einstein condensate (BEC) coherently coupled through rf Rabi fields. Unlike the classical case, however, the rf Rabi coupling induces an attractive interaction and two such vortices with positive signs now rotate in the negative (clockwise) sense. Pairs of counter-rotating vortices are instead found to translate with uniform velocity perpendicular to the line joining their cores. This picture is extended to a single vortex in a two-component trapped BEC. Although two uniform vortex-free components experience familiar Rabi oscillations of particle-number difference, such behavior is absent for a vortex in one component because of the nonuniform vortex phase. Instead the coherent Rabi coupling induces a periodic vorticity transfer between the two components.

  20. Bose-Einstein condensation and indirect excitons: a review

    NASA Astrophysics Data System (ADS)

    Combescot, Monique; Combescot, Roland; Dubin, François

    2017-06-01

    We review recent progress on Bose-Einstein condensation (BEC) of semiconductor excitons. The first part deals with theory, the second part with experiments. This Review is written at a time where the problem of exciton Bose-Einstein condensation has just been revived by the understanding that the exciton condensate must be dark because the exciton ground state is not coupled to light. Here, we theoretically discuss this missed understanding before providing its experimental support through experiments that scrutinize indirect excitons made of spatially separated electrons and holes. The theoretical part first discusses condensation of elementary bosons. In particular, the necessary inhibition of condensate fragmentation by exchange interaction is stressed, before extending the discussion to interacting bosons with spin degrees of freedom. The theoretical part then considers composite bosons made of two fermions like semiconductor excitons. The spin structure of the excitons is detailed, with emphasis on the crucial fact that ground-state excitons are dark: indeed, this imposes the exciton Bose-Einstein condensate to be not coupled to light in the dilute regime. Condensate fragmentations are then reconsidered. In particular, it is shown that while at low density, the exciton condensate is fully dark, it acquires a bright component, coherent with the dark one, beyond a density threshold: in this regime, the exciton condensate is ‘gray’. The experimental part first discusses optical creation of indirect excitons in quantum wells, and the detection of their photoluminescence. Exciton thermalisation is also addressed, as well as available approaches to estimate the exciton density. We then switch to specific experiments where indirect excitons form a macroscopic fragmented ring. We show that such ring provides efficient electrostatic trapping in the region of the fragments where an essentially-dark exciton Bose-Einstein condensate is formed at sub-Kelvin bath

  1. Bose-Einstein condensation and indirect excitons: a review.

    PubMed

    Combescot, Monique; Combescot, Roland; Dubin, François

    2017-06-01

    We review recent progress on Bose-Einstein condensation (BEC) of semiconductor excitons. The first part deals with theory, the second part with experiments. This Review is written at a time where the problem of exciton Bose-Einstein condensation has just been revived by the understanding that the exciton condensate must be dark because the exciton ground state is not coupled to light. Here, we theoretically discuss this missed understanding before providing its experimental support through experiments that scrutinize indirect excitons made of spatially separated electrons and holes. The theoretical part first discusses condensation of elementary bosons. In particular, the necessary inhibition of condensate fragmentation by exchange interaction is stressed, before extending the discussion to interacting bosons with spin degrees of freedom. The theoretical part then considers composite bosons made of two fermions like semiconductor excitons. The spin structure of the excitons is detailed, with emphasis on the crucial fact that ground-state excitons are dark: indeed, this imposes the exciton Bose-Einstein condensate to be not coupled to light in the dilute regime. Condensate fragmentations are then reconsidered. In particular, it is shown that while at low density, the exciton condensate is fully dark, it acquires a bright component, coherent with the dark one, beyond a density threshold: in this regime, the exciton condensate is 'gray'. The experimental part first discusses optical creation of indirect excitons in quantum wells, and the detection of their photoluminescence. Exciton thermalisation is also addressed, as well as available approaches to estimate the exciton density. We then switch to specific experiments where indirect excitons form a macroscopic fragmented ring. We show that such ring provides efficient electrostatic trapping in the region of the fragments where an essentially-dark exciton Bose-Einstein condensate is formed at sub-Kelvin bath

  2. Hubbard Model for Atomic Impurities Bound by the Vortex Lattice of a Rotating Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Johnson, T. H.; Yuan, Y.; Bao, W.; Clark, S. R.; Foot, C.; Jaksch, D.

    2016-06-01

    We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes.

  3. Hubbard Model for Atomic Impurities Bound by the Vortex Lattice of a Rotating Bose-Einstein Condensate.

    PubMed

    Johnson, T H; Yuan, Y; Bao, W; Clark, S R; Foot, C; Jaksch, D

    2016-06-17

    We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes.

  4. Bose-Einstein condensation of light: general theory.

    PubMed

    Sob'yanin, Denis Nikolaevich

    2013-08-01

    A theory of Bose-Einstein condensation of light in a dye-filled optical microcavity is presented. The theory is based on the hierarchical maximum entropy principle and allows one to investigate the fluctuating behavior of the photon gas in the microcavity for all numbers of photons, dye molecules, and excitations at all temperatures, including the whole critical region. The master equation describing the interaction between photons and dye molecules in the microcavity is derived and the equivalence between the hierarchical maximum entropy principle and the master equation approach is shown. The cases of a fixed mean total photon number and a fixed total excitation number are considered, and a much sharper, nonparabolic onset of a macroscopic Bose-Einstein condensation of light in the latter case is demonstrated. The theory does not use the grand canonical approximation, takes into account the photon polarization degeneracy, and exactly describes the microscopic, mesoscopic, and macroscopic Bose-Einstein condensation of light. Under certain conditions, it predicts sub-Poissonian statistics of the photon condensate and the polarized photon condensate, and a universal relation takes place between the degrees of second-order coherence for these condensates. In the macroscopic case, there appear a sharp jump in the degrees of second-order coherence, a sharp jump and kink in the reduced standard deviations of the fluctuating numbers of photons in the polarized and whole condensates, and a sharp peak, a cusp, of the Mandel parameter for the whole condensate in the critical region. The possibility of nonclassical light generation in the microcavity with the photon Bose-Einstein condensate is predicted.

  5. Anderson Localization of a non-interacting Bose-Einstein condensate with effective spin-orbit interaction in a quasiperiodic optical lattice

    NASA Astrophysics Data System (ADS)

    Zhou, Lu; Pu, Han; Zhang, Weiping

    2013-03-01

    We theoretically investigate the localization properties of a noninteracting atomic Bose-Einstein condensate moving in a one-dimensional quasiperiodic optical lattice potential in the tight-binding regime. The atoms are subject to effective spin-orbit coupling induced by external laser fields. We present the phase diagram in the parameter space of the disorder strength and those related to the effective spin-orbit coupling. The phase diagram are verified via multifractal analysis of the atomic wavefunctions. We found that spin-orbit coupling can lead to the spectra mixing (coexistence of extended and localized states) and the appearance of mobility edges. We acknowledge National Natural Science Foundation of China under Grant No 11004057, Shanghai Rising-Star Program under Grant No. 12QA1401000 and the ``Chen Guang'' project under Grant No 10CG24 for financial supports.

  6. Bose-Einstein condensation in atomic alkali gases

    NASA Astrophysics Data System (ADS)

    Dodd, Robert J.

    1998-05-01

    I present a review of the time-independent Gross-Pitaevskii (GP), Bogoliubov, and finite-temperature Hartree-Fock-Bogoliubov (HFB) mean-field theories used to study trapped, Bose-Einstein condensed alkali gases. Numerical solutions of the (zero-temperature) GP equation are presented for attractive (negative scattering length) and repulsive (positive scattering length) interactions. Comparison is made with the Thomas-Fermi and (variational) trial wavefunction appr oximations that are used in the literature to study condensed gases. Numerical calculations of the (zero-temperature) Bogoliubov quasi-particle excitation frequencies are found to be in excellent agreement with the experimental results. The finite-temperature properties of condensed gases are examined using the Popov approximation (of the HFB theory) and a simple two-gas model. Specific, quantitative comparisons are made with experimental results for finite-temperature excitation frequencies. Qualitative comparisons are made between the results of the Popov approximation, two-gas model, and other published models for condensate fraction and thermal density distribution. The time-independent mean-field theories are found to be in excellent agreement with experimental results at relatively low temperatures (high condensate fractions). However, at higher temperatures (and condensate fractions of less than 50%) there are significant discrepancies between experimental data and theoretical calculations. This work was undertaken at the University of Maryland at College Park and was supported in part by the National Science Foundation (PHY-9601261) and the U.S. Office of Naval Research.

  7. Enhancement of spin coherence in a spin-1 Bose-Einstein condensate by dynamical decoupling approaches

    SciTech Connect

    Ning Boyuan; Zhuang Jun; Zhang Wenxian; You, J. Q.

    2011-07-15

    We study the enhancement of spin coherence with periodic, concatenated, or Uhrig dynamical decoupling N-pulse sequences in a spin-1 Bose-Einstein condensate, where the intrinsic dynamical instability in such a ferromagnetically interacting condensate causes spin decoherence and eventually leads to a multiple spatial-domain structure or a spin texture. Our results show that all three sequences successfully enhance the spin coherence by pushing the wave vector of the most unstable mode in the condensate to a larger value. Among the three sequences with the same number of pulses, the concatenated one shows the best performance in preserving the spin coherence. More interestingly, we find that all three sequences exactly follow the same enhancement law, k{sub -}T{sup 1/2}=c, with k{sub -} the wave vector of the most unstable mode, T the sequence period, and c a sequence-dependent constant. Such a law between k{sub -} and T is also derived analytically for an attractive scalar Bose-Einstein condensate subjected to a periodic dynamical decoupling sequence.

  8. Engineering bright solitons to enhance the stability of two-component Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Radha, R.; Vinayagam, P. S.; Sudharsan, J. B.; Liu, Wu-Ming; Malomed, Boris A.

    2015-12-01

    We consider a system of coupled Gross-Pitaevskii (GP) equations describing a binary quasi-one-dimensional Bose-Einstein condensate (BEC) with intrinsic time-dependent attractive interactions, placed in a time-dependent expulsive parabolic potential, in a special case when the system is integrable (a deformed Manakov's system). Since the nonlinearity in the integrable system which represents binary attractive interactions exponentially decays with time, solitons are also subject to decay. Nevertheless, it is shown that the robustness of bright solitons can be enhanced in this system, making their respective lifetime longer, by matching the time dependence of the interaction strength (adjusted with the help of the Feshbach-resonance management) to the time modulation of the strength of the parabolic potential. The analytical results, and their stability, are corroborated by numerical simulations. In particular, we demonstrate that the addition of random noise does not impact the stability of the solitons.

  9. Bright solitons in a two-dimensional spin-orbit-coupled dipolar Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Xu, Yong; Zhang, Yongping; Zhang, Chuanwei

    2015-07-01

    We study a two-dimensional spin-orbit-coupled dipolar Bose-Einstein condensate with repulsive contact interactions by both the variational method and the imaginary-time evolution of the Gross-Pitaevskii equation. The dipoles are completely polarized along one direction in the two-dimensional plane to provide an effective attractive dipole-dipole interaction. We find two types of solitons as the ground states arising from such attractive dipole-dipole interactions: a plane-wave soliton with a spatially varying phase and a stripe soliton with a spatially oscillating density for each component. Both types of solitons possess smaller size and higher anisotropy than the soliton without spin-orbit coupling. Finally, we discuss the properties of moving solitons, which are nontrivial because of the violation of Galilean invariance.

  10. Interaction-Assisted Quantum Tunneling of a Bose-Einstein Condensate Out of a Single Trapping Well.

    PubMed

    Potnis, Shreyas; Ramos, Ramon; Maeda, Kenji; Carr, Lincoln D; Steinberg, Aephraim M

    2017-02-10

    We experimentally study tunneling of Bose-condensed ^{87}Rb atoms prepared in a quasibound state and observe a nonexponential decay caused by interatomic interactions. A combination of a magnetic quadrupole trap and a thin 1.3  μm barrier created using a blue-detuned sheet of light is used to tailor traps with controllable depth and tunneling rate. The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes-classical spilling over the barrier, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate depends exponentially on the chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.

  11. Interaction-Assisted Quantum Tunneling of a Bose-Einstein Condensate Out of a Single Trapping Well

    NASA Astrophysics Data System (ADS)

    Potnis, Shreyas; Ramos, Ramon; Maeda, Kenji; Carr, Lincoln D.; Steinberg, Aephraim M.

    2017-02-01

    We experimentally study tunneling of Bose-condensed Rb 87 atoms prepared in a quasibound state and observe a nonexponential decay caused by interatomic interactions. A combination of a magnetic quadrupole trap and a thin 1.3 μ m barrier created using a blue-detuned sheet of light is used to tailor traps with controllable depth and tunneling rate. The escape dynamics strongly depend on the mean-field energy, which gives rise to three distinct regimes—classical spilling over the barrier, quantum tunneling, and decay dominated by background losses. We show that the tunneling rate depends exponentially on the chemical potential. Our results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.

  12. Collisions of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Reinhardt, William P.; Clark, Charles W.

    1997-03-01

    Recent experiments(N. J. van Druten et al.), preprint (1996) have begun to study collisions of dilute Bose-Einstein condensates (BECs), and we are exploring BEC collisional phenomena in a simplified model. Two BECs are separated by a barrier, which is dropped to allow them to interact; in the initial configuration, the two BECs may have different phases. Time evolution is described by numerically solving the time-dependent nonlinear Schrödinger equation for a BEC confined by hard walls in a region of constant external potential. We find that zero--energy collisions between ground state condensates that are separately prepared, and then juxtaposed, are dominated by solitons, and that soliton properties are controlled by the phase difference and initial separation of the colliding condensates. The basic ideas of Anderson(P. W. Anderson, Basic Notions of Condensed Matter Physics) (Addison Wesley, Reading, MA, 1984) p. 18 relating to phase rigidity of ``cold quantum matter'' display themselves in a robust manner; this suggests the inevitability of Josephson-type effects for artificially separated but weakly interacting BEC ground states. Partial results are presented in remote figures. goes between the ; the system generates the footnote number.

  13. Bose-Einstein condensation. Twenty years after

    SciTech Connect

    Bagnato, V. S.; Frantzeskakis, D. J.; Kevrekidis, P. G.; Malomed, B. A.; Mihalache, D.

    2015-02-23

    The aim of this introductory article is two-fold. First, we aim to offer a general introduction to the theme of Bose-Einstein condensates, and briefly discuss the evolution of a number of relevant research directions during the last two decades. Second, we introduce and present the articles that appear in this Special Volume of Romanian Reports in Physics celebrating the conclusion of the second decade since the experimental creation of Bose-Einstein condensation in ultracold gases of alkali-metal atoms.

  14. Dynamical properties of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Navarro, Rafael

    Bose-Einstein condensates (BECs) provide a testbed for a wide array of coherent structures with complex dynamical properties. Of these structures, vortices and two-component BECs are at the forefront in understanding fundamental properties of BECs and have been under intense scrutiny in both experiments and theoretical studies. The behavior of these structures elucidates the mechanics of nonlinear processes that give rise to patterns in vortex lattices and patterns in binary BECs. This has lead to the integration of BECs into the new field of emergent phenomena that has unified many seemingly unrelated disciplines because at a fundamental level, the nonlinear processes provide a blueprint to give rise to coherence out of randomness. First, we study the interactions between two atomic species in a binary BEC to determine conditions for miscibility, oscillations between species, steady state solutions and their stability. Second, the two component system is extended to a quasi-2D systems for a pancake-shaped condensate. Third, the shape of the background atomic density as well as the background with a vortex is studied to determine the role of the phase and background on the precession of a vortex. Lastly, the dynamics of small clusters of same charge vortices in a trapped BEC is studied giving fixed point configurations that rotate at a constant speed.

  15. Bose-Einstein Condensation in low dimensionality

    NASA Astrophysics Data System (ADS)

    Nho, Kwangsik; Landau, D. P.

    2006-03-01

    Using path integral Monte Carlo simulation methods[1], we have studied properties of Bose-Einstein Condensates harmonically trapped in low dimemsion. Each boson has a hard-sphere potential whose core radius equals its corresponding scattering length. We have tightly confined the motion of trapped particles in one or more direction by increasing the trap anisotropy in order to simulate lower dimensional atomic gases. We have investigated the effect of both the temperature and the dimemsionality on the energetics and structural properties such as the total energy, the density profile, and the superfluid fraction. Our results show that the physics of low dimensional bosonic systems is very different from that of their three dimensional counterparts[2]. The superfluid fraction for a quasi-2D boson gas decreases faster than that for both a quasi-1D system[3] and a true 3D system with increasing temperature. The superfluid fraction decreases gradually as the two-body interaction strength increases although it shows no noticable dependence for both a quasi-1D system and a true 3D system. [1] K. Nho and D. P. Landau, Phys. Rev. A. 70, 53614 (2004).[2] N. D. Mermin and H. Wagner, Phys. Rev. Lett. 22, 1133 (1966);1.5inP. C. Hohenberg, Phys. Rev. 158, 383 (1967).[3] K. Nho and D. Blume, Phys. Rev. Lett. 95, 193601 (2005).

  16. Controlling chaos of a Bose-Einstein condensate loaded into a moving optical Fourier-synthesized lattice.

    PubMed

    Chacón, R; Bote, D; Carretero-González, R

    2008-09-01

    We study the chaotic properties of steady-state traveling-wave solutions of the particle number density of a Bose-Einstein condensate with an attractive interatomic interaction loaded into a traveling optical lattice of variable shape. We demonstrate theoretically and numerically that chaotic traveling steady states can be reliably suppressed by small changes of the traveling optical lattice shape while keeping the remaining parameters constant. We find that the regularization route as the optical lattice shape is continuously varied is fairly rich, including crisis phenomena and period-doubling bifurcations. The conditions for a possible experimental realization of the control method are discussed.

  17. Observation of Weak Collapse in a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Eigen, Christoph; Gaunt, Alexander L.; Suleymanzade, Aziza; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P.

    2016-10-01

    We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential of an optical-box trap. We characterize the critical point for collapse and the collapse dynamics, observing universal behavior in agreement with theoretical expectations. Most importantly, we observe a clear experimental signature of the counterintuitive weak collapse, namely, that making the system more unstable can result in a smaller particle loss. We experimentally determine the scaling laws that govern the weak-collapse atom loss, providing a benchmark for the general theories of nonlinear wave phenomena.

  18. Soliton-soliton scattering in dipolar Bose-Einstein condensates

    SciTech Connect

    Nath, R.; Santos, L.; Pedri, P.

    2007-07-15

    We analyze the scattering of bright solitons in dipolar Bose-Einstein condensates placed in unconnected layers. Whereas for short-range interactions unconnected layers are independent, a remarkable consequence of the dipole interaction is the appearance of nonlocal interlayer effects. In particular, we show that both for one- and two-dimensional solitons the interlayer interaction leads to an effective molecular potential between disconnected solitons, which induces a complex scattering physics between them, that includes inelastic fusion into soliton molecules, and strong inelastic resonances. In addition, contrary to the short-range interacting case, a two-dimensional soliton scattering is possible, in which inelastic spiraling occurs, resembling phenomena in photorefractive materials.

  19. Bouncing dynamics of Bose-Einstein condensates under the effects of gravity

    NASA Astrophysics Data System (ADS)

    Sekh, Golam Ali

    2017-03-01

    Bouncing dynamics of quasi-one dimensional Bose-Einstein condensates (BECs) falling under gravity on delta-function potentials is investigated. First, we consider a single component BEC in the presence of cubic-quintic nonlinearity and study dynamical behavior of different parameters of the system using variational and numerical approaches. We see that the quintic nonlinearity plays a dominant role over cubic nonlinear interaction to extend the bouncing dynamics in the non-linear regime. We find that a matter-wave performs bouncing motion only for certain discrete values of initial position above the reflecting potential. We then consider bouncing dynamics of binary BECs. It is shown that the pair of matter-waves bounces together if inter-species interaction is attractive. However, their pairing breaks down if the inter-species interaction is made repulsive.

  20. Crystallized and amorphous vortices in rotating atomic-molecular Bose-Einstein condensates

    PubMed Central

    Liu, Chao-Fei; Fan, Heng; Gou, Shih-Chuan; Liu, Wu-Ming

    2014-01-01

    Vortex is a topological defect with a quantized winding number of the phase in superfluids and superconductors. Here, we investigate the crystallized (triangular, square, honeycomb) and amorphous vortices in rotating atomic-molecular Bose-Einstein condensates (BECs) by using the damped projected Gross-Pitaevskii equation. The amorphous vortices are the result of the considerable deviation induced by the interaction of atomic-molecular vortices. By changing the atom-molecule interaction from attractive to repulsive, the configuration of vortices can change from an overlapped atomic-molecular vortices to carbon-dioxide-type ones, then to atomic vortices with interstitial molecular vortices, and finally into independent separated ones. The Raman detuning can tune the ratio of the atomic vortex to the molecular vortex. We provide a phase diagram of vortices in rotating atomic-molecular BECs as a function of Raman detuning and the strength of atom-molecule interaction. PMID:24573303

  1. Number-conserving master equation theory for a dilute Bose-Einstein condensate

    SciTech Connect

    Schelle, Alexej; Wellens, Thomas; Buchleitner, Andreas; Delande, Dominique

    2011-01-15

    We describe the transition of N weakly interacting atoms into a Bose-Einstein condensate within a number-conserving quantum master equation theory. Based on the separation of time scales for condensate formation and noncondensate thermalization, we derive a master equation for the condensate subsystem in the presence of the noncondensate environment under the inclusion of all two-body interaction processes. We numerically monitor the condensate particle number distribution during condensate formation, and derive a condition under which the unique equilibrium steady state of a dilute, weakly interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal state of N noninteracting atoms.

  2. Einstein, Bose and Bose-Einstein Statistics

    NASA Astrophysics Data System (ADS)

    Wali, Kameshwar C.

    2005-05-01

    In June 1924, a relatively unknown Satyendra Nath Bose from Dacca, India, wrote a letter to Einstein beginning with ``Respected Sir, I have ventured to send you the accompanying article for your perusal. I am anxious to know what you think of it. You will see that I have ventured to deduce the coefficient 8πυ^2/c^3 in Planck's law independent of the classical electrodynamics, only assuming that the ultimate elementary regions in Phase-space have the content h^3. I do not know sufficient German to translate the paper. If you think the paper worth publication, I shall be grateful if you arrange for its publication in Zeitschrift für Physik.'' Einstein did translate the article himself and got it published. He wrote to Ehrenfest: ``The Indian Bose has given a beautiful derivation of Planck's law, including the constant [i.e.8πυ^2/c^3].'' Einstein extended the ideas of Bose that implied, among other things, a new statistics for the light-quanta to the molecules of an ideal gas and wrote to Ehrenfest, `from a certain temperature on, the molecules ``condense'' without attractive forces, that is, they accumulate at zero velocity. The theory is pretty, but is there also some truth to it?' Abraham Pais has called Bose's paper ``the fourth and the last revolutionary papers of the old quantum theory.'' My paper will present the works of Bose and Einstein in their historical perspective and the eventual birth of the new quantum Bose-Einstein statistics.

  3. Spinor dipolar bose-einstein condensates: classical spin approach.

    PubMed

    Takahashi, M; Ghosh, Sankalpa; Mizushima, T; Machida, K

    2007-06-29

    Bose-Einstein condensates which are dominated by magnetic dipole-dipole interaction are discussed under spinful situations. We treat the spin degrees of freedom as a classical spin vector, approaching from the large spin limit to obtain an effective minimal Hamiltonian. This is a version extended from a nonlinear sigma model. By solving the Gross-Pitaevskii equation, we find several novel spin textures where the mass density and spin density are strongly coupled, depending upon trap geometries due to the long-range and anisotropic natures of the dipole-dipole interaction.

  4. Spinor Dipolar Bose-Einstein Condensates: Classical Spin Approach

    SciTech Connect

    Takahashi, M.; Mizushima, T.; Machida, K.; Ghosh, Sankalpa

    2007-06-29

    Bose-Einstein condensates which are dominated by magnetic dipole-dipole interaction are discussed under spinful situations. We treat the spin degrees of freedom as a classical spin vector, approaching from the large spin limit to obtain an effective minimal Hamiltonian. This is a version extended from a nonlinear sigma model. By solving the Gross-Pitaevskii equation, we find several novel spin textures where the mass density and spin density are strongly coupled, depending upon trap geometries due to the long-range and anisotropic natures of the dipole-dipole interaction.

  5. Behaviour of Rotating Bose Einstein Condensates Under Shrinking

    NASA Astrophysics Data System (ADS)

    Zhai, Hui; Zhou, Qi

    2005-01-01

    When the repulsive interaction strength between atoms decreases, the size of a rotating Bose-Einstein condensate will consequently shrink. We find that the rotational frequency will increase during the shrinking of condensate, which is a quantum mechanical analogy to ballet dancing. Compared to a non-rotating condensate, the size of a rotating BEC will eventually be saturated at a finite value when the interaction strength is gradually reduced. We also calculate the vortex dynamics induced by the atomic current, and discuss the difference of vortex dynamics in this case and that observed in a recent experiment carried out by the JILA group [Phys. Rev. Lett. 90 (2003) 170405].

  6. Low Velocity Quantum Reflection of Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Pasquini, T. A.; Saba, M.; Jo, G.-B.; Shin, Y.; Ketterle, W.; Pritchard, D. E.; Savas, T. A.; Mulders, N.

    2006-09-01

    We study how interactions affect the quantum reflection of Bose-Einstein condensates. A patterned silicon surface with a square array of pillars resulted in high reflection probabilities. For incident velocities greater than 2.5mm/s, our observations agreed with single-particle theory. At velocities below 2.5mm/s, the measured reflection probability saturated near 60% rather than increasing towards unity as predicted by the accepted theoretical model. We extend the theory of quantum reflection to account for the mean-field interactions of a condensate which suppresses quantum reflection at low velocity. The reflected condensates show collective excitations as recently predicted.

  7. Matter rogue waves in an F=1 spinor Bose-Einstein condensate.

    PubMed

    Qin, Zhenyun; Mu, Gui

    2012-09-01

    We report new types of matter rogue waves of a spinor (three-component) model of the Bose-Einstein condensate governed by a system of three nonlinearly coupled Gross-Pitaevskii equations. The exact first-order rational solutions containing one free parameter are obtained by means of a Darboux transformation for the integrable system where the mean-field interaction is attractive and the spin-exchange interaction is ferromagnetic. For different choices of the parameter, there exists a variety of different shaped solutions including two peaks in bright rogue waves and four dips in dark rogue waves. Furthermore, by utilizing the relation between the three-component and the one-component versions of the nonlinear Schrödinger equation, we can devise higher-order rational solutions, in which three components have different shapes. In addition, it is noteworthy that dark rogue wave features disappear in the third-order rational solution.

  8. Occupation Statistics of a Bose-Einstein Condensate for a Driven Landau-Zener Crossing

    SciTech Connect

    Smith-Mannschott, Katrina; Chuchem, Maya; Cohen, Doron; Hiller, Moritz; Kottos, Tsampikos

    2009-06-12

    We consider an atomic Bose-Einstein condensate loaded in a biased double-well trap with tunneling rate K and interatomic interaction U. The Bose-Einstein condensate is prepared such that all N atoms are in the left well. We drive the system by sweeping the potential difference E between the two wells. Depending on the interaction u=NU/K and the sweep rate E, we distinguish three dynamical regimes: adiabatic, diabatic, and sudden and consider the occupation statistics of the final state. The analysis goes beyond mean-field theory and is complemented by a semiclassical picture.

  9. Occupation statistics of a Bose-Einstein condensate for a driven Landau-Zener crossing.

    PubMed

    Smith-Mannschott, Katrina; Chuchem, Maya; Hiller, Moritz; Kottos, Tsampikos; Cohen, Doron

    2009-06-12

    We consider an atomic Bose-Einstein condensate loaded in a biased double-well trap with tunneling rate K and interatomic interaction U. The Bose-Einstein condensate is prepared such that all N atoms are in the left well. We drive the system by sweeping the potential difference E between the two wells. Depending on the interaction u=NU/K and the sweep rate E, we distinguish three dynamical regimes: adiabatic, diabatic, and sudden and consider the occupation statistics of the final state. The analysis goes beyond mean-field theory and is complemented by a semiclassical picture.

  10. Bose-Einstein condensation in binary mixture of Bose gases

    SciTech Connect

    Tran Huu Phat; Le Viet Hoa; Nguyen Tuan Anh Nguyen Van Long

    2009-10-15

    The Bose-Einstein condensation (BEC) in a binary mixture of Bose gases is studied by means of the Cornwall-Jackiw-Tomboulis (CJT) effective action approach. The equations of state (EoS) and various scenarios of phase transitions of the system are considered in detail, in particular, the numerical computations are carried out for symmetry restoration (SR), symmetry nonrestoration (SNR) and inverse symmetry breaking (ISB) for getting an insight into their physical nature. It is shown that due to the cross interaction between distinct components of mixture there occur two interesting phenomena: the high temperature BEC and the inverse BEC, which could be tested in experiments.

  11. Brownian motion of solitons in a Bose-Einstein condensate.

    PubMed

    Aycock, Lauren M; Hurst, Hilary M; Efimkin, Dmitry K; Genkina, Dina; Lu, Hsin-I; Galitski, Victor M; Spielman, I B

    2017-03-07

    We observed and controlled the Brownian motion of solitons. We launched solitonic excitations in highly elongated [Formula: see text] Bose-Einstein condensates (BECs) and showed that a dilute background of impurity atoms in a different internal state dramatically affects the soliton. With no impurities and in one dimension (1D), these solitons would have an infinite lifetime, a consequence of integrability. In our experiment, the added impurities scatter off the much larger soliton, contributing to its Brownian motion and decreasing its lifetime. We describe the soliton's diffusive behavior using a quasi-1D scattering theory of impurity atoms interacting with a soliton, giving diffusion coefficients consistent with experiment.

  12. Nonlinear beam splitter in Bose-Einstein-condensate interferometers

    SciTech Connect

    Pezze, L.; Smerzi, A.; Berman, G. P.; Bishop, A. R.; Collins, L. A.

    2006-09-15

    A beam splitter is an important component of an atomic/optical Mach-Zehnder interferometer. Here we study a Bose-Einstein condensate beam splitter, realized with a double well potential of tunable height. We analyze how the sensitivity of a Mach-Zehnder interferometer is degraded by the nonlinear particle-particle interaction during the splitting dynamics. We distinguish three regimes, Rabi, Josephson and Fock, and associate to them a different scaling of the phase sensitivity with the total number of particles.

  13. Coherent ratchets in driven Bose-Einstein condensates.

    PubMed

    Creffield, C E; Sols, F

    2009-11-13

    We study the response of a Bose-Einstein condensate to an unbiased periodic driving potential. By controlling the space and time symmetries of the driving we show how a directed current can be induced, producing a coherent quantum ratchet. Weak driving induces a regular behavior, and space and time symmetries must both be broken to produce a current. For strong driving, the behavior becomes chaotic and the resulting effective irreversibility means that it is unnecessary to explicitly break time symmetry. Spatial asymmetry alone is then sufficient to produce the ratchet effect, even in the absence of interactions, and although the system remains completely coherent.

  14. Hidden vorticity in binary Bose-Einstein condensates

    SciTech Connect

    Brtka, Marijana; Gammal, Arnaldo; Malomed, Boris A.

    2010-11-15

    We consider a binary Bose-Einstein condensate (BEC) described by a system of two-dimensional (2D) Gross-Pitaevskii equations with the harmonic-oscillator trapping potential. The intraspecies interactions are attractive, while the interaction between the species may have either sign. The same model applies to the copropagation of bimodal beams in photonic-crystal fibers. We consider a family of trapped hidden-vorticity (HV) modes in the form of bound states of two components with opposite vorticities S{sub 1,2}={+-}1, the total angular momentum being zero. A challenging problem is the stability of the HV modes. By means of a linear-stability analysis and direct simulations, stability domains are identified in a relevant parameter plane. In direct simulations, stable HV modes feature robustness against large perturbations, while unstable ones split into fragments whose number is identical to the azimuthal index of the fastest growing perturbation eigenmode. Conditions allowing for the creation of the HV modes in the experiment are discussed too. For comparison, a similar but simpler problem is studied in an analytical form, viz., the modulational instability of an HV state in a one-dimensional (1D) system with periodic boundary conditions (this system models a counterflow in a binary BEC mixture loaded into a toroidal trap or a bimodal optical beam coupled into a cylindrical shell). We demonstrate that the stabilization of the 1D HV modes is impossible, which stresses the significance of the stabilization of the HV modes in the 2D setting.

  15. Hydrodynamics of vortices and solitons in a dipolar Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Sabari, S.; Dey, Bishwajyoti

    2017-05-01

    By solving the two-dimensional, nonlocal Gross-Pitaevskii equation numerically, we study the hydrodynamics of quantized vortices in a dipolar Bose-Einstein condensate excited by an oscillating potential. We calculate the critical velocity for the vortex nucleation in the presence and absence of dipole-dipole interaction. Above a critical velocity, the oscillating potential nucleates the vortex pairs, whose impulses alternatively change their direction synchronously with the oscillation of the Gaussian potential. We study the dynamics of the vortices and also the formation of the dark solitons which have not been previously reported in a dipolar Bose-Einstein condensate.

  16. Pair-correlation function of a metastable helium Bose-Einstein condensate

    SciTech Connect

    Zin, Pawel; Trippenbach, Marek; Gajda, Mariusz

    2004-02-01

    The pair-correlation function is one of the basic quantities to characterize the coherence properties of a Bose-Einstein condensate. We calculate this function in the experimentally important case of a zero temperature Bose-Einstein condensate in a metastable triplet helium state using the variational method with a pair-excitation ansatz. We compare our result with a pair-correlation function obtained for the hard-sphere potential with the same scattering length. Both functions are practically indistinguishable for distances greater than the scattering length. At smaller distances, due to interatomic interactions, the helium condensate shows strong correlations.

  17. Bose-Einstein condensation of photons in an optical microcavity.

    PubMed

    Klaers, Jan; Schmitt, Julian; Vewinger, Frank; Weitz, Martin

    2010-11-25

    Bose-Einstein condensation (BEC)-the macroscopic ground-state accumulation of particles with integer spin (bosons) at low temperature and high density-has been observed in several physical systems, including cold atomic gases and solid-state quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition. In such systems photons have a vanishing chemical potential, meaning that their number is not conserved when the temperature of the photon gas is varied; at low temperatures, photons disappear in the cavity walls instead of occupying the cavity ground state. Theoretical works have considered thermalization processes that conserve photon number (a prerequisite for BEC), involving Compton scattering with a gas of thermal electrons or photon-photon scattering in a nonlinear resonator configuration. Number-conserving thermalization was experimentally observed for a two-dimensional photon gas in a dye-filled optical microcavity, which acts as a 'white-wall' box. Here we report the observation of a Bose-Einstein condensate of photons in this system. The cavity mirrors provide both a confining potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped, massive bosons. The photons thermalize to the temperature of the dye solution (room temperature) by multiple scattering with the dye molecules. Upon increasing the photon density, we observe the following BEC signatures: the photon energies have a Bose-Einstein distribution with a massively populated ground-state mode on top of a broad thermal wing; the phase transition occurs at the expected photon density and exhibits the predicted dependence on cavity geometry; and the ground-state mode emerges even for a spatially displaced pump spot. The prospects of the observed effects include studies of extremely weakly interacting low-dimensional Bose gases and

  18. Collapse dynamics of a {sup 176}Yb-{sup 174}Yb Bose-Einstein condensate

    SciTech Connect

    Chaudhary, G. K.; Ramakumar, R.

    2010-06-15

    In this paper, we present a theoretical study of a two-component Bose-Einstein condensate composed of ytterbium (Yb) isotopes in a three-dimensional anisotropic harmonic potential. The condensate consists of a mixture of {sup 176}Yb atoms which have a negative s-wave scattering length and {sup 174}Yb atoms having a positive s-wave scattering length. We study the ground-state as well as dynamic properties of this two-component condensate. Due to the attractive interactions between {sup 176}Yb atoms, the condensate of {sup 176}Yb undergoes a collapse when the particle number exceeds a critical value. The critical number and the collapse dynamics are modified due to the presence of {sup 174}Yb atoms. We use coupled two-component Gross-Pitaevskii equations to study the collapse dynamics. The theoretical results obtained are in reasonable agreement with the experimental results of Fukuhara et al. [Phys. Rev. A 79, 021601(R) (2009)].

  19. Bose-Einstein condensation in microgravity.

    PubMed

    van Zoest, T; Gaaloul, N; Singh, Y; Ahlers, H; Herr, W; Seidel, S T; Ertmer, W; Rasel, E; Eckart, M; Kajari, E; Arnold, S; Nandi, G; Schleich, W P; Walser, R; Vogel, A; Sengstock, K; Bongs, K; Lewoczko-Adamczyk, W; Schiemangk, M; Schuldt, T; Peters, A; Könemann, T; Müntinga, H; Lämmerzahl, C; Dittus, H; Steinmetz, T; Hänsch, T W; Reichel, J

    2010-06-18

    Albert Einstein's insight that it is impossible to distinguish a local experiment in a "freely falling elevator" from one in free space led to the development of the theory of general relativity. The wave nature of matter manifests itself in a striking way in Bose-Einstein condensates, where millions of atoms lose their identity and can be described by a single macroscopic wave function. We combine these two topics and report the preparation and observation of a Bose-Einstein condensate during free fall in a 146-meter-tall evacuated drop tower. During the expansion over 1 second, the atoms form a giant coherent matter wave that is delocalized on a millimeter scale, which represents a promising source for matter-wave interferometry to test the universality of free fall with quantum matter.

  20. Bose-Einstein Condensation of Sr84

    NASA Astrophysics Data System (ADS)

    de Escobar, Y. N. Martinez; Mickelson, P. G.; Yan, M.; Desalvo, B. J.; Nagel, S. B.; Killian, T. C.

    2009-11-01

    We report Bose-Einstein condensation of Sr84 in an optical dipole trap. Efficient laser cooling on the narrow intercombination line and an ideal s-wave scattering length allow the creation of large condensates (N0˜3×105) even though the natural abundance of this isotope is only 0.6%. Condensation is heralded by the emergence of a low-velocity component in time-of-flight images.

  1. Schrodinger Leopards in Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.; Dounas-Frazer, Dimitri R.

    2008-03-01

    We present the complex quantum dynamics of vortices in Bose-Einstein condensates in a double well via exact diagonalization of a discretized Hamiltonian. When the barrier is high, vortices evolve into macroscopic superposition (NOON) states of a vortex in either well -- a Schrodinger cat with spots. Such Schrodinger leopard states are more robust than previously proposed NOON states, which only use two single particle modes of the double well potential.

  2. Mechanocaloric and thermomechanical effects in Bose-Einstein-condensed systems

    SciTech Connect

    Marques, G.C.; Bagnato, V.S.; Muniz, S.R.; Spehler, D.

    2004-05-01

    In this paper we extend previous hydrodynamic equations, governing the motion of Bose-Einstein-condensed fluids, to include temperature effects. This allows us to analyze some differences between a normal fluid and a Bose-Einstein-condensed one. We show that, in close analogy with superfluid {sup 4}He, a Bose-Einstein-condensed fluid exhibits the mechanocaloric and thermomechanical effects. In our approach we can explain both effects without using the hypothesis that the Bose-Einstein-condensed fluid has zero entropy. Such ideas could be investigated in existing experiments.

  3. Bose-Einstein condensation in dilute atomic gases

    NASA Astrophysics Data System (ADS)

    Arlt, J.; Bongs, K.; Sengstock, K.; Ertmer, W.

    2002-02-01

    Bose-Einstein condensation is one of the most curious and fascinating phenomena in physics. It lies at the heart of such intriguing processes as superfluidity and superconductivity. However, in most cases, only a small part of the sample is Bose-condensed and strong interactions are present. A weakly interacting, pure Bose-Einstein condensate (BEC) has therefore been called the "holy grail of atomic physics". In 1995 this grail was found by producing almost pure BECs in dilute atomic gases. We review the experimental development that led to the realization of BEC in these systems and explain how BECs are now routinely produced in about 25 laboratories worldwide. The tremendous experimental progress of the past few years is outlined and a number of recent experiments show the current status of the field. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-001-0277-8.

  4. Cavity QED with a Bose-Einstein condensate.

    PubMed

    Brennecke, Ferdinand; Donner, Tobias; Ritter, Stephan; Bourdel, Thomas; Köhl, Michael; Esslinger, Tilman

    2007-11-08

    Cavity quantum electrodynamics (cavity QED) describes the coherent interaction between matter and an electromagnetic field confined within a resonator structure, and is providing a useful platform for developing concepts in quantum information processing. By using high-quality resonators, a strong coupling regime can be reached experimentally in which atoms coherently exchange a photon with a single light-field mode many times before dissipation sets in. This has led to fundamental studies with both microwave and optical resonators. To meet the challenges posed by quantum state engineering and quantum information processing, recent experiments have focused on laser cooling and trapping of atoms inside an optical cavity. However, the tremendous degree of control over atomic gases achieved with Bose-Einstein condensation has so far not been used for cavity QED. Here we achieve the strong coupling of a Bose-Einstein condensate to the quantized field of an ultrahigh-finesse optical cavity and present a measurement of its eigenenergy spectrum. This is a conceptually new regime of cavity QED, in which all atoms occupy a single mode of a matter-wave field and couple identically to the light field, sharing a single excitation. This opens possibilities ranging from quantum communication to a wealth of new phenomena that can be expected in the many-body physics of quantum gases with cavity-mediated interactions.

  5. Bose-Einstein condensation and strong-correlation behavior of phonons in ion traps.

    PubMed

    Porras, D; Cirac, J I

    2004-12-31

    We show that the dynamics of phonons in a set of trapped ions interacting with lasers is described by a Bose-Hubbard model whose parameters can be externally adjusted. We investigate the possibility of observing several quantum many-body phenomena, including Bose-Einstein condensation as well as a superfluid-Mott insulator quantum phase transition.

  6. Entanglement in Bose-Einstein Condensates with One-Body Losses

    NASA Astrophysics Data System (ADS)

    Li, Song-Song

    2017-02-01

    We investigate quantum entanglement in two mutually non-interacting and spatially non-overlapping Bose-Einstein condensates in two harmonic potentials with one-body losses. One-body losses play an important role in the dynamical process of generating quantum entanglement. The stronger one-body losses induce more entanglement and maintain in a longer time interval.

  7. Comparison between the numerical solutions and the Thomas-Fermi approximation for atomic-molecular Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Santos, Leonardo S. F.; Pires, Marcelo O. C.; Giugno, Davi

    2015-03-01

    We study the stationary solution of an atomic Bose-Einstein condensate coupled coherently to a molecular condensate with both repulsive and attractive interspecies interactions confined in an isotropic harmonic trap. We use the Thomas-Fermi approximation and find four kinds of analytical solution for the cases. These analytical solutions are adopted as trial function for the diffusive numerical solution of the Gross-Pitaevskii equations. For the repulsive interspecies interaction, the case in which the atomic and molecular wavefunctions are out-phase, the densities have similar profiles for both methods, however, the case where the wavefunctions are in-phase, there are considerable difference between the density profiles. For the attractive interspecies interaction, there are two cases in the Thomas-Fermi approximation where the wavefunctions are in-phase. One of them has numerical solution that agree with the approximation and the other does not have corresponding numerical solution.

  8. Knot Solitons in Spinor Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Hall, David; Ray, Michael; Tiurev, Konstantin; Ruokokoski, Emmi; Gheorghe, Andrei Horia; Möttönen, Mikko

    2016-05-01

    Knots are familiar entities that appear at a captivating nexus of art, technology, mathematics and science. Following a lengthy period of theoretical investigation and development, they have recently attracted great experimental interest in classical contexts ranging from knotted DNA and nanostructures to vortex knots in fluids. We demonstrate here the controlled creation and detection of knot solitons in the quantum-mechanical order parameter of a spinor Bose-Einstein condensate. Images of the superfluid reveal the circular shape of the soliton core and its associated linked rings. Our observations of the knot soliton establish an experimental foundation for future studies of their stability, dynamics and applications within quantum systems. Supported in part by NSF Grant PHY-1205822.

  9. Dynamics of dissipative Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Caspar, S.; Hebenstreit, F.; Mesterházy, D.; Wiese, U.-J.

    2016-02-01

    We resolve the real-time dynamics of a purely dissipative s =1 /2 quantum spin or, equivalently, hard-core boson model on a hypercubic d -dimensional lattice. The considered quantum dissipative process drives the system to a totally symmetric macroscopic superposition in each of the S3 sectors. Different characteristic time scales are identified for the dynamics and we determine their finite-size scaling. We introduce the concept of cumulative entanglement distribution to quantify multiparticle entanglement and show that the considered protocol serves as an efficient method to prepare a macroscopically entangled Bose-Einstein condensate.

  10. Internal Josephson effects in spinor dipolar Bose-Einstein condensates

    SciTech Connect

    Yasunaga, Masashi; Tsubota, Makoto

    2010-02-15

    We theoretically study the internal Josephson effect, which is driven by spin-exchange interactions and magnetic dipole-dipole interactions, in a three-level system for spin-1 Bose-Einstein condensates, obtaining novel spin dynamics. We introduce single spatial mode approximations into the Gross-Pitaevskii equations and derive the Josephson-type equations, which are analogous to tunneling currents through three junctions between three superconductors. From an analogy with two interacting nonrigid pendulums, we identify unique varied oscillational modes, called the 0-{pi}, 0-running, running-running, 2n{pi} and running-2{pi}, single nonrigid pendulum, and two rigid pendulums phase modes. These Josephson modes in the three states are expected to be found in real atomic Bose gas systems.

  11. Bose-Einstein condensation of positronium in silica pores

    NASA Astrophysics Data System (ADS)

    Morandi, O.; Hervieux, P.-A.; Manfredi, G.

    2014-03-01

    We investigate the possibility to produce a Bose-Einstein condensate made of positronium atoms in a porous silica material containing isolated nanometric cavities. The evolution equation of a weakly interacting positronium system is presented. The model includes the interactions among the atoms in the condensate, the surrounding gas of noncondensed atoms, and the pore surface. The final system is expressed by the Boltzmann evolution equation for noncondensed particles coupled with the Gross-Pitaevskii equation for the condensate. In particular, we focus on the estimation of the time necessary to form a condensate containing a macroscopic fraction of the positronium atoms initially injected in the material. The numerical simulations reveal that the condensation process is compatible with the lifetime of ortho-positronium.

  12. Quantum Rabi model in a superfluid Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Felicetti, S.; Romero, G.; Solano, E.; Sabín, C.

    2017-09-01

    We propose a quantum simulation of the quantum Rabi model in an atomic quantum dot, which is a single atom in a tight optical trap coupled to the quasiparticle modes of a superfluid Bose-Einstein condensate. This widely tunable setup allows us to simulate the ultrastrong coupling regime of light-matter interaction in a system which enjoys an amenable characteristic time scale, paving the way for an experimental analysis of the transition between the Jaynes-Cummings and the quantum Rabi dynamics using cold-atom systems. Our scheme can be naturally extended to simulate multiqubit quantum Rabi models. In particular, we discuss the appearance of effective two-qubit interactions due to phononic exchange, among other features.

  13. Vortex scattering by impurities in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Griffin, A.; Stagg, G. W.; Proukakis, N. P.; Barenghi, C. F.

    2017-06-01

    Understanding quantum dynamics in a two-dimensional Bose-Einstein condensate relies on understanding how vortices interact with each other microscopically and with local imperfections of the potential which confines the condensate. Within a system consisting of many vortices, the trajectory of a vortex-antivortex pair is often scattered by a third vortex, an effect previously characterised. However, the natural question remains as to how much of this effect is due to the velocity induced by this third vortex and how much is due to the density inhomogeneity which it introduces. In this work, we describe the various qualitative scenarios which occur when a vortex-antivortex pair interacts with a smooth density impurity whose profile is identical to that of a vortex but lacks the circulation around it.

  14. Predicted signatures of rotating Bose-Einstein Condensates

    SciTech Connect

    Butts, D.A.; Rokhsar, D.S.

    1999-01-01

    Superfluids are distinguished from normal fluidsby theirpeculiar response1 to rotation: circulating flow in superfuid helium2,3,astrongly coupled Bose liquid, can appear only as quantized vortices4-6.The newly created Bose-Einstein condensates7,9--clouds of millions ofultracold, weakly interacting alkali-metal atoms that occupy a singlequantum state Doffer the possibility of investigating superuidity in theweak-coupling regime. An outstanding question is whether Bose-Einsteincondensates exhibit a mesoscopic quantum analogue of the macroscopicvortices in superfluids, and what its experimental signature would be.Here we report calculations of the low-energy states of a rotating,weakly interacting Bose gas. We find a succession of transitions betweenstab reement with observations5 of rotating super-fluid helium, astrong-coupling superfuid. Counterintuitively, the angular momentum perparticle is not quantized. Some angular momenta are forbidden,corresponding to asymmetrical unstablestates that provide a physicalmechanism for the entry of vorticity into the condensate.

  15. Dissipative transport of a Bose-Einstein condensate

    SciTech Connect

    Dries, D.; Pollack, S. E.; Hitchcock, J. M.; Hulet, R. G.

    2010-09-15

    We investigate the effects of impurities, either correlated disorder or a single Gaussian defect, on the collective dipole motion of a Bose-Einstein condensate of {sup 7}Li in an optical trap. We find that this motion is damped at a rate dependent on the impurity strength, condensate center-of-mass velocity, and interatomic interactions. Damping in the Thomas-Fermi regime depends universally on the disordered potential strength scaled to the condensate chemical potential and the condensate velocity scaled to the speed of sound. The damping rate is comparatively small in the weakly interacting regime, and, in this case, is accompanied by strong condensate fragmentation. In situ and time-of-flight images of the atomic cloud provide evidence that this fragmentation is driven by dark soliton formation.

  16. Atomic quantum corrals for Bose-Einstein condensates

    SciTech Connect

    Xiong Hongwei; Wu Biao

    2010-11-15

    We consider the dynamics of Bose-Einstein condensates in a corral-like potential. Compared to the electronic quantum corrals, the atomic quantum corrals have the advantages of allowing direct and convenient observation of the wave dynamics, together with adjustable interaction strength. Our numerical study shows that these advantages not only allow exploration of the rich dynamical structures in the density distribution but also make the corrals useful in many other aspects. In particular, the corrals for atoms can be arranged into a stadium shape for the experimental visualization of quantum chaos, which has been elusive with electronic quantum corrals. The density correlation is used to describe quantitatively the dynamical quantum chaos. Furthermore, we find that the interatomic interaction can greatly enhance the dynamical quantum chaos, for example, inducing a chaotic behavior even in circle-shaped corrals.

  17. Landau criterion for an anisotropic Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Yu, Zeng-Qiang

    2017-03-01

    In this work we discuss the Landau criterion for anisotropic superfluidity. To this end we consider a pointlike impurity moving in a uniform Bose-Einstein condensate with either interparticle dipole-dipole interaction or Raman-induced spin-orbit coupling. In both cases we find that the Landau critical velocity vc is generally smaller than the sound velocity in the moving direction. Beyond vc, the energy dissipation rate is explicitly calculated via a perturbation approach. In the plane-wave phase of a spin-orbit-coupled Bose gas, the dissipationless motion is suppressed by the Raman coupling even in the direction orthogonal to the recoil momentum. Our predictions can be tested in the experiments with ultracold atoms.

  18. Dynamics of nonautonomous rogue waves in Bose-Einstein condensate

    SciTech Connect

    Zhao, Li-Chen

    2013-02-15

    We study rogue waves of Bose-Einstein condensate (BEC) analytically in a time-dependent harmonic trap with a complex potential. Properties of the nonautonomous rogue waves are investigated analytically. It is reported that there are possibilities to 'catch' rogue waves through manipulating nonlinear interaction properly. The results provide many possibilities to manipulate rogue waves experimentally in a BEC system. - Highlights: Black-Right-Pointing-Pointer One more generalized rogue wave solutions are presented. Black-Right-Pointing-Pointer Present one possible way to catch a rouge wave. Black-Right-Pointing-Pointer Properties of rogue waves are investigated analytically for the first time. Black-Right-Pointing-Pointer Provide many possibilities to manipulate rogue waves in BEC.

  19. Optical computing with soliton trains in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Pinsker, Florian

    2015-12-01

    Optical computing devices can be implemented based on controlled generation of soliton trains in single and multicomponent Bose-Einstein condensates (BEC). Our concepts utilize the phenomenon that the frequency of soliton trains in BEC can be governed by changing interactions within the atom cloud [F. Pinsker, N. G. Berloff and V. M. Pérez-García, Phys. Rev. A87, 053624 (2013), arXiv:1305.4097]. We use this property to store numbers in terms of those frequencies for a short time until observation. The properties of soliton trains can be changed in an intended way by other components of BEC occupying comparable states or via phase engineering. We elucidate, in which sense, such an additional degree of freedom can be regarded as a tool for controlled manipulation of data. Finally, the outcome of any manipulation made is read out by observing the signature within the density profile.

  20. Matter-waves in Bose-Einstein condensates with spin-orbit and Rabi couplings

    NASA Astrophysics Data System (ADS)

    Chiquillo, Emerson

    2015-11-01

    We investigate the one-dimensional (1D) and two-dimensional (2D) reduction of a quantum field theory starting from the three-dimensional (3D) many-body Hamiltonian of interacting bosons with spin-orbit (SO) and Rabi couplings. We obtain the effective time-dependent 1D and 2D nonpolynomial Heisenberg equations for both the repulsive and attractive signs of the inter-atomic interaction. Our findings show that in the case in which the many-body state coincides with the Glauber coherent state, the 1D and 2D Heisenberg equations become 1D and 2D nonpolynomial Schrödinger equations (NPSEs). These models were derived in a mean-field approximation from 3D Gross-Pitaevskii equation (GPE), describing a Bose-Einstein condensate (BEC) with SO and Rabi couplings. In the present work self-repulsive and self-attractive localized solutions of the 1D NPSE and the 1D GPE are obtained in a numerical form. The combined action of SO and Rabi couplings produces conspicuous sidelobes on the density profile, for both signs of the interaction. In the case of the attractive nonlinearity, an essential result is the possibility of getting an unstable condensate by the increasing of SO coupling.

  1. Solitonic vortices in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Tylutki, M.; Donadello, S.; Serafini, S.; Pitaevskii, L. P.; Dalfovo, F.; Lamporesi, G.; Ferrari, G.

    2015-04-01

    We analyse, theoretically and experimentally, the nature of solitonic vortices (SV) in an elongated Bose-Einstein condensate. In the experiment, such defects are created via the Kibble-Zurek mechanism, when the temperature of a gas of sodium atoms is quenched across the BEC transition, and are imaged after a free expansion of the condensate. By using the Gross-Pitaevskii equation, we calculate the in-trap density and phase distributions characterizing a SV in the crossover from an elongated quasi-1D to a bulk 3D regime. The simulations show that the free expansion strongly amplifies the key features of a SV and produces a remarkable twist of the solitonic plane due to the quantized vorticity associated with the defect. Good agreement is found between simulations and experiments.

  2. Nonlinear interferometry with Bose-Einstein condensates

    SciTech Connect

    Tacla, Alexandre B.; Boixo, Sergio; Datta, Animesh; Shaji, Anil; Caves, Carlton M.

    2010-11-15

    We analyze a proposed experiment [Boixo et al., Phys. Rev. Lett. 101, 040403 (2008)] for achieving sensitivity scaling better than 1/N in a nonlinear Ramsey interferometer that uses a two-mode Bose-Einstein condensate (BEC) of N atoms. We present numerical simulations that confirm the analytical predictions for the effect of the spreading of the BEC ground-state wave function on the ideal 1/N{sup 3/2} scaling. Numerical integration of the coupled, time-dependent, two-mode Gross-Pitaevskii equations allows us to study the several simplifying assumptions made in the initial analytic study of the proposal and to explore when they can be justified. In particular, we find that the two modes share the same spatial wave function for a length of time that is sufficient to run the metrology scheme.

  3. Solitons in Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.

    2003-05-01

    The stationary form, dynamical properties, and experimental criteria for creation of matter-wave bright and dark solitons, both singly and in trains, are studied numerically and analytically in the context of Bose-Einstein condensates [1]. The full set of stationary solutions in closed analytic form to the mean field model in the quasi-one-dimensional regime, which is a nonlinear Schrodinger equation equally relevant in nonlinear optics, is developed under periodic and box boundary conditions [2]. These solutions are extended numerically into the two and three dimensional regimes, where it is shown that dark solitons can be used to create vortex-anti-vortex pairs under realistic conditions. Specific experimental prescriptions for creating viable dark and bright solitons in the quasi-one-dimensional regime are provided. These analytic methods are then extended to treat the nonlinear Schrodinger equation with a generalized lattice potential, which models a Bose-Einstein condensate trapped in the potential generated by a standing light wave. A novel solution family is developed and stability criterion are presented. Experiments which successfully carried out these ideas are briefly discussed [3]. [1] Dissertation research completed at the University of Washington Physics Department under the advisorship of Prof. William P. Reinhardt. [2] L. D. Carr, C. W. Clark, and W. P. Reinhardt, Phys. Rev. A v. 62 p. 063610-1--10 and Phys. Rev. A v.62, p.063611-1--10 (2000). [3] L. Khaykovich, F. Schreck, T. Bourdel, J. Cubizolles, G. Ferrari, L. D. Carr, Y. Castin, and C. Salomon, Science v. 296, p.1290--1293 (2002).

  4. Modulation instability in quasi-two-dimensional spin-orbit coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Bhuvaneswari, S.; Nithyanandan, K.; Muruganandam, P.; Porsezian, K.

    2016-12-01

    We theoretically investigate the dynamics of modulation instability (MI) in two-dimensional spin-orbit coupled Bose-Einstein condensates (BECs) with Rabi coupling. The analysis is performed for equal densities of pseudo-spin components. Different combination of the signs of intra- and intercomponent interaction strengths are considered, with a particular emphasis on repulsive interactions. We observe that the unstable modulation builds from originally miscible condensates, depending on the combination of the signs of the intra- and intercomponent interaction strengths. The repulsive intra- and intercomponent interactions admit instability and the MI immiscibility condition is no longer significant. The influence of interaction parameters such as spin-orbit and Rabi coupling on MI are also investigated. The spin-orbit coupling (SOC) inevitably contributes to instability regardless of the nature of the interaction. In the case of attractive interaction, SOC manifests in enhancing the MI. Thus, a comprehensive study of MI in two-dimensional spin-orbit coupled BECs of pseudo-spin components is presented.

  5. Exactly solvable models for multiatomic molecular Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Santos, G.

    2011-08-01

    I introduce two families of exactly solvable models for multiatomic hetero-nuclear and homo-nuclear molecular Bose-Einstein condensates through the algebraic Bethe ansatz method. The conserved quantities of the respective models are also shown.

  6. Two-fluid model of a Bose-Einstein condensate in the cavity optomechanical regime

    NASA Astrophysics Data System (ADS)

    Goldbaum, Dan; Zhang, Keye; Meystre, Pierre

    2010-03-01

    We analyze an atomic Bose-Einstein condensate trapped in a high-Q optical cavity driven by a feeble optical field. The dynamics of the resulting collective density excitation of the condensate are formally analogous to the central model system of cavity optomechanics: a radiation pressure driven mechanical oscillator [Brennecke et al., Science 322, 235 (2008)]. However, although BEC-based optomechanical systems have several desirable properties, one must also take into account the effect of atom-atom interactions. We treat these interactions via a two-fluid model that retains the intuitive appeal of the non-interacting two-mode description. We find that the Bogoliubov excitation spectrum of this system comprises a gapped upper branch and a lower branch that can include an unstable excitation mode. [4pt] D. S. Goldbaum, K. Zhang and P. Meystre, Two-fluid model of a Bose-Einstein condensate in the cavity optomechanical regime, arXiv:0911.3234.

  7. Nonlinear patterns in Bose-Einstein condensates in dissipative optical lattices

    SciTech Connect

    Bludov, Yu. V.; Konotop, V. V.

    2010-01-15

    It is shown that the one-dimensional nonlinear Schroedinger equation with a dissipative periodic potential, nonlinear losses, and a linear pump allow for the existence of stable nonlinear Bloch states which are attractors. The model describes a Bose-Einstein condensate with inelastic two- and three-body interactions loaded in an optical lattice with losses due to inelastic interactions of the atoms with photons.

  8. Numerical study of the coupled time-dependent Gross-Pitaevskii equation: application to Bose-Einstein condensation.

    PubMed

    Adhikari, S K

    2001-05-01

    We present a numerical study of the coupled time-dependent Gross-Pitaevskii equation, which describes the Bose-Einstein condensate of several types of trapped bosons at ultralow temperature with both attractive and repulsive interatomic interactions. The same approach is used to study both stationary and time-evolution problems. We consider up to four types of atoms in the study of stationary problems. We consider the time-evolution problems where the frequencies of the traps or the atomic scattering lengths are suddenly changed in a stable preformed condensate. We also study the effect of periodically varying these frequencies or scattering lengths on a preformed condensate. These changes introduce oscillations in the condensate, which are studied in detail. Good convergence is obtained in all cases studied.

  9. Observation of Vortex Pinning in Bose-Einstein Condensates

    SciTech Connect

    Tung, S.; Schweikhard, V.; Cornell, E. A.

    2006-12-15

    We report the observation of vortex pinning in rotating gaseous Bose-Einstein condensates. Vortices are pinned to columnar pinning sites created by a corotating optical lattice superimposed on the rotating Bose-Einstein condensates. We study the effects of two types of optical lattice: triangular and square. In both geometries we see an orientation locking between the vortex and the optical lattices. At sufficient intensity the square optical lattice induces a structural crossover in the vortex lattice.

  10. Bragg spectroscopy with an accelerating Bose-Einstein condensate

    SciTech Connect

    Geursen, R.; Thomas, N.R.; Wilson, A.C.

    2003-10-01

    We present the results of Bragg spectroscopy performed on an accelerating Bose-Einstein condensate. The Bose-Einstein condensate undergoes circular micromotion in a magnetic time-averaged orbiting potential trap and the effect of this motion on the Bragg spectrum is analyzed. A simple frequency modulation model is used to interpret the observed complex structure, and broadening effects are considered using numerical solutions to the Gross-Pitaevskii equation.

  11. Far from equilibrium dynamics of Bose-Einstein condensation for axion dark matter

    NASA Astrophysics Data System (ADS)

    Berges, Jürgen; Jaeckel, Joerg

    2015-01-01

    Axions and similar very weakly interacting particles are increasingly compelling candidates for the cold dark matter of the Universe. Having very low mass and being produced nonthermally in the early universe, axions feature extremely high occupation numbers. It has been suggested that this leads to the formation of a Bose-Einstein condensate with potentially significant impact on observation and direct detection experiments. In this paper we aim to clarify that if Bose-Einstein condensation occurs for light and very weakly interacting dark matter particles, it does not happen in thermal equilibrium but is described by a far from equilibrium state. In particular we point out that the dynamics is characterized by two very different time scales, such that condensation occurs on a much shorter time scale than full thermalization.

  12. Bose-Einstein condensation of the classical axion field in cosmology?

    SciTech Connect

    Davidson, Sacha; Elmer, Martin E-mail: m.elmer@ipnl.in2p3.fr

    2013-12-01

    The axion is a motivated cold dark matter candidate, which it would be interesting to distinguish from weakly interacting massive particles. Sikivie has suggested that axions could behave differently during non-linear galaxy evolution, if they form a Bose-Einstein condensate, and argues that ''gravitational thermalisation'' drives them to a Bose-Einstein condensate during the radiation dominated era. Using classical equations of motion during linear structure formation, we explore whether the gravitational interactions of axions can generate enough entropy. At linear order in G{sub N}, we interpret that the principle activities of gravity are to expand the Universe and grow density fluctuations. To quantify the rate of entropy creation we use the anisotropic stress to estimate a short dissipation scale for axions which does not confirm previous estimates of their gravitational thermalisation rate.

  13. Ferroelectricity by Bose-Einstein condensation in a quantum magnet

    NASA Astrophysics Data System (ADS)

    Kimura, S.; Kakihata, K.; Sawada, Y.; Watanabe, K.; Matsumoto, M.; Hagiwara, M.; Tanaka, H.

    2016-09-01

    The Bose-Einstein condensation is a fascinating phenomenon, which results from quantum statistics for identical particles with an integer spin. Surprising properties, such as superfluidity, vortex quantization or Josephson effect, appear owing to the macroscopic quantum coherence, which spontaneously develops in Bose-Einstein condensates. Realization of Bose-Einstein condensation is not restricted in fluids like liquid helium, a superconducting phase of paired electrons in a metal and laser-cooled dilute alkali atoms. Bosonic quasi-particles like exciton-polariton and magnon in solids-state systems can also undergo Bose-Einstein condensation in certain conditions. Here, we report that the quantum coherence in Bose-Einstein condensate of the magnon quasi particles yields spontaneous electric polarization in the quantum magnet TlCuCl3, leading to remarkable magnetoelectric effect. Very soft ferroelectricity is realized as a consequence of the O(2) symmetry breaking by magnon Bose-Einstein condensation. The finding of this ferroelectricity will open a new window to explore multi-functionality of quantum magnets.

  14. Ferroelectricity by Bose-Einstein condensation in a quantum magnet.

    PubMed

    Kimura, S; Kakihata, K; Sawada, Y; Watanabe, K; Matsumoto, M; Hagiwara, M; Tanaka, H

    2016-09-26

    The Bose-Einstein condensation is a fascinating phenomenon, which results from quantum statistics for identical particles with an integer spin. Surprising properties, such as superfluidity, vortex quantization or Josephson effect, appear owing to the macroscopic quantum coherence, which spontaneously develops in Bose-Einstein condensates. Realization of Bose-Einstein condensation is not restricted in fluids like liquid helium, a superconducting phase of paired electrons in a metal and laser-cooled dilute alkali atoms. Bosonic quasi-particles like exciton-polariton and magnon in solids-state systems can also undergo Bose-Einstein condensation in certain conditions. Here, we report that the quantum coherence in Bose-Einstein condensate of the magnon quasi particles yields spontaneous electric polarization in the quantum magnet TlCuCl3, leading to remarkable magnetoelectric effect. Very soft ferroelectricity is realized as a consequence of the O(2) symmetry breaking by magnon Bose-Einstein condensation. The finding of this ferroelectricity will open a new window to explore multi-functionality of quantum magnets.

  15. Solvable model of a trapped mixture of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Klaiman, Shachar; Streltsov, Alexej I.; Alon, Ofir E.

    2017-01-01

    A mixture of two kinds of identical bosons held in a harmonic potential and interacting by harmonic particle-particle interactions is discussed. This is an exactly-solvable model of a mixture of two trapped Bose-Einstein condensates which allows us to examine analytically various properties. Generalizing the treatments in Cohen and Lee (1985) and Osadchii and Muraktanov (1991), closed form expressions for the mixture's frequencies and ground-state energy and wave-function, and the lowest-order densities are obtained and analyzed for attractive and repulsive intra-species and inter-species particle-particle interactions. A particular mean-field solution of the corresponding Gross-Pitaevskii theory is also found analytically. This allows us to compare properties of the mixture at the exact, many-body and mean-field levels, both for finite systems and at the limit of an infinite number of particles. We discuss the renormalization of the mixture's frequencies at the mean-field level. Mainly, we hereby prove that the exact ground-state energy per particle and lowest-order intra-species and inter-species densities per particle converge at the infinite-particle limit (when the products of the number of particles times the intra-species and inter-species interaction strengths are held fixed) to the results of the Gross-Pitaevskii theory for the mixture. Finally and on the other end, we use the mixture's and each species' center-of-mass operators to show that the Gross-Pitaevskii theory for mixtures is unable to describe the variance of many-particle operators in the mixture, even in the infinite-particle limit. The variances are computed both in position and momentum space and the respective uncertainty products compared and discussed. The role of the center-of-mass separability and, for generically trapped mixtures, inseparability is elucidated when contrasting the variance at the many-body and mean-field levels in a mixture. Our analytical results show that many

  16. Force on a moving point impurity due to quantum fluctuations in a Bose-Einstein condensate

    SciTech Connect

    Roberts, D. C.

    2006-07-15

    An analytic expression is derived for a force on a weak point impurity arising from the scattering of quantum fluctuations in a slow-moving, weakly interacting, three-dimensional Bose-Einstein condensate at zero temperature. In an infinitely extended geometry, this force is shown to exist at any arbitrarily small flow velocity below Landau's critical velocity. Furthermore, this force is shown to be directly proportional to the flow speed.

  17. Capillary instability in a two-component Bose-Einstein condensate

    SciTech Connect

    Sasaki, Kazuki; Suzuki, Naoya; Saito, Hiroki

    2011-05-15

    Capillary instability and the resulting dynamics in an immiscible two-component Bose-Einstein condensate are investigated using the mean-field and Bogoliubov analyses. A long, cylindrical condensate surrounded by the other component is dynamically unstable against breakup into droplets due to the interfacial tension arising from the quantum pressure and interactions. A heteronuclear system confined in a cigar-shaped trap is proposed for realizing this phenomenon experimentally.

  18. Hall effects in Bose-Einstein condensates in a rotating optical lattice

    SciTech Connect

    Bhat, Rajiv; Kraemer, M.; Cooper, J.; Holland, M. J.

    2007-10-15

    Using linear response theory, we demonstrate fractional quantum Hall features in a rotating Bose-Einstein condensate in a corotating two-dimensional optical lattice. The corotating lattice and trap potential allow for an effective magnetic field and compensation of the centrifugal potential. Fractional quantum Hall features in the current response are seen for the single-particle system and for a few strongly interacting many-particle systems.

  19. Ferrofluidity in a Two-Component Dipolar Bose-Einstein Condensate

    SciTech Connect

    Saito, Hiroki; Kawaguchi, Yuki; Ueda, Masahito

    2009-06-12

    It is shown that the interface in a two-component Bose-Einstein condensate (BEC) with a dipole-dipole interaction spontaneously develops patterns similar to those formed in a ferrofluid. Hexagonal, labyrinthine, solitonlike structures, and hysteretic behavior are numerically demonstrated. Superflow is found to circulate around the hexagonal pattern at rest, offering evidence of supersolidity. The system sustains persistent current with a vortex line pinned by the hexagonal pattern. These phenomena may be realized using a {sup 52}Cr BEC.

  20. Ferrofluidity in a two-component dipolar Bose-Einstein condensate.

    PubMed

    Saito, Hiroki; Kawaguchi, Yuki; Ueda, Masahito

    2009-06-12

    It is shown that the interface in a two-component Bose-Einstein condensate (BEC) with a dipole-dipole interaction spontaneously develops patterns similar to those formed in a ferrofluid. Hexagonal, labyrinthine, solitonlike structures, and hysteretic behavior are numerically demonstrated. Superflow is found to circulate around the hexagonal pattern at rest, offering evidence of supersolidity. The system sustains persistent current with a vortex line pinned by the hexagonal pattern. These phenomena may be realized using a 52Cr BEC.

  1. Vortex-nucleating Zeeman resonance in axisymmetric rotating Bose-Einstein condensates.

    PubMed

    Reinisch, Gilbert

    2007-09-21

    By use of the Larmor equivalence between uniform rotation and a magnetic field, we consider in the strong-interaction Thomas-Fermi regime the single centered vortex as the first Zeeman-like excited state of the axisymmetric rotating Bose-Einstein condensate. This yields a resonant-drive nucleation mechanism whose threshold is in quite good agreement with ENS, MIT, and JILA experimental results.

  2. Vortex formation and hidden vortices in dipolar Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Subramaniyan, Sabari

    2017-09-01

    We examine vortex formation in dipolar Bose-Einstein condensates (BECs) with rotating double-well (DW) trap potential. For this purpose, we solve a two-dimensional, nonlocal Gross-Pitaevskii equation numerically. We obtain the critical rotation frequency (Ωc) for vortex formation in dipolar BECs for two different species and three different interaction strengths in each case. We also study hidden vortices, which are positioned along the DW potential, for all possible cases.

  3. Amplification of matter rogue waves and breathers in quasi-two-dimensional Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Manikandan, K.; Senthilvelan, M.; Kraenkel, R. A.

    2016-02-01

    We construct rogue wave and breather solutions of a quasi-two-dimensional Gross-Pitaevskii equation with a time-dependent interatomic interaction and external trap. We show that the trapping potential and an arbitrary functional parameter that present in the similarity transformation should satisfy a constraint for the considered equation to be integrable and yield the desired solutions. We consider two different forms of functional parameters and investigate how the density of the rogue wave and breather profiles vary with respect to these functional parameters. We also construct vector localized solutions of a two coupled quasi-two-dimensional Bose-Einstein condensate system. We then investigate how the vector localized density profiles modify in the constant density background with respect to the functional parameters. Our results may help to manipulate matter rogue waves experimentally in the two-dimensional Bose-Einstein condensate systems.

  4. Exploring ground states and excited states of spin-1 Bose-Einstein condensates by continuation methods

    SciTech Connect

    Chen, Jen-Hao; Chern, I-Liang; Wang Weichung

    2011-03-20

    A pseudo-arclength continuation method (PACM) is employed to compute the ground state and excited state solutions of spin-1 Bose-Einstein condensates (BEC). The BEC is governed by the time-independent coupled Gross-Pitaevskii equations (GPE) under the conservations of the mass and magnetization. The coupling constants that characterize the spin-independent and spin-exchange interactions are chosen as the continuation parameters. The continuation curve starts from a ground state or an excited state with very small coupling parameters. The proposed numerical schemes allow us to investigate the effect of the coupling constants and study the bifurcation diagrams of the time-independent coupled GPE. Numerical results on the wave functions and their corresponding energies of spin-1 BEC with repulsive/attractive and ferromagnetic/antiferromagnetic interactions are presented. Furthermore, we reveal that the component separation and population transfer between the different hyperfine states can only occur in excited states due to the spin-exchange interactions.

  5. Exploring matter-wave dynamics with a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Chang, Rockson

    Bose-Einstein condensates of dilute gases provide a rich and versatile platform to study both single-particle and many-body quantum phenomena. This thesis describes several experiments using a Bose-Einstein condensate of Rb-87 as a model system to study novel matter-wave effects that traditionally arise in vastly different systems, yet are difficult to access. We study the scattering of a particle from a repulsive potential barrier in the non-asymptotic regime, for which the collision dynamics are on-going. Using a Bose-Einstein condensate interacting with a sharp repulsive potential, two distinct transient scattering effects are observed: one due to the momentary deceleration of particles atop the barrier, and one due to the abrupt discontinuity in phase written on the wavepacket in position-space, akin to quantum reflection. Both effects lead to a redistribution of momenta, resulting in a rich interference pattern that may be used to reconstruct the single-particle wavefunction. In a second experiment, we study the response of a particle in a periodic potential to an applied force. By abruptly applying an external force to a Bose-Einstein condensate in a one-dimensional optical lattice, we show that the initial response of a particle in a periodic potential is in fact characterized by the bare mass, and only over timescales long compared to that of interband dynamics is the usual effective mass an appropriate description. This breakdown of the effective mass description on fast timescales is difficult to observe in traditional solid state systems due to their large bandgaps and fast timescale of interband dynamics. Both these experiments make use of the condensate's long coherence length, and the ability to shape and modulate the external potential on timescales fast compared to the particle dynamics, allowing for observation of novel matter-wave effects.

  6. Nonlinear enhancement of the fractal structure in the escape dynamics of Bose-Einstein condensates

    SciTech Connect

    Mitchell, Kevin A.; Ilan, Boaz

    2009-10-15

    We consider the escape dynamics of an ensemble of Bose-Einstein-condensed atoms from an optical-dipole trap consisting of two overlapping Gaussian wells. Earlier theoretical studies (based on a model of quantum evolution using ensembles of classical trajectories) predicted that self-similar fractal features could be visible in this system by measuring the escaping flux as a function of time for varying initial conditions. Here, direct numerical quantum simulations show the clear influence of quantum interference on the escape data. Fractal features are still evident in the data, albeit with interference fringes superposed. Furthermore, the nonlinear influence of atom-atom interactions is also considered, in the context of the (2+1)-dimensional Gross-Pitaevskii equation. Of particular note is that an attractive nonlinear interaction enhances the resolution of fractal structures in the escape data. Thus, the interplay between nonlinear focusing and dispersion results in dynamics that resolve the underlying classical fractal more faithfully than the noninteracting quantum (or classical) dynamics.

  7. Nonlinear phenomena in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.

    2008-05-01

    We present a medley of results from the last three years on nonlinear phenomena in BECs [1]. These include exact dynamics of multi-component condensates in optical lattices [2], vortices and ring solitons [3], macroscopic quantum tunneling [4], nonlinear band theory [5], and a pulsed atomic soliton laser [6]. 1. Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment, ed. P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer-Verlag, 2008). 2. R. Mark Bradley, James E. Bernard, and L. D. Carr, e-print arXiv:0711.1896 (2007). 3. G. Herring, L. D. Carr, R. Carretero-Gonzalez, P. G. Kevrekidis, D. J. Frantzeskakis, Phys. Rev. A in press, e-print arXiv:0709.2193 (2007); L. D. Carr and C. W. Clark, Phys. Rev. A v. 74, p.043613 (2006); L. D. Carr and C. W. Clark, Phys. Rev. Lett. v. 97, p.010403 (2006). 4. L. D. Carr, M. J. Holland, and B. A. Malomed, J. Phys. B: At. Mol. Opt. Phys., v.38, p.3217 (2005) 5. B. T. Seaman, L. D. Carr, and M. J. Holland, Phys. Rev. A, v. 71, p.033622 (2005). 6. L. D. Carr and J. Brand, Phys. Rev. A, v.70, p.033607 (2004); L. D. Carr and J. Brand, Phys. Rev. Lett., v.92, p.040401 (2004).

  8. Gravitational dynamics in Bose-Einstein condensates

    SciTech Connect

    Girelli, F.; Liberati, S.; Sindoni, L.

    2008-10-15

    Analogue models for gravity intend to provide a framework where matter and gravity, as well as their intertwined dynamics, emerge from degrees of freedom that have a priori nothing to do with what we call gravity or matter. Bose-Einstein condensates (BEC) are a natural example of an analogue model since one can identify matter propagating on a (pseudo-Riemannian) metric with collective excitations above the condensate of atoms. However, until now, a description of the 'analogue gravitational dynamics' for such model was missing. We show here that in a BEC system with massive quasiparticles, the gravitational dynamics can be encoded in a modified (semiclassical) Poisson equation. In particular, gravity is of extreme short range (characterized by the healing length) and the cosmological constant appears from the noncondensed fraction of atoms in the quasiparticle vacuum. While some of these features make the analogue gravitational dynamics of our BEC system quite different from standard Newtonian gravity, we nonetheless show that it can be used to draw some interesting lessons about 'emergent gravity' scenarios.

  9. Bose-Einstein condensation in solid helium

    NASA Astrophysics Data System (ADS)

    Azuah, Richard; Diallo, Souleymane; Kirichek, Oleg; Taylor, Jon; Glyde, Henry

    2009-03-01

    We report new measurements of the Bose-Einstein condensate fraction in solid helium. The goal is to reveal whether there is BEC associated with the superfluid fractions that have been observed in solid helium [1,2]. The condensate fraction, n0, is obtained from neutron scattering measurements of the momentum distribution, n(k), of the atoms in the solid. We use commercial grade helium (^3He concentration of 0.3 %) where the Tc for superflow is Tc = 200 mK and have measured the n(k) at 3 temperatures, 500 mK, 150 mK and 65 mK. We use a sample cell that has a large surface to volume ratio (S/V) = 40 cm-1 where large superfluid fractions have recently been reported[2]. We use a large sample volume (100 cm^3) and high instrument resolution to improve precision beyond that of previous measurements [3]. No clear sign of BEC has been observed but the data is being analyzed so that specific values of n0 can be reported. [1] E. Kim and M.H.W. Chan. Science, 305:1941 (2004); Nature, 427:225, 2004. [2]A. S. C. Rittner, and J. D. Reppy, Phys. Rev. Lett., 98:175302, 2007. [3] Diallo et al. Phys. Rev Lett. 98, 205301 (2007).

  10. Heuristic field theory of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Stenholm, Stig

    2002-06-01

    This paper reviews the basic ideas of the field theoretic approach to Bose-Einstein condensation. The central concepts are presented in a historical way, the most important results are given and they are justified by heuristic physical ideas instead of detailed derivations. The mathematical level of rigour is low, and the intuitive relations between the concepts and their physical origin is used to justify the various results. I present the original Bose-Einstein conception of bosons condensing into a macroscopically occupied state. The special features deriving from this situation are discussed, and the concept of long-range order is introduced. Historically the concept of broken symmetry has played a central role in the description of Bose condensates. In this approach the system is described by states with broken particle conservation, which justifies the introduction of a physical phase factor. When interactions are present, this acquires its own dynamic behaviour, which gives rise to the low-lying collective excitations of the system. They can be interpreted as collisionless oscillations of the particle density. The condensate acting as a particle reservoir introduces a coupling between these collective excitations and the single-particle ones, which makes the collective excitations dominate the physics of the system. This justifies the hydrodynamic view of a condensed Bose system, which has been central to both the theoretical approaches and the interpretations of experiments on superfluid helium. The results are derived using both algebraic and perturbative methods; some of the tools from formal many-body theory are summarized in the appendix. The treatment approaches most issues from a bulk material point of view, but I also keep the possibility open to apply the results to the topical field of trapped condensates. The equation for the order parameter, the Gross-Pitaevski equation, is presented and discussed, but its detailed applications to trapped alkali

  11. Decay of hydrodynamic modes in dilute Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Gust, Erich; Reichl, Linda

    2015-03-01

    We present the results of Bogoliubov mean field theory applied to the hydrodynamic modes in a dilute Bose-Einstein condensate. The condensate has six hydrodynamic modes, two of which are decaying shear modes related to the viscosity, and two pairs pairs of sound modes which undergo an avoided crossing as the equilibrium temperature is varied. The two pairs of sound modes decay at very different rates, except in the neighborhood of the avoided crossing, where the identity of the longest-lived mode switches. The predicted speed and lifetime of the longest-lived sound mode are consistent with recent experimental observations on sound in an 87Rb Bose-Einstein condensate. The strong depedence of the decay rates on temperature implies a possible new method for determining the temperature of Bose-Einstein condensates. The authors wish to thank the Robert A. Welch Foundation Grant No. F-1051 for support of this work.

  12. Bose-Einstein correlations in W-pair decays

    NASA Astrophysics Data System (ADS)

    Barate, R.; Decamp, D.; Ghez, P.; Goy, C.; Jezequel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Alemany, R.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, L.; Graugés, E.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, L. M.; Morawitz, P.; Pacheco, A.; Riu, I.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Boix, G.; Buchmüller, O.; Cattaneo, M.; Cerutti, F.; Ciulli, V.; Davies, G.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Greening, T. C.; Halley, A. W.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kado, M.; Leroy, O.; Maley, P.; Mato, P.; Minten, A.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Schmitt, M.; Schneider, O.; Spagnolo, P.; Tejessy, W.; Teubert, F.; Tournefier, E.; Valassi, A.; Wright, A. E.; Ajaltouni, Z.; Badaud, F.; Chazelle, G.; Deschamps, O.; Dessagne, S.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Pascolo, J. M.; Perret, P.; Podlyski, F.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Swynghedauw, M.; Tanaka, R.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Corden, M.; Georgiopoulos, C.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Chalmers, M.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Raeven, B.; Smith, D.; Teixeira-Dias, P.; Thompson, A. S.; Ward, J. J.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Leibenguth, G.; Putzer, A.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Marinelli, N.; Martin, E. B.; Nash, J.; Nowell, J.; Przysiezniak, H.; Sciabà, A.; Sedgbeer, J. K.; Thompson, J. C.; Thomson, E.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Buck, P. G.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Robertson, N. A.; Smizanska, M.; Williams, M. I.; Giehl, I.; Hölldorfer, F.; Jakobs, K.; Kleinknecht, K.; Kröcker, M.; Müller, A.-S.; Nürnberger, H.-A.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Carr, J.; Coyle, P.; Ealet, A.; Fouchez, D.; Payre, P.; Rousseau, D.; Tilquin, A.; Aleppo, M.; Antonelli, M.; Gilardoni, S.; Ragusa, F.; Büscher, V.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Mannert, C.; Männer, W.; Moser, H.-G.; Schael, S.; Settles, R.; Seywerd, H.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Azzurri, P.; Boucrot, J.; Callot, O.; Chen, S.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, P.; Jacholkowska, A.; Lefrançois, J.; Serin, L.; Veillet, J.-J.; Videau, I.; de Vivie de Régie, J.-B.; Zerwas, D.; Bagliesi, G.; Boccali, T.; Bozzi, C.; Calderini, G.; Dell'Orso, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Sguazzoni, G.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Coles, J.; Cowan, G.; Green, M. G.; Hutchcroft, D. E.; Jones, L. T.; Medcalf, T.; Strong, J. A.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Bloch-Devaux, B.; Colas, P.; Fabbro, B.; Faïf, G.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Seager, P.; Trabelsi, A.; Tuchming, B.; Vallage, B.; Black, S. N.; Dann, J. H.; Loomis, C.; Kim, H. Y.; Konstantinidis, N.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Misiejuk, A.; Prange, G.; Sieler, U.; Borean, C.; Giannini, G.; Gobbo, B.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Williams, R. W.; Armstrong, S. R.; Elmer, P.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A., III; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; von Wimmersperg-Toeller, J. H.; Wu, S. L.; Wu, X.; Zobernig, G.

    2000-04-01

    Bose-Einstein correlations are studied in semileptonic (WW-->qq¯lν) and fully hadronic (WW-->qq¯qq¯) W-pair decays with the ALEPH detector at LEP at centre-of-mass energies of 172, 183 and 189 GeV. They are compared with those made at the Z peak after correction for the different flavour compositions. A Monte Carlo model of Bose-Einstein correlations based on the JETSET hadronization scheme was tuned to the Z data and reproduces the correlations in the WW-->qq¯lν events. The same Monte Carlo reproduces the correlations in the WW-->qq¯qq¯ channel assuming independent fragmentation of the two W's. A variant of this model with Bose-Einstein correlations between decay products of different W's is disfavoured.

  13. Bose-Einstein condensation mechanism in economic system

    NASA Astrophysics Data System (ADS)

    Xu, Jianping

    2015-06-01

    This paper starts from modifying the kinetic exchange model and ends with making a parallel between economic crisis and the Bose-Einstein condensation. By introducing a parameter δ, we incorporate the time influence into the Bose-Einstein statistics. And δ is found to represent the technology level in an economy. δ's growth in time enlarges the rich and poor gap and induces economic crisis in free market despite the fact that average living standard is raised. Then we find the “δ-Te-Entropy” dilemma which features a strong implication of the second law of thermodynamics. The dilemma means when an economy is isolated the entropy grows and synergetically Te and δ grow inducing the Bose-Einstein condensation, i.e., economic crisis while for open economy the dilemma breaks. Then we raise the question: What would happen if the world economy as a whole became isolated with ultimately omnibearing globalization?

  14. Evidence of Bose-Einstein Condensation in solid helium

    NASA Astrophysics Data System (ADS)

    Chan, Moses H. W.

    2005-03-01

    The onset of superfluidity in liquid He-4 below 2.176K is associated with Bose-Einstein condensation where He-4 atoms condensed into a single momentum state and acquire quantum mechanical coherence over macroscopic length scales. Bose- Einstein condensation of alkali atoms in the vapor phase was achieved in 1995 and there is strong evidence for superfluidity in these systems. Perhaps counter to intuition, superfluid-like behavior is thought possible even in solid helium. Recent high Q torsional oscillator measurements found evidence of superflow in solid helium confined in porous media (1) and in bulk solid helium (2), indicating Bose-Einstein condensation very likely occurs in all three phases of matter. (1) E. Kim and M. H. W. Chan, Nature 427, 225 (2004) (2) E. Kim and M. H. W. Chan, Science 305, 1941 (2004).

  15. The effect of adiabaticity on strongly quenched Bose Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Ling, Hong; Kain, Ben

    2015-05-01

    We study the properties of a Bose-Einstein condensate following a deep quench to a large scattering length during which the condensate fraction nc changes with time. We construct a closed set of equations that highlight the role of the adiabaticity or equivalently, dnc/dt, the rate change of nc, which is to induce an (imaginary) effective interaction between quasiparticles. We show analytically that such a system supports a steady state characterized by a constant condensate density and a steady but periodically changing momentum distribution, whose time average is described exactly by the generalized Gibbs ensemble. We discuss how the nc -induced effective interaction, which cannot be ignored on the grounds of the adiabatic approximation for modes near the gapless Goldstone mode, can significantly affect condensate populations and Tan's contact for a Bose gas that has undergone a deep quench. In particular, we find that even when the Bose gas is quenched to unitarity, nc(t) does not completely deplete, approaching, instead, to a steady state with a finite condensate fraction. ITAMP, Harvard-Smithsonian Center for Astrophysics; KITP, University of Santa Barbara.

  16. Coupling a single electron to a Bose-Einstein condensate.

    PubMed

    Balewski, Jonathan B; Krupp, Alexander T; Gaj, Anita; Peter, David; Büchler, Hans Peter; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman

    2013-10-31

    The coupling of electrons to matter lies at the heart of our understanding of material properties such as electrical conductivity. Electron-phonon coupling can lead to the formation of a Cooper pair out of two repelling electrons, which forms the basis for Bardeen-Cooper-Schrieffer superconductivity. Here we study the interaction of a single localized electron with a Bose-Einstein condensate and show that the electron can excite phonons and eventually trigger a collective oscillation of the whole condensate. We find that the coupling is surprisingly strong compared to that of ionic impurities, owing to the more favourable mass ratio. The electron is held in place by a single charged ionic core, forming a Rydberg bound state. This Rydberg electron is described by a wavefunction extending to a size of up to eight micrometres, comparable to the dimensions of the condensate. In such a state, corresponding to a principal quantum number of n = 202, the Rydberg electron is interacting with several tens of thousands of condensed atoms contained within its orbit. We observe surprisingly long lifetimes and finite size effects caused by the electron exploring the outer regions of the condensate. We anticipate future experiments on electron orbital imaging, the investigation of phonon-mediated coupling of single electrons, and applications in quantum optics.

  17. Symmetry breaking and singularity structure in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Commeford, K. A.; Garcia-March, M. A.; Ferrando, A.; Carr, Lincoln D.

    2012-08-01

    We determine the trajectories of vortex singularities that arise after a single vortex is broken by a discretely symmetric impulse in the context of Bose-Einstein condensates in a harmonic trap. The dynamics of these singularities are analyzed to determine the form of the imprinted motion. We find that the symmetry-breaking process introduces two effective forces: a repulsive harmonic force that causes the daughter trajectories to be ejected from the parent singularity and a Magnus force that introduces a torque about the axis of symmetry. For the analytical noninteracting case we find that the parent singularity is reconstructed from the daughter singularities after one period of the trapping frequency. The interactions between singularities in the weakly interacting system do not allow the parent vortex to be reconstructed. Analytic trajectories were compared to the actual minima of the wave function, showing less than 0.5% error for an impulse strength of v=0.00005. We show that these solutions are valid within the impulse regime for various impulse strengths using numerical integration of the Gross-Pitaevskii equation. We also show that the actual duration of the symmetry-breaking potential does not significantly change the dynamics of the system as long as the strength is below v=0.0005.

  18. Are Quasiparticles and Phonons Identical in Bose-Einstein Condensates?

    NASA Astrophysics Data System (ADS)

    Tsutsui, Kazumasa; Kato, Yusuke; Kita, Takafumi

    2016-12-01

    We study an interacting spinless Bose-Einstein condensate to clarify theoretically whether the spectra of its quasiparticles (one-particle excitations) and collective modes (two-particle excitations) are identical, as concluded by Gavoret and Nozières [Ann. Phys. (N.Y.) 28, 349 (1964)]. We derive analytic expressions for their first and second moments so as to extend the Bijl-Feynman formula for the peak of the collective-mode spectrum to its width (inverse lifetime) and also to the one-particle channel. The obtained formulas indicate that the width of the collective-mode spectrum manifestly vanishes in the long-wavelength limit, whereas that of the quasiparticle spectrum apparently remains finite. We also evaluate the peaks and widths of the two spectra numerically for a model interaction potential in terms of the Jastrow wave function optimized by a variational method. It is thereby found that the width of the quasiparticle spectrum increases towards a constant as the wavenumber decreases. This marked difference in the spectral widths implies that the two spectra are distinct. In particular, the lifetime of the quasiparticles remains finite even in the long-wavelength limit.

  19. Nonlinear Phenomena in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Carr, Lincoln D.

    2008-03-01

    We present a medley of results from the last three years on nonlinear phenomena in BECs [1]. These include exact dynamics of multi-component condensates in optical lattices [2], vortices and ring solitons [3], macroscopic quantum tunneling [4], nonlinear band theory [5], and a pulsed atomic soliton laser [6]. 1. Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment, ed. P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer-Verlag, to appear, 2008) -- see L. D. Carr and Joachim Brand, e-print arXiv:0705.1139 (2007); Joachim Brand, L. D. Carr, B. P. Anderson, e-print arXiv:0705.1341 (2007). 2. R. Mark Bradley, James E. Bernard, and L. D. Carr, e-print arXiv:0711.1896 (2007). 3. G. Herring, L. D. Carr, R. Carretero-Gonzalez, P. G. Kevrekidis, D. J. Frantzeskakis, e-print arXiv:0709.2193 (2007); L. D. Carr and C. W. Clark, Phys. Rev. A v. 74, p.043613 (2006); L. D. Carr and C. W. Clark, Phys. Rev. Lett. v. 97, p.010403 (2006). 4. L. D. Carr, M. J. Holland, and B. A. Malomed, J. Phys. B: At. Mol. Opt. Phys., v.38, p.3217 (2005) 5. B. T. Seaman, L. D. Carr, and M. J. Holland, Phys. Rev. A, v. 71, p.033622 (2005). 6. L. D. Carr and J. Brand, Phys. Rev. A, v.70, p.033607 (2004); L. D. Carr and J. Brand, Phys. Rev. Lett., v.92, p.040401 (2004).

  20. Vortices in a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Haljan, Paul C.

    2004-05-01

    Since the advent of Bose-Einstein condensation in the dilute alkalis, there has been considerable interest in observing effects in atomic condensates akin to the hallmark effects associated with superfluidity and superconductivity. In particular, the study of quantized vortices and vortex lattices represents an important connection between the traditional ``super" systems such as liquid Helium and this new atomic system. This thesis explores some of the first vortex experiments in a condensate of magnetically trapped Rubidium-87. Single vortex lines and rings are created using a wavefunction engineering technique, which is an ideal starting point to study the dynamical behavior of vortices within the condensate. An entirely different approach of ``intrinsic nucleation" has been developed to create rapidly rotating condensates with large amounts of vorticity. A novel variation of forced evaporation is used to simultaneously cool and spin up an ultracold gas. In this way, condensates can be formed that are rotating in excess of 95% of the centrifugal limit and contain large, extraordinarily regular lattices of well over 100 vortices. Direct detection of the vortex cores makes it possible to study the microscopic structure of the vortex arrangements both at equilibrium and under dynamical conditions where severe applied stresses distort the lattice far from its equilibrium configuration. In conclusion, the techniques developed in this work have helped to open up a new area of rotating condensate physics and, in the future, may lead to regimes of extreme rotation and quantum Hall physics. This work was performed at the University of Colorado, Boulder, under the supervision of Prof. Eric A. Cornell.

  1. Ultrarelativistic Bose-Einstein gas on Lorentz symmetry violation

    NASA Astrophysics Data System (ADS)

    de Sales, J. A.; Costa-Soares, T.; Vasquez Otoya, V. J.

    2012-11-01

    In this paper, we study the effects of Lorentz Symmetry Breaking on the thermodynamic properties of ideal gases. Inspired by the dispersion relation coming from the Carroll-Field-Jackiw model for Electrodynamics with Lorentz and CPT violation term, we compute the thermodynamics quantities for a Boltzmann, Fermi-Dirac and Bose-Einstein distributions. Two regimes are analyzed: the large and the small Lorentz violation. In the first case, we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For Bose-Einstein gases, a condensation in both regimes can be found.

  2. Quantum and thermal fluctuations of trapped Bose-Einstein condensates

    SciTech Connect

    Kruglov, V.I.; Collett, M.J.; Olsen, M.K.

    2005-09-15

    We quantize a semiclassical system defined by the Hamiltonian obtained from the asymptotic self-similar solution of the Gross-Pitaevskii equation for a trapped Bose-Einstein condensate with a linear gain term. On the basis of a Schroedinger equation derived in a space of ellipsoidal parameters, we analytically calculate the quantum mechanical and thermal variance in the ellipsoidal parameters for Bose-Einstein condensates in various shapes of trap. We show that, except for temperatures close to zero, dimensionless dispersions do not depend on the frequencies of the trap and they have the same dependence on dimensionless temperatures.

  3. Dynamical thermalization of Bose-Einstein condensate in Bunimovich stadium

    NASA Astrophysics Data System (ADS)

    Ermann, L.; Vergini, E.; Shepelyansky, D. L.

    2015-09-01

    We study numerically the wave function evolution of a Bose-Einstein condensate in a Bunimovich stadium billiard being governed by the Gross-Pitaevskii equation. We show that for a moderate nonlinearity, above a certain threshold, there is emergence of dynamical thermalization which leads to the Bose-Einstein probability distribution over the linear eigenmodes of the stadium. This distribution is drastically different from the energy equipartition over oscillator degrees of freedom which would lead to the ultra-violet catastrophe. We argue that this interesting phenomenon can be studied in cold-atom experiments.

  4. Manipulating localized matter waves in multicomponent Bose-Einstein condensates.

    PubMed

    Manikandan, K; Muruganandam, P; Senthilvelan, M; Lakshmanan, M

    2016-03-01

    We analyze vector localized solutions of two-component Bose-Einstein condensates (BECs) with variable nonlinearity parameters and external trap potentials through a similarity transformation technique which transforms the two coupled Gross-Pitaevskii equations into a pair of coupled nonlinear Schrödinger equations with constant coefficients under a specific integrability condition. In this analysis we consider three different types of external trap potentials: a time-independent trap, a time-dependent monotonic trap, and a time-dependent periodic trap. We point out the existence of different interesting localized structures; namely, rogue waves, dark- and bright-soliton rogue waves, and rogue-wave breatherlike structures for the above three cases of trap potentials. We show how the vector localized density profiles in a constant background get deformed when we tune the strength of the trap parameter. Furthermore, we investigate the nature of the trajectories of the nonautonomous rogue waves. We also construct the dark-dark rogue wave solution for the repulsive-repulsive interaction of two-component BECs and analyze the associated characteristics for the three different kinds of traps. We then deduce single-, two-, and three-composite rogue waves for three-component BECs and discuss the correlated characteristics when we tune the strength of the trap parameter for different trap potentials.

  5. Manipulating localized matter waves in multicomponent Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Manikandan, K.; Muruganandam, P.; Senthilvelan, M.; Lakshmanan, M.

    2016-03-01

    We analyze vector localized solutions of two-component Bose-Einstein condensates (BECs) with variable nonlinearity parameters and external trap potentials through a similarity transformation technique which transforms the two coupled Gross-Pitaevskii equations into a pair of coupled nonlinear Schrödinger equations with constant coefficients under a specific integrability condition. In this analysis we consider three different types of external trap potentials: a time-independent trap, a time-dependent monotonic trap, and a time-dependent periodic trap. We point out the existence of different interesting localized structures; namely, rogue waves, dark- and bright-soliton rogue waves, and rogue-wave breatherlike structures for the above three cases of trap potentials. We show how the vector localized density profiles in a constant background get deformed when we tune the strength of the trap parameter. Furthermore, we investigate the nature of the trajectories of the nonautonomous rogue waves. We also construct the dark-dark rogue wave solution for the repulsive-repulsive interaction of two-component BECs and analyze the associated characteristics for the three different kinds of traps. We then deduce single-, two-, and three-composite rogue waves for three-component BECs and discuss the correlated characteristics when we tune the strength of the trap parameter for different trap potentials.

  6. Vortices in spin-orbit-coupled Bose-Einstein condensates

    SciTech Connect

    Radic, J.; Sedrakyan, T. A.; Galitski, V.; Spielman, I. B.

    2011-12-15

    Realistic methods to create vortices in spin-orbit-coupled Bose-Einstein condensates are discussed. It is shown that, contrary to common intuition, rotation of the trap containing a spin-orbit condensate does not lead to an equilibrium state with static vortex structures but gives rise instead to nonequilibrium behavior described by an intrinsically time-dependent Hamiltonian. We propose here the following alternative methods to induce thermodynamically stable static vortex configurations: (i) to rotate both the lasers and the anisotropic trap and (ii) to impose a synthetic Abelian field on top of synthetic spin-orbit interactions. Effective Hamiltonians for spin-orbit condensates under such perturbations are derived for most currently known realistic laser schemes that induce synthetic spin-orbit couplings. The Gross-Pitaevskii equation is solved for several experimentally relevant regimes. The new interesting effects include spatial separation of left- and right-moving spin-orbit condensates, the appearance of unusual vortex arrangements, and parity effects in vortex nucleation where the topological excitations are predicted to appear in pairs. All these phenomena are shown to be highly nonuniversal and depend strongly on a specific laser scheme and system parameters.

  7. PHD TUTORIAL: Finite-temperature models of Bose Einstein condensation

    NASA Astrophysics Data System (ADS)

    Proukakis, Nick P.; Jackson, Brian

    2008-10-01

    The theoretical description of trapped weakly interacting Bose-Einstein condensates is characterized by a large number of seemingly very different approaches which have been developed over the course of time by researchers with very distinct backgrounds. Newcomers to this field, experimentalists and young researchers all face a considerable challenge in navigating through the 'maze' of abundant theoretical models, and simple correspondences between existing approaches are not always very transparent. This tutorial provides a generic introduction to such theories, in an attempt to single out common features and deficiencies of certain 'classes of approaches' identified by their physical content, rather than their particular mathematical implementation. This tutorial is structured in a manner accessible to a non-specialist with a good working knowledge of quantum mechanics. Although some familiarity with concepts of quantum field theory would be an advantage, key notions, such as the occupation number representation of second quantization, are nonetheless briefly reviewed. Following a general introduction, the complexity of models is gradually built up, starting from the basic zero-temperature formalism of the Gross-Pitaevskii equation. This structure enables readers to probe different levels of theoretical developments (mean field, number conserving and stochastic) according to their particular needs. In addition to its 'training element', we hope that this tutorial will prove useful to active researchers in this field, both in terms of the correspondences made between different theoretical models, and as a source of reference for existing and developing finite-temperature theoretical models.

  8. Shock Waves in a Bose-Einstein Condensate

    NASA Technical Reports Server (NTRS)

    Kulikov, Igor; Zak, Michail

    2005-01-01

    A paper presents a theoretical study of shock waves in a trapped Bose-Einstein condensate (BEC). The mathematical model of the BEC in this study is a nonlinear Schroedinger equation (NLSE) in which (1) the role of the wave function of a single particle in the traditional Schroedinger equation is played by a space- and time-dependent complex order parameter (x,t) proportional to the square root of the density of atoms and (2) the atoms engage in a repulsive interaction characterized by a potential proportional to | (x,t)|2. Equations that describe macroscopic perturbations of the BEC at zero temperature are derived from the NLSE and simplifying assumptions are made, leading to equations for the propagation of sound waves and the transformation of sound waves into shock waves. Equations for the speeds of shock waves and the relationships between jumps of velocity and density across shock fronts are derived. Similarities and differences between this theory and the classical theory of sound waves and shocks in ordinary gases are noted. The present theory is illustrated by solving the equations for the example of a shock wave propagating in a cigar-shaped BEC.

  9. Rapidly rotating Bose-Einstein condensates in strongly anharmonic traps

    SciTech Connect

    Correggi, M.; Rindler-Daller, T.; Yngvason, J.

    2007-04-15

    We study a rotating Bose-Einstein condensate in a strongly anharmonic trap (flat trap with a finite radius) in the framework of two-dimensional Gross-Pitaevskii theory. We write the coupling constant for the interactions between the gas atoms as 1/{epsilon}{sup 2} and we are interested in the limit {epsilon}{yields}0 (Thomas-Fermi limit) with the angular velocity {omega} depending on {epsilon}. We derive rigorously the leading asymptotics of the ground state energy and the density profile when {omega} tends to infinity as a power of 1/{epsilon}. If {omega}({epsilon})={omega}{sub 0}/{epsilon} a ''hole'' (i.e., a region where the density becomes exponentially small as 1/{epsilon}{yields}{infinity}) develops for {omega}{sub 0} above a certain critical value. If {omega}({epsilon})>>1/{epsilon} the hole essentially exhausts the container and a ''giant vortex'' develops with the density concentrated in a thin layer at the boundary. While we do not analyze the detailed vortex structure we prove that rotational symmetry is broken in the ground state for const vertical bar log {epsilon} vertical bar <{omega}({epsilon}) < or approx. const/{epsilon}.

  10. Route to Quantum Turbulence in Trapped Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Allen, A.; Parker, Nick; Proukakis, Nick; Barenghi, Carlo

    2013-05-01

    Turbulence in superfluid Helium has been the subject of many experimental and theoretical investigations (for review see e.g. L. Skrbek and K.R. Sreenivasan, Phys. of Fluids 24, 011301 (2012)) and recently, experimentalists have been able to visualize vortex lines, reconnection events and Kelvin waves (E. Fonda et al. arXiv:1210.5194). Weakly interacting Bose-Einstein condensates however, present a unique opportunity to resolve the structure of vortices and in turn study the dynamics of a vortex tangle (as has recently been created in an atomic cloud E.A.L. Henn et al. Phys. Rev. Lett 103, 04301 (2009)). We investigate ways of generating turbulence in atomic systems by numerically stirring the condensate using a Gaussian `spoon' (analogous to a laser beam in the experiments), and study the isotropy of the resulting vortex tangle depending on whether the path the spoon stirs is circular or random. We model the system using the Gross-Pitaevskii Equation and extend our analysis to finite temperature using the Zaremba-Nikuni-Griffin (ZNG) formalism (E. Zaremba et al. Jour. Low Temp. Phys. 116, 277 (1999)), whereby the full dynamics of the noncondensate atoms are described by a semiclassical Boltzmann equation.

  11. The Bose-Einstein correlations in CDFII experiment

    SciTech Connect

    Lovás, Lubomír

    2008-01-01

    We present the results of a study of p$\\bar{p}$ collisions at √s = 1.96 TeV collected by the CDF-II experiment at Tevatron collider. The Bose-Einstein correlations of the π±π± two boson system have been studied in the minimum-bias high-multiplicity events. The research was carried out on the sample at the size of 173761 events. The two pion correlations have been retrieved. The final results were corrected to the coulomb interactions. Two different reference samples were compared and discussed. A significant two-pion correlation enhancement near origin is observed. This enhancement effect has been used to evaluate the radius of the two-pion emitter source. We have used the TOF detector to distinguish between π and K mesons. The C2(Q) function parameters have also been retrieved for the sample containing only tagged π mesons. A comparison between four different parametrizations based on two diff t theoretical approaches of the C2(Q) function is given.

  12. Universal Analytical Solutions for Mixtures of Rotating Bose-Einstein Condensates

    SciTech Connect

    Papenbrock, Thomas F; Reimann, S. M.; Kavoulakis, G. M.

    2012-01-01

    We derive exact analytical results for the many-body wave functions and energies of harmonically trapped two-component Bose-Einstein condensates with weak repulsive interactions under rotation. The wave functions are universal as they do not depend on the matrix elements of the two-body interaction. A comparison with the results from numerical diagonalization shows that the analytical solutions describe the ground state, as well as a set of low-lying excited states for repulsive contact interactions, Coulomb interactions, and the repulsive interactions between aligned dipoles.

  13. Dynamics of a Bose-Einstein condensate in a horizontally vibrating shallow optical lattice

    SciTech Connect

    Valizadeh, A.; Jahanbani, Kh.; Kolahchi, M. R.

    2010-02-15

    We consider a solitonic solution of the self-attractive Bose-Einstein condensate in a one-dimensional external potential of a shallow optical lattice with large periodicity when the lattice is horizontally shaken. We investigate the dynamics of the bright soliton through the properties of the fixed points. The special type of bifurcation results in a simple criterion for the stability of the fixed points depending only on the amplitude of the shaking lattice. Because of the similarity of the equations with those of an ac-driven Josephson junction, some results may find applications in other branches of physics.

  14. Dynamics of a Bose-Einstein condensate in a horizontally vibrating shallow optical lattice

    NASA Astrophysics Data System (ADS)

    Valizadeh, A.; Jahanbani, Kh.; Kolahchi, M. R.

    2010-02-01

    We consider a solitonic solution of the self-attractive Bose-Einstein condensate in a one-dimensional external potential of a shallow optical lattice with large periodicity when the lattice is horizontally shaken. We investigate the dynamics of the bright soliton through the properties of the fixed points. The special type of bifurcation results in a simple criterion for the stability of the fixed points depending only on the amplitude of the shaking lattice. Because of the similarity of the equations with those of an ac-driven Josephson junction, some results may find applications in other branches of physics.

  15. Bright-matter solitons in a uniformly feeded Bose-Einstein condensate with expulsive harmonic potential

    SciTech Connect

    Dikande, Alain Moiese

    2008-07-15

    The Gross-Pitaevskii equation, which describes the dynamics of a one-dimensional uniformly feeded attractive Bose-Einstein condensate in an expulsive potential of arbitrary harmonic shape -a{sub 2}x{sup 2}+a{sub 1}x, is solved analytically following the inverse scattering transform method. Within this approach, bright-matter waves are obtained as exact envelope-soliton solutions of the nonlinear Schroedinger equation with a complex harmonic potential. The envelope shapes mimic double-lump pulses of unequal amplitudes symmetric with respect to the potential maximum, moving simultaneously at nonconstant accelerations with amplitudes that vary in time.

  16. Multiply quantized and fractional skyrmions in a binary dipolar Bose-Einstein condensate under rotation

    NASA Astrophysics Data System (ADS)

    Dong, Biao; Sun, Qing; Liu, Wu-Ming; Ji, An-Chun; Zhang, Xiao-Fei; Zhang, Shou-Gang

    2017-07-01

    We consider a binary dipolar Bose-Einstein condensate with repulsive contact and dipolar interactions under rotation. Our results show that the interplay among short-range interaction, long-range interaction, and rotation can give rise to a rich variety of topological configurations, including giant skyrmions with multiply topological charges and skyrmion-vortex lattices. In particular, we find that for fixed rotation frequencies, tuning the short- and long-range interactions can derive novel ground-state phases, such as a meron pair composed of two fractional skyrmions and a skyrmion with topological charge Q =2 centered in giant skyrmions.

  17. Multiple condensed phases in attractively interacting Bose systems

    NASA Astrophysics Data System (ADS)

    Männel, M.; Morawetz, K.; Lipavský, P.

    2010-03-01

    We investigate a Bose gas with finite-range interaction using a scheme to eliminate unphysical processes in the T-matrix approximation. In this way the corrected T-matrix becomes suitable to calculate properties below the critical temperature. For attractive interaction, an Evans-Rashid transition occurs between a quasi-ideal Bose gas and a Bardeen-Cooper-Schrieffer-like phase with a gap dispersion. The gap decreases with increasing density and vanishes at a critical density where the single-particle dispersion becomes linear for small momenta, indicating Bose-Einstein condensation. The investigation of the pressure shows, however, that the mentioned quantum phase transitions might be inaccessible due to a preceding first-order transition.

  18. Oscillatory decay of a two-component bose-einstein condensate.

    PubMed

    Kohler, Sigmund; Sols, Fernando

    2002-08-05

    We study the decay of a two-component Bose-Einstein condensate with negative effective interaction energy. With a decreasing atom number due to losses, the atom-atom interaction becomes less important and the system undergoes a transition from a bistable Josephson regime to the monostable Rabi regime, displaying oscillations in phase and number. We study the equations of motion and derive an analytical expression for the oscillation amplitude. A quantum trajectory simulation reveals that the classical description fails for low loss rates, as expected from analytical considerations. Observation of the proposed effect will provide evidence for negative effective interaction.

  19. Stability analysis for n-component Bose-Einstein condensate

    SciTech Connect

    Roberts, David C.; Ueda, Masahito

    2006-05-15

    We derive the dynamic and thermodynamic stability conditions for dilute multicomponent Bose-Einstein condensates (BECs). These stability conditions, generalized for n-component BECs, are found to be equivalent and are shown to be consistent with the phase diagrams of two- and three-component condensates that are derived from energetic arguments.

  20. Feshbach resonance induced shock waves in Bose-Einstein condensates.

    PubMed

    Pérez-García, Víctor M; Konotop, Vladimir V; Brazhnyi, Valeriy A

    2004-06-04

    We propose a method for generating shock waves in Bose-Einstein condensates by rapidly increasing the value of the nonlinear coefficient using Feshbach resonances. We show that in a cigar-shaped condensate there exist primary (transverse) and secondary (longitudinal) shock waves. We analyze how the shocks are generated in multidimensional scenarios and describe the related phenomenology.

  1. Bose-Einstein correlation within the framework of hadronic mechanics

    SciTech Connect

    Burande, Chandrakant S.

    2015-03-10

    The Bose-Einstein correlation is the phenomenon in which protons and antiprotons collide at extremely high energies; coalesce one into the other resulting into the fireball of finite dimension. They annihilate each other and produces large number of mesons that remain correlated at distances very large compared to the size of the fireball. It was believed that Einstein’s special relativity and relativistic quantum mechanics are the valid frameworks to represent this phenomenon. Although, these frameworks are incomplete and require arbitrary parameters (chaoticity) to fit the experimental data which are prohibited by the basic axioms of relativistic quantum mechanics, such as that for the vacuum expectation values. Moreover, correlated mesons can not be treated as a finite set of isolated point-like particles because it is non-local event due to overlapping of wavepackets. Therefore, the Bose-Einstein correlation is incompatible with the axiom of expectation values of quantum mechanics. In contrary, relativistic hadronic mechanics constructed by Santilli allows an exact representation of the experimental data of the Bose-Einstein correlation and restore the validity of the Lorentz and Poincare symmetries under nonlocal and non-Hamiltonian internal effects. Further, F. Cardone and R. Mignani observed that the Bose-Einstein two-point correlation function derived by Santilli is perfectly matched with experimental data at high energy.

  2. Enhanced factoring with a bose-einstein condensate.

    PubMed

    Sadgrove, Mark; Kumar, Sanjay; Nakagawa, Ken'ichi

    2008-10-31

    We present a novel method to realize analog sum computation with a Bose-Einstein condensate in an optical lattice potential subject to controlled phase jumps. We use the method to implement the Gauss sum algorithm for factoring numbers. By exploiting higher order quantum momentum states, we are able to improve the algorithm's accuracy beyond the limits of the usual classical implementation.

  3. Quantum Phase Diffusion of a Bose-Einstein Condensate

    SciTech Connect

    Lewenstein, M.; You, L. |

    1996-10-01

    We discuss the quantum properties of the Bose-Einstein condensate of a dilute gas of atoms in a trap. We show that the phase of the condensate undergoes quantum diffusion which can be detected in far off-resonant light scattering experiments. {copyright} {ital 1996 The American Physical Society.}

  4. Symmetry-assisted vorticity control in Bose-Einstein condensates

    SciTech Connect

    Perez-Garcia, Victor M.; Garcia-March, Miguel A.; Ferrando, Albert

    2007-03-15

    Using group-theoretical methods and numerical simulations, we show how to act on the topological charge of individual vortices in Bose-Einstein condensates by using control potentials with appropriate discrete symmetries. As examples of our methodology we study charge inversion and vortex erasing by acting on a set of control-laser Gaussian beams generating optical dipole traps.

  5. Topological aspects in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ueda, Masahito

    2014-12-01

    This article overviews topological excitations in spinor Bose-Einstein condensates of dilute atomic gases. Various types of line defects, point defects and skyrmions are discussed. A brief review of homotopy theory is presented for use in the classification of possible topological excitations in individual quantum phases. Some recent experiments are also reviewed.

  6. Time symmetry breaking in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Mendonça, J. T.; Gammal, A.

    2017-09-01

    We consider different processes leading to time symmetry breaking in a Bose-Einstein condensate. Our approach provides a global description of time symmetry breaking, based on the equations of a thermal condensate. This includes quenching and expansion of the condensate, the Kibble-Zurek mechanism associated with the creation of vorticity, the dynamical Casimir effect and the formation of time crystals.

  7. Bose-Einstein condensates from scalar field dark matter

    SciTech Connect

    Urena-Lopez, L. Arturo

    2010-12-07

    We review the properties of astrophysical and cosmological relevance that may arise from the bosonic nature of scalar field dark matter models. The key property is the formation of Bose-Einstein condensates, but we also consider the presence of non-empty excited states that may be relevant for the description of scalar field galaxy halos and the properties of rotation curves.

  8. Exact soliton-on-plane-wave solutions for two-component Bose-Einstein condensates.

    PubMed

    Li, Lu; Malomed, Boris A; Mihalache, Dumitru; Liu, W M

    2006-06-01

    By means of the Darboux transformation, we obtain analytical solutions for a soliton set on top of a plane-wave background in coupled Gross-Pitaevskii equations describing a binary Bose-Einstein condensate. We consider basic properties of the solutions with and without the cross interaction [cross phase modulation (XPM)] between the two components of the background. In the absence of the XPM, this solutions maintain properties of one-component condensates, such as the modulation instability (MI); in the presence of the cross interaction, the solutions exhibit different properties, such as restriction of the MI and soliton splitting.

  9. Exact soliton-on-plane-wave solutions for two-component Bose-Einstein condensates

    SciTech Connect

    Li Lu; Malomed, Boris A.; Mihalache, Dumitru; Liu, W. M.

    2006-06-15

    By means of the Darboux transformation, we obtain analytical solutions for a soliton set on top of a plane-wave background in coupled Gross-Pitaevskii equations describing a binary Bose-Einstein condensate. We consider basic properties of the solutions with and without the cross interaction [cross phase modulation (XPM)] between the two components of the background. In the absence of the XPM, this solutions maintain properties of one-component condensates, such as the modulation instability (MI); in the presence of the cross interaction, the solutions exhibit different properties, such as restriction of the MI and soliton splitting.

  10. Photon-assisted tunneling of a driven two-mode Bose-Einstein condensate

    SciTech Connect

    Xie Qiongtao; Rong Shiguang; Zhong Honghua; Lu Gengbiao; Hai Wenhua

    2010-08-15

    We investigate the photon-assisted tunneling of a Bose-Einstein condensate in a periodically driven double-well potential. It is shown that the energy levels become nonequidistant due to the presence of the interatomic interaction, thereby leading to the occurrences of the fractional photon resonances. Depending on whether the resonance frequency shifts with the interatomic interaction, two distinct types of resonances are identified: nonshifting resonances and shifting resonances. In particular, certain nonshifting fractional resonances show an odd-even sensitivity to the atom number.

  11. Semiclassical Hartree-Fock theory of a rotating Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Hassan, Ahmed S.; El-Badry, Azza M.; Soliman, Shemi S. M.

    2017-01-01

    In this paper, the thermodynamic behavior of a rotating Bose-Einstein condensation with non-zero interatomic interactions has been theoretically investigated. The analysis relied on a semiclassical Hartree-Fock approximation where an integral is performed over the phase space and function of the grand canonical ensemble is derived. Subsequently, this result is used to derive several thermodynamic quantities including the condensate fraction, critical temperature, entropy and heat capacity. Thereby, we investigated the effect of the rotation rate and interactions parameter on the thermodynamic behavior. The role of finite size is discussed. Our approach can be extended to consider the rotating condensate in optical potential.

  12. Bose-Einstein condensates in an optical cavity with sub-recoil bandwidth

    NASA Astrophysics Data System (ADS)

    Klinder, J.; Keßler, H.; Georges, Ch.; Vargas, J.; Hemmerich, A.

    2016-12-01

    This article provides a brief synopsis of our recent work on the interaction of Bose-Einstein condensates with the light field inside an optical cavity exhibiting a bandwidth on the order of the recoil frequency. Three different coupling scenarios are discussed giving rise to different physical phenomena at the borderline between the fields of quantum optics and many-body physics. This includes sub-recoil opto-mechanical cooling, cavity-controlled matter wave superradiance and the emergence of a superradiant superfluid or a superradiant Mott insulating many-body phase in a self-organized intra-cavity optical lattice with retarded infinite range interactions.

  13. Two-dimensional bright and dark-in-bright dipolar Bose-Einstein condensate solitons on a one-dimensional optical lattice

    NASA Astrophysics Data System (ADS)

    Adhikari, S. K.

    2016-08-01

    We study the statics and dynamics of anisotropic, stable, bright and dark-in-bright dipolar quasi-two-dimensional Bose-Einstein condensate (BEC) solitons on a one-dimensional (1D) optical-lattice (OL) potential. These solitons mobile in a plane perpendicular to a 1D OL trap can have both repulsive and attractive contact interactions. Dark-in-bright solitons are the excited states of bright solitons. The solitons, when subjected to a small perturbation, exhibit sustained breathing oscillation. Dark-in-bright solitons can be created by phase imprinting a bright soliton. At medium velocities the collision between two solitons is found to be quasi-elastic. Results are demonstrated by a numerical simulation of the three-dimensional mean-field Gross-Pitaevskii equation in three spatial dimensions employing realistic interaction parameters for a dipolar 164Dy BEC.

  14. Dynamics of Two-Component Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Baik, Eunsil

    I explored the vortex dynamics in homonuclear species two-component Bose-Einstein condensates (BECs) based on the knowledge of vortex dynamics in one-component BECs. The vortex dynamics in BECs depends on the background fields induced by different external potentials and other vortices. The motion of vortices is numerically computed and the numerical results are compared to the theoretical formulas where possible. In the study of the vortex-vortex interaction dynamics in one-component BECs, a power law relationship between the motion of the vortices and their separation distance is depicted. In addition to that, the relationship between the linear and the angular velocities of the vortices is found to be similar to the relationship between the tangential and the angular velocities of classical fluid vortices. In the case of two-component BEC dynamics, two different cases are studied: one without atomic inter-conversion between the two components and the other with atomic inter-conversion. The stability analysis of the two-component BECs is conducted to identify the stable regions as well as the regions of mixed and separated states. When a vortex is seeded in one component, this vortex induces a hump in the other component at the same location as the vortex, which leads to the vortex-hump dynamics. The vortex-hump-vortex-hump interaction dynamics without atomic inter-conversion depicts a power law relation between the motion of vortex-humps and the separation distance; whereas, the vortex-hump-vortex-hump interaction dynamics with atomic inter-conversion reveals a more complex relation between the motion of vortex-humps and the separation distance.

  15. Mixtures of ultracold gases: Fermi sea and Bose-Einstein condensate of lithium isotopes

    NASA Astrophysics Data System (ADS)

    Schreck, F.

    2003-03-01

    This thesis presents studies of quantum degenerate atomic gases of fermionic ^6Li and bosonic ^7Li. Degeneracy is reached by evaporative cooling of ^7Li in a strongly confining magnetic trap. Since at low temperatures direct evaporative cooling is not possible for a polarized fermionic gas, ^6Li is sympathetically cooled by thermal contact with ^7Li. In a first series of experiments both isotopes are trapped in their low-field seeking higher hyperfine states. A Fermi degeneracy of T/T_F=0.25(5) is achieved for 10^5 fermions. For more than 300 atoms, the ^7Li condensate collapses, due to the attractive interatomic interaction in this state. This limits the degeneracy reached for both species. To overcome this limit, in a second series of experiments ^7Li and ^6Li atoms are transferred to their low field seeking lower hyperfine states, where the boson-boson interaction is repulsive but weak. The inter-isotope collisions are used to thermalize the mixture. A ^7Li Bose-Einstein condensate (BEC) of 10^4 atoms immersed in a Fermi sea is produced. The BEC is quasi-one-dimensional and the thermal fraction can be negligible. The measured degeneracies are T/T_C=T/T_F=0.2(1). The temperature is measured using the bosonic thermal fraction, which vanishes at the lowest temperatures, limiting our measurement sensitivity. In a third series of experiments, the bosons are transferred into an optical trap and their internal state is changed to |F=1,m_F=1rangle, the lowest energy state. A Feshbach resonance is detected and used to produce a BEC with tunable atomic interactions. When the effective interaction between atoms is tuned to be small and attractive, we observe the formation of a matter-wave bright soliton. Propagation of the soliton without spreading over a macroscopic distance of 1.1 mm is observed. Mélanges de gaz ultrafroids: mer de Fermi et condensat de Bose-Einstein des isotopes du lithium Cette thèse décrit l'étude des gaz de fermions ^6Li et de bosons ^7Li dans le

  16. Gravitational collapse of Bose-Einstein condensate dark matter halos

    NASA Astrophysics Data System (ADS)

    Harko, Tiberiu

    2014-04-01

    We study the mechanisms of the gravitational collapse of the Bose-Einstein condensate dark matter halos, described by the zero temperature time-dependent nonlinear Schrödinger equation (the Gross-Pitaevskii equation), with repulsive interparticle interactions. By using a variational approach, and by choosing an appropriate trial wave function, we reformulate the Gross-Pitaevskii equation with spherical symmetry as Newton's equation of motion for a particle in an effective potential, which is determined by the zero-point kinetic energy, the gravitational energy, and the particles interaction energy, respectively. The velocity of the condensate is proportional to the radial distance, with a time-dependent proportionality function. The equation of motion of the collapsing dark matter condensate is studied by using both analytical and numerical methods. The collapse of the condensate ends with the formation of a stable configuration, corresponding to the minimum of the effective potential. The radius and the mass of the resulting dark matter object are obtained, as well as the collapse time of the condensate. The numerical values of these global astrophysical quantities, characterizing condensed dark matter systems, strongly depend on the two parameters describing the condensate, the mass of the dark matter particle, and of the scattering length, respectively. The stability of the condensate under small perturbations is also studied, and the oscillations frequency of the halo is obtained. Hence these results show that the gravitational collapse of the condensed dark matter halos can lead to the formation of stable astrophysical systems with both galactic and stellar sizes.

  17. Sonic horizon formation for oscillating Bose-Einstein condensates in isotropic harmonic potential

    PubMed Central

    Wang, Ying; Zhou, Yu; Zhou, Shuyu

    2016-01-01

    We study the sonic horizon phenomena of the oscillating Bose-Einstein condensates in isotropic harmonic potential. Based on the Gross-Pitaevskii equation model and variational method, we derive the original analytical formula for the criteria and lifetime of the formation of the sonic horizon, demonstrating pictorially the interaction parameter dependence for the occur- rence of the sonic horizon and damping effect of the system distribution width. Our analytical results corroborate quantitatively the particular features of the sonic horizon reported in previous numerical study. PMID:27922129

  18. Creation and counting of defects in a temperature-quenched Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Donadello, S.; Serafini, S.; Bienaimé, T.; Dalfovo, F.; Lamporesi, G.; Ferrari, G.

    2016-08-01

    We study the spontaneous formation of defects in the order parameter of a trapped ultracold bosonic gas while crossing the critical temperature for Bose-Einstein condensation at different rates. The system has the shape of an elongated ellipsoid, whose transverse width can be varied. For slow enough temperature quenches we find a power-law scaling of the average defect number with the quench rate, as predicted by the Kibble-Zurek mechanism. A breakdown of such a scaling is found for fast quenches, leading to a saturation of the average defect number. We suggest an explanation for this saturation in terms of the mutual interactions among defects.

  19. Propagation of collective modes in non-overlapping dipolar Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Gallemi, A.; Guilleumas, M.; Mayol, R.; Pi, M.

    2014-04-01

    We investigate long-range effects of the dipolar interaction in Bose-Einstein condensates by solving the time-dependent 3D Gross-Pitaevskii equation. We study the propagation of excitations between non-overlapping condensates when a collective mode is excited in one of the condensates. We obtain the frequency shifts due to the long-range character of the dipolar coupling for the bilayer and also the trilayer system when the dipolar mode is excited in one condensate. The propagation of the monopolar and quadrupolar modes are also investigated. The coupled-pendulum model is proposed to qualitatively explain the long range effects of the dipolar coupling.

  20. Inhomogeneous dark states of atomic-molecular Bose-Einstein condensates in trapping potentials

    SciTech Connect

    Cruz, H. A.; Konotop, V. V.

    2011-03-15

    We investigate possibilities of existence of inhomogeneous dark states of atomic-molecular Bose-Einstein condensates loaded in trap potentials. The system is described by three-coupled equations of the Gross-Pitaevskii type, which account for contributions of the kinetic energy, two-body interactions, and an external potential, and which govern the conversion between atoms and molecules in the stimulated Raman adiabatic passage. We report a class of trapping potentials allowing for the existence of localized stable dark states. The respective atomic and molecular distributions are computed, and their stability and dynamics are discussed.

  1. Quantum Coherent Atomic Tunneling between Two Trapped Bose-Einstein Condensates

    SciTech Connect

    Smerzi, A.; Fantoni, S.; Giovanazzi, S.

    1997-12-01

    We study the coherent atomic tunneling between two zero-temperature Bose-Einstein condensates (BEC) confined in a double-well magnetic trap. Two Gross-Pitaevskii equations for the self-interacting BEC amplitudes, coupled by a transfer matrix element, describe the dynamics in terms of the interwell phase difference and population imbalance. In addition to the anharmonic generalization of the familiar ac Josephson effect and plasma oscillations occurring in superconductor junctions, the nonlinear BEC tunneling dynamics sustains a self-maintained population imbalance: a novel {open_quotes}macroscopic quantum self-trapping{close_quotes} effect. {copyright} {ital 1997} {ital The American Physical Society}

  2. Generating ring dark solitons in two-component Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ji, Shen-Tong; Liu, Xue-Shen

    2014-01-01

    The dynamical evolution of two-component Bose-Einstein condensates trapped in cylindrical well is numerically investigated by solving the coupled Gross-Pitaevskii equations. We illustrate that, due to intercomponent interaction and different initial component populations (n1

  3. Phase diagram of a rotating Bose-Einstein condensate with anharmonic confinement

    SciTech Connect

    Jackson, A.D.; Kavoulakis, G.M.; Lundh, E.

    2004-05-01

    We examine the phase diagram of an effectively repulsive Bose-Einstein condensate of atoms that rotates in a quadratic-plus-quartic potential. With use of a variational method we identify the three possible phases of the system as a function of the rotational frequency of the trap and of the coupling constant. The derived phase diagram is shown to be universal and partly exact in the limit of weak interactions and small anharmonicity. The variational results are found to be consistent with numerical solutions of the Gross-Pitaevskii equation.

  4. Analytical solutions for the spin-1 Bose-Einstein condensate in a harmonic trap

    NASA Astrophysics Data System (ADS)

    Shi, Yu-Ren; Wang, Xue-Ling; Wang, Guang-Hui; Liu, Cong-Bo; Zhou, Zhi-Gang; Yang, Hong-Juan

    2013-06-01

    The homotopy analysis method and Galerkin spectral method are applied to find the analytical solutions for the Gross-Pitaevskii equations, a set of nonlinear Schrödinger equation used in simulation of spin-1 Bose-Einstein condensates trapped in a harmonic potential. We investigate the one-dimensional case and get the approximate analytical solutions successfully. Comparisons between the analytical solutions and the numerical solutions have been made. The results indicate that they are in agreement well with each other when the atomic interaction is weakly. We also find a class of exact solutions for the stationary states of the spin-1 system with harmonic potential for a special case.

  5. Dynamics and stability of Bose-Einstein solitons in tilted optical lattices

    SciTech Connect

    Diaz, E.; Dominguez-Adame, F.; Gaul, C.; Lima, R. P. A.; Mueller, C. A.

    2010-05-15

    Bloch oscillations of Bose-Einstein condensates realize sensitive matter-wave interferometers. We investigate the dynamics and stability of bright-soliton wave packets in one-dimensional tilted optical lattices with a modulated mean-field interaction g(t). By means of a time-reversal argument, we prove the stability of Bloch oscillations of breathing solitons that would be quasistatically unstable. Floquet theory shows that these breathing solitons can be more stable against certain experimental perturbations than rigid solitons or even noninteracting wave packets.

  6. Structural change of vortex patterns in anisotropic Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Lo Gullo, N.; Busch, Th.; Paternostro, M.

    2011-05-01

    We study the changes in the spatial distribution of vortices in a rotating Bose-Einstein condensate due to an increasing eccentricity of the trapping potential. By breaking the rotational symmetry, the vortex system undergoes a rich variety of structural changes, including the formation of zigzag and linear configurations. These spatial rearrangements are well signaled by the change in the behavior of the vortex-pattern eigenmodes against the eccentricity parameter. This behavior allows to actively control the distribution of vorticity in many-body systems and opens the possibility of studying interactions between quantum vortices over a large range of parameters.

  7. Fragmented Superradiance of a Bose-Einstein Condensate in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Lode, Axel U. J.; Bruder, Christoph

    2017-01-01

    The Dicke model and the superradiance of two-level systems in a radiation field have many applications. Recently, a Dicke quantum phase transition has been realized with a Bose-Einstein condensate in a cavity. We numerically solve the many-body Schrödinger equation and study correlations in the ground state of interacting bosons in a cavity as a function of the strength of a driving laser. Beyond a critical strength, the bosons occupy multiple modes macroscopically while remaining superradiant. This fragmented superradiance can be detected by analyzing the variance of single-shot measurements.

  8. Dynamics of a Cold Trapped Ion in a Bose-Einstein Condensate

    SciTech Connect

    Schmid, Stefan; Haerter, Arne; Denschlag, Johannes Hecker

    2010-09-24

    We investigate the interaction of a laser-cooled trapped ion (Ba{sup +} or Rb{sup +}) with an optically confined {sup 87}Rb Bose-Einstein condensate. The system features interesting dynamics of the ion and the atom cloud as determined by their collisions and their motion in their respective traps. Elastic as well as inelastic processes are observed and their respective cross sections are determined. We demonstrate that a single ion can be used to probe the density profile of an ultracold atom cloud.

  9. Strong charge-transfer excitonic effects and the Bose-Einstein exciton condensate in graphane.

    PubMed

    Cudazzo, Pierluigi; Attaccalite, Claudio; Tokatly, Ilya V; Rubio, Angel

    2010-06-04

    Using first principles many-body theory methods (GW+Bethe-Salpeter equation) we demonstrate that the optical properties of graphane are dominated by localized charge-transfer excitations governed by enhanced electron correlations in a two-dimensional dielectric medium. Strong electron-hole interaction leads to the appearance of small radius bound excitons with spatially separated electron and hole, which are localized out of plane and in plane, respectively. The presence of such bound excitons opens the path towards an excitonic Bose-Einstein condensate in graphane that can be observed experimentally.

  10. Spontaneous spin bifurcations in a Bose-Einstein condensate of indirect excitons

    NASA Astrophysics Data System (ADS)

    Liu, T.; Liew, T. C. H.

    2017-08-01

    In this paper, we theoretically study the spin dynamics of a spatially trapped Bose-Einstein condensate of indirect excitons (IXs). A spontaneous parity-symmetry breaking spin bifurcation for bright excitons is reported under non-resonant linearly polarized pumping. Above a certain pumping amplitude, condensation for bright excitons spontaneously and stochastically adopts one of two spin-polarized configurations Sz depending on initial occupations. This phenomenon of spontaneous spin bifurcations is attributed to the small energy splitting and difference in dissipation rates between bright and dark excitons in IX systems. The considered systems thus have potential applications in spin memories, spin switches and to simulate spin interactions in condensed lattices.

  11. Low Energy Excitations of a Bose-Einstein Condensate: A Time-Dependent Variational Analysis

    SciTech Connect

    Perez-Garcia, V.M.; Michinel, H.; Cirac, J.; Lewenstein, M.; Zoller, P. ||||

    1996-12-01

    We solve the time-dependent Gross-Pitaevskii equation by a variational ansatz to calculate the excitation spectrum of a Bose-Einstein condensate in a trap. The trial wave function is a Gaussian which allows an essentially analytical treatment of the problem. Our results reproduce numerical calculations over the whole range from small to large particle numbers, and agree exactly with the Stringari results in the strong interaction limit. Excellent agreement is obtained with the recent JILA experiment and predictions for the negative scattering length case are also made. {copyright} {ital 1996 The American Physical Society.}

  12. Sonic horizon formation for oscillating Bose-Einstein condensates in isotropic harmonic potential.

    PubMed

    Wang, Ying; Zhou, Yu; Zhou, Shuyu

    2016-12-06

    We study the sonic horizon phenomena of the oscillating Bose-Einstein condensates in isotropic harmonic potential. Based on the Gross-Pitaevskii equation model and variational method, we derive the original analytical formula for the criteria and lifetime of the formation of the sonic horizon, demonstrating pictorially the interaction parameter dependence for the occur- rence of the sonic horizon and damping effect of the system distribution width. Our analytical results corroborate quantitatively the particular features of the sonic horizon reported in previous numerical study.

  13. Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding

    NASA Astrophysics Data System (ADS)

    Burton, William Cody; Kennedy, Colin J.; Chung, Woo Chang; Vadia, Samarth; Chen, Wenlan; Ketterle, Wolfgang

    2016-12-01

    We demonstrate a new way to extend the coherence time of separated Bose-Einstein condensates that involves immersion into a superfluid bath. When both the system and the bath have similar scattering lengths, immersion in a superfluid bath cancels out inhomogeneous potentials either imposed by external fields or inherent in density fluctuations due to atomic shot noise. This effect, which we call superfluid shielding, allows for coherence lifetimes beyond the projection noise limit. We probe the coherence between separated condensates in different sites of an optical lattice by monitoring the contrast and decay of Bloch oscillations. Our technique demonstrates a new way that interactions can improve the performance of quantum devices.

  14. Spatial Landau-Zener-Stueckelberg interference in spinor Bose-Einstein condensates

    SciTech Connect

    Zhang, J.-N.; Sun, C.-P.; Yi, S.; Nori, Franco

    2011-03-15

    We investigate the Stueckelberg oscillations of a spin-1 Bose-Einstein condensate subject to a spatially inhomogeneous transverse magnetic field and a periodic longitudinal field. We show that the time-domain Stueckelberg oscillations result in modulations in the density profiles of all spin components due to the spatial inhomogeneity of the transverse field. This phenomenon represents the Landau-Zener-Stueckelberg interference in the space domain. Since the magnetic dipole-dipole interaction between spin-1 atoms induces an inhomogeneous effective magnetic field, interference fringes also appear if a dipolar spinor condensate is driven periodically. We also point out some potential applications of this spatial Landau-Zener-Stuekelberg interference.

  15. Quantum chaos of bogoliubov waves for a bose-einstein condensate in stadium billiards.

    PubMed

    Zhang, Chuanwei; Liu, Jie; Raizen, Mark G; Niu, Qian

    2004-08-13

    We investigate the possibility of quantum (or wave) chaos for the Bogoliubov excitations of a Bose-Einstein condensate in billiards. Because of the mean field interaction in the condensate, the Bogoliubov excitations are very different from the single particle excitations in a noninteracting system. Nevertheless, we predict that the statistical distribution of level spacings is unchanged by mapping the non-Hermitian Bogoliubov operator to a real symmetric matrix. We numerically test our prediction by using a phase shift method for calculating the excitation energies.

  16. Modified uncertainty principle from the free expansion of a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Castellanos, Elías; Escamilla-Rivera, Celia

    2017-01-01

    In this paper, we present a theoretical and numerical analysis of the free expansion of a Bose-Einstein condensate, where we assume that the single particle energy spectrum is deformed due to a possible quantum structure of spacetime. Also, we consider the presence of interparticle interactions in order to study more realistic and specific scenarios. The modified free velocity expansion of the condensate leads in a natural way to a modification of the uncertainty principle, which allows us to investigate some possible features of the Planck scale regime in low-energy earth-based experiments.

  17. Tunable spin-orbit-coupled Bose-Einstein condensates in deep optical lattices

    NASA Astrophysics Data System (ADS)

    Salerno, M.; Abdullaev, F. Kh.; Gammal, A.; Tomio, Lauro

    2016-10-01

    Binary mixtures of Bose-Einstein condensates (BECs) trapped in deep optical lattices and subjected to equal contributions of Rashba and Dresselhaus spin-orbit coupling (SOC) are investigated in the presence of a periodic time modulation of the Zeeman field. SOC tunability is explicitly demonstrated by adopting a mean-field tight-binding model for the BEC mixture and by performing an averaging approach in the strong modulation limit. In this case, the system can be reduced to an unmodulated vector discrete nonlinear Schrödinger equation with a rescaled SOC tuning parameter α , which depends only on the ratio between amplitude and frequency of the applied Zeeman field. We consider the attractive interaction case and focus on the effect of the SOC tuning on the localized ground states. The dependence of the spectrum of the linear system on α has been analytically characterized. In particular, we show that extremal curves (ground and highest excited states) of the linear spectrum are continuous piecewise functions (together with their derivatives) of α , which consist of a finite number of decreasing band lobes joined by constant lines. This structure also remains in the presence of inter- and intra-species interactions, the nonlinearity mainly introducing a number of localized states in the band gaps. The stability of ground states in the presence of the modulating field has been demonstrated by real-time evolutions of the original (unaveraged) system. Localization properties of the ground state induced by the SOC tuning, and a parameter design for possible experimental observation, have also been discussed.

  18. Dynamics of dark-bright vector solitons in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Alotaibi, Majed O. D.; Carr, Lincoln D.

    2017-07-01

    We analyze the dynamics of two-component vector solitons, namely, dark-bright solitons, via the variational approximation in Bose-Einstein condensates. The system is described by a vector nonlinear Schrödinger equation appropriate to multicomponent Bose-Einstein condensates. The variational approximation is based on a hyperbolic tangent (hyperbolic secant) for the dark (bright) component, which leads to a system of coupled ordinary differential equations for the evolution of the ansatz parameters. We obtain the oscillation dynamics of two-component dark-bright solitons. Analytical calculations are performed for same-width components in the vector soliton, and numerical calculations extend the results to arbitrary widths. We calculate the binding energy of the system and find it to be proportional to the intercomponent coupling interaction and numerically demonstrate the breakup or unbinding of a dark-bright soliton. Our calculations explore observable eigenmodes, namely, the internal oscillation eigenmode and the Goldstone eigenmode. We find analytically that the number of atoms in the bright component is required to be less than the number of atoms displaced by the dark soliton in the other component in order to find the internal oscillation eigenmode of the vector soliton and support the existence of the dark-bright soliton. This outcome is confirmed by numerical results. Numerically, we find that the oscillation frequency is amplitude independent. For dark-bright solitons in 87Rb we find that the oscillation frequency range is 90 to 405 Hz and therefore observable in multicomponent Bose-Einstein condensate experiments.

  19. Constraints on Bose-Einstein-condensed axion dark matter from the Hi nearby galaxy survey data

    NASA Astrophysics Data System (ADS)

    Li, Ming-Hua; Li, Zhi-Bing

    2014-05-01

    One of the leading candidates for dark matter is the axion or axionlike particle in the form of a Bose-Einstein condensate (BEC). In this paper, we present an analysis of 17 high-resolution galactic rotation curves from the Hi nearby galaxy survey (THINGS) data [F. Walter et al., Astron. J. 136, 2563 (2008)] in the context of the axionic Bose-Einstein condensed dark matter model. Assuming a repulsive two-body interaction, we solve the nonrelativistic Gross-Pitaevskii equation for N gravitationally trapped bosons in the Thomas-Fermi approximation. We obtain the maximum possible radius R and the mass profile M(r) of a dilute axionic Bose-Einstein condensed gas cloud. A standard least- χ2 method is employed to find the best-fit values of the total mass M of the axion BEC and its radius R. The local mass density of BEC axion dark matter is ρa ≃0.02 GeV /cm3, which agrees with that presented by Beck [C. Beck, Phys. Rev. Lett. 111, 231801 (2013)]. The axion mass ma we obtain depends not only on the best-fit value of R, but also on the s-wave scattering length a (ma∝a1/3). The transition temperature Ta of an axion BEC on galactic scales is also estimated. Comparing the calculated Ta with the ambient temperature of galaxies and galaxy clusters implies that a ˜10-3 fm. The corresponding axion mass is ma≃0.58 meV. We compare our results with others.

  20. Dynamics of matter-wave solitons in Bose-Einstein condensates with time-dependent scattering length and complex potentials

    NASA Astrophysics Data System (ADS)

    Kengne, Emmanuel; Shehou, Abdourahman; Lakhssassi, Ahmed

    2016-03-01

    We investigate the dynamics of matter-wave solitons in the one-dimensional (1-D) Gross-Pitaevskii (GP) equation describing Bose-Einstein condensates (BECs) with time-dependent scattering length in varying trapping potentials with feeding/loss term. By performing a modified lens-type transformation, we reduce the GP equation into a classical nonlinear Schrödinger (NLS) equation with distributed coefficients and find its integrable condition. Under the integrable condition, we apply the generalized Jacobian elliptic function method (GJEFM) and present exact analytical solutions which describe the propagation of a bright and dark solitons in BECs. Their stability is examined using analytic method. The obtained exact solutions show that the amplitude of bright and dark solitons depends on the scattering length, while their motion and the total number of BEC atoms depend on the external trapping potential. Our results also shown that the loss of atoms can dominate the aggregation of atoms by the attractive interaction, and thus the peak density can decrease in time despite that the strength of the attractive interaction is increased.

  1. Casimir-Like Force Arising from Quantum Fluctuations in a Slowly Moving Dilute Bose-Einstein Condensate

    SciTech Connect

    Roberts, D.C.; Pomeau, Y.

    2005-09-30

    We calculate a force due to zero-temperature quantum fluctuations on a stationary object in a moving superfluid flow. We model the object by a localized potential varying only in the flow direction and model the flow by a three-dimensional weakly interacting Bose-Einstein condensate at zero temperature. We show that this force exists for any arbitrarily small flow velocity and discuss the implications for the stability of superfluid flow.

  2. Gibbons-Hawking effect in the sonic de Sitter space-time of an expanding Bose-Einstein-condensed gas.

    PubMed

    Fedichev, Petr O; Fischer, Uwe R

    2003-12-12

    We propose an experimental scheme to observe the Gibbons-Hawking effect in the acoustic analog of a (1+1)-dimensional de Sitter universe, produced in an expanding, cigar-shaped Bose-Einstein condensate. It is shown that a two-level system created at the center of the trap, an atomic quantum dot interacting with phonons, observes a thermal Bose distribution at the de Sitter temperature.

  3. Theory of cold atoms: Bose-Einstein statistics

    NASA Astrophysics Data System (ADS)

    Yukalov, V. I.

    2016-06-01

    This tutorial is the continuation of the previous tutorial part, published in (2013 Laser Phys. 23 062001), where the basic mathematical techniques required for an accurate description of cold atoms for both types of quantum statistics are expounded. In the present part, the specifics of the correct theoretical description of atoms obeying Bose-Einstein statistics are explained, including trapped Bose atoms. In the theory of systems exhibiting the phenomenon of Bose-Einstein condensation, there exists a number of delicate mathematical points, whose misunderstanding often results in principally wrong conclusions. This is why the consideration in the present tutorial is sufficiently detailed in order that the reader could clearly understand the underlying mathematics and would avoid confusions.

  4. Bose-Einstein condensates and scalar fields; exploring the similitudes

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Macías, A.; Núñez, D.

    2014-01-01

    We analyze the the remarkable analogy between the classical Klein-Gordon equation for a test scalar field in a flat and also in a curved background, and the Gross-Pitaevskii equation for a Bose-Einstein condensate trapped by an external potential. We stress here that the solution associated with the Klein-Gordon equation (KG) in a flat space time has the same mathematical structure, under certain circumstances, to those obtained for the Gross-Pitaevskii equation, that is, a static soliton solution. Additionally, Thomas-Fermi approximation is applied to the 3-dimensional version of this equation, in order to calculate some thermodynamical properties of the system in curved a space-time back ground. Finally, we stress the fact that a gravitational background provides, in some cases, a kind of confining potential for the scalar field, allowing us to remarks even more the possible connection between scalar fields and the phenomenon of Bose-Einstein condensation.

  5. Bose-Einstein condensation on closed Robertson-Walker spacetimes

    NASA Astrophysics Data System (ADS)

    Trucks, M.

    1998-12-01

    In this letter we summarize our analysis of Bose-Einstein condensation on closed Robertson-Walker spacetimes. In a previous work we defined an adiabatic KMS state on the Weyl-algebra of the free massive Klein-Gordon field [M. Trucks, M. Keyl, Phys. Lett. B 399 (1997) 223, M. Trucks, Commun. Math. Phys. 197 (1998) 387]. This state describes a free Bose gas on Robertson-Walker spacetimes. We use this state to analyze the possibility of Bose-Einstein condensation on closed Robertson-Walker spacetimes. We take into account the effects due to the finiteness of the spatial volume and show that they are not relevant in the early universe. Furthermore we show that a critical radius can be defined. The condensate disappears above the critical radius.

  6. Vortex Pump for Dilute Bose-Einstein Condensates

    SciTech Connect

    Moettoenen, Mikko; Pietilae, Ville; Virtanen, Sami M. M.

    2007-12-21

    The formation of vortices by topological phase engineering has been realized experimentally to create the first two- and four-quantum vortices in dilute atomic Bose-Einstein condensates. We consider a similar system, but in addition to the Ioffe-Pritchard magnetic trap we employ an additional hexapole field. By controlling cyclically the strengths of these magnetic fields, we show that a fixed amount of vorticity can be added to the condensate in each cycle. In an adiabatic operation of this vortex pump, the appearance of vortices into the condensate is interpreted as the accumulation of a local Berry phase. Our design can be used as an experimentally realizable vortex source for possible vortex-based applications of dilute Bose-Einstein condensates.

  7. Breakdown of Bose-Einstein Distribution in Photonic Crystals

    PubMed Central

    Lo, Ping-Yuan; Xiong, Heng-Na; Zhang, Wei-Min

    2015-01-01

    In the last two decades, considerable advances have been made in the investigation of nano-photonics in photonic crystals. Previous theoretical investigations of photon dynamics were carried out at zero temperature. Here, we investigate micro/nano cavity photonics in photonic crystals at finite temperature. Due to photonic-band-gap-induced localized long-lived photon dynamics, we discover that cavity photons in photonic crystals do not obey Bose-Einstein statistical distribution. Within the photonic band gap and in the vicinity of the band edge, cavity photons combine the long-lived non-Markovain dynamics with thermal fluctuations together to form photon states that memorize the initial cavity state information. As a result, Bose-Einstein distribution is completely broken down in these regimes, even if the thermal energy is larger or much larger than the cavity detuning energy. In this investigation, a crossover phenomenon from equilibrium to nonequilibrium steady states is also revealed. PMID:25822135

  8. Vortex pump for dilute bose-einstein condensates.

    PubMed

    Möttönen, Mikko; Pietilä, Ville; Virtanen, Sami M M

    2007-12-21

    The formation of vortices by topological phase engineering has been realized experimentally to create the first two- and four-quantum vortices in dilute atomic Bose-Einstein condensates. We consider a similar system, but in addition to the Ioffe-Pritchard magnetic trap we employ an additional hexapole field. By controlling cyclically the strengths of these magnetic fields, we show that a fixed amount of vorticity can be added to the condensate in each cycle. In an adiabatic operation of this vortex pump, the appearance of vortices into the condensate is interpreted as the accumulation of a local Berry phase. Our design can be used as an experimentally realizable vortex source for possible vortex-based applications of dilute Bose-Einstein condensates.

  9. Planck distribution of phonons in a Bose-Einstein condensate.

    PubMed

    Schley, R; Berkovitz, A; Rinott, S; Shammass, I; Blumkin, A; Steinhauer, J

    2013-08-02

    The Planck distribution of photons emitted by a blackbody led to the development of quantum theory. An analogous distribution of phonons should exist in a Bose-Einstein condensate. We observe this Planck distribution of thermal phonons in a 3D condensate. This observation provides an important confirmation of the basic nature of the condensate's quantized excitations. In contrast to the bunching effect, the density fluctuations are seen to increase with increasing temperature. This is due to the nonconservation of the number of phonons. In the case of rapid cooling, the phonon temperature is out of equilibrium with the surrounding thermal cloud. In this case, a Bose-Einstein condensate is not as cold as previously thought. These measurements are enabled by our in situ k-space technique.

  10. Breakdown of Bose-Einstein distribution in photonic crystals.

    PubMed

    Lo, Ping-Yuan; Xiong, Heng-Na; Zhang, Wei-Min

    2015-03-30

    In the last two decades, considerable advances have been made in the investigation of nano-photonics in photonic crystals. Previous theoretical investigations of photon dynamics were carried out at zero temperature. Here, we investigate micro/nano cavity photonics in photonic crystals at finite temperature. Due to photonic-band-gap-induced localized long-lived photon dynamics, we discover that cavity photons in photonic crystals do not obey Bose-Einstein statistical distribution. Within the photonic band gap and in the vicinity of the band edge, cavity photons combine the long-lived non-Markovain dynamics with thermal fluctuations together to form photon states that memorize the initial cavity state information. As a result, Bose-Einstein distribution is completely broken down in these regimes, even if the thermal energy is larger or much larger than the cavity detuning energy. In this investigation, a crossover phenomenon from equilibrium to nonequilibrium steady states is also revealed.

  11. Breakdown of Bose-Einstein Distribution in Photonic Crystals

    NASA Astrophysics Data System (ADS)

    Lo, Ping-Yuan; Xiong, Heng-Na; Zhang, Wei-Min

    2015-03-01

    In the last two decades, considerable advances have been made in the investigation of nano-photonics in photonic crystals. Previous theoretical investigations of photon dynamics were carried out at zero temperature. Here, we investigate micro/nano cavity photonics in photonic crystals at finite temperature. Due to photonic-band-gap-induced localized long-lived photon dynamics, we discover that cavity photons in photonic crystals do not obey Bose-Einstein statistical distribution. Within the photonic band gap and in the vicinity of the band edge, cavity photons combine the long-lived non-Markovain dynamics with thermal fluctuations together to form photon states that memorize the initial cavity state information. As a result, Bose-Einstein distribution is completely broken down in these regimes, even if the thermal energy is larger or much larger than the cavity detuning energy. In this investigation, a crossover phenomenon from equilibrium to nonequilibrium steady states is also revealed.

  12. Bose-Einstein condensation of pions in ultrarelativistic nucleus-nucleus collisions and the spectra of kaons

    SciTech Connect

    Kolomeitsev, E.E. |; Voskresensky, D.N.

    1995-12-01

    The properties of a pion gas that is formed in ultrarelativistic collisions of nuclei are studied in the Weinberg, model for {pi}{pi} interaction. The possible Bose-Einstein condensation of a dense n-gas is considered. The Green`s function and the spectrum of the overcondensate excitations are calculated. For a weak condensate, the results coincide with those obtained in the {lambda}{var_phi}{sup 4} model ({lambda} = const), while for a developed condensate there are significant differences. The properties of kaons are considered for temperatures below the critical temperature for Bose-Einstein pion condensation. It is shown that, in the presence of a condensate, the K-effective mass becomes substantially larger, while the K{sup +} effective mass becomes smaller. These features may manifest themselves in the observable momentum distributions of kaons. 16 refs., 4 figs.

  13. Bose-Einstein Condensation in the Relativistic Ideal Bose Gas

    SciTech Connect

    Grether, M.; Llano, M. de; Baker, George A. Jr.

    2007-11-16

    The Bose-Einstein condensation (BEC) critical temperature in a relativistic ideal Bose gas of identical bosons, with and without the antibosons expected to be pair-produced abundantly at sufficiently hot temperatures, is exactly calculated for all boson number densities, all boson point rest masses, and all temperatures. The Helmholtz free energy at the critical BEC temperature is lower with antibosons, thus implying that omitting antibosons always leads to the computation of a metastable state.

  14. Taming rogue waves in vector Bose-Einstein condensates.

    PubMed

    Vinayagam, P S; Radha, R; Porsezian, K

    2013-10-01

    Using gauge transformation method, we generate rogue waves for the two-component Bose-Einstein condensates (BECs) governed by the symmetric coupled Gross-Pitaevskii (GP) equations and study their dynamics. We also suggest a mechanism to tame the rogue waves either by manipulating the scattering length through Feshbach resonance or the trapping frequency, a phenomenon not witnessed in the domain of BECs, and we believe that these results may have wider ramifications in the management of rogons.

  15. Bose-Einstein Condensate in a Random Potential

    SciTech Connect

    Lye, J.E.; Fallani, L.; Fort, C.; Inguscio, M.; Modugno, M.; Wiersma, D.S.

    2005-08-12

    An optical speckle potential is used to investigate the static and dynamic properties of a Bose-Einstein condensate in the presence of disorder. With small levels of disorder, stripes are observed in the expanded density profile and strong damping of dipole and quadrupole oscillations is seen. Uncorrelated frequency shifts of the two modes are measured and are explained using a sum-rules approach and by the numerical solution of the Gross-Pitaevskii equation.

  16. Stable knots in the trapped Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Kai; Feng, Shiping; Yang, Shi-Jie

    2014-06-01

    The knot of the spin-texture is studied within the two-component Bose-Einstein condensates which are described by the nonlinear Gross-Pitaevskii equations. We start from the noninteracting equations including an axisymmetric harmonic trap to obtain an exact solution, which exhibits a nontrivial topological structure. The spin-texture is a knot with an integral Hopf invariant. The stability of the knot is verified by numerically evolving the nonlinear Gross-Pitaevskii equations along imaginary time.

  17. Bose-Einstein condensate in a random potential.

    PubMed

    Lye, J E; Fallani, L; Modugno, M; Wiersma, D S; Fort, C; Inguscio, M

    2005-08-12

    An optical speckle potential is used to investigate the static and dynamic properties of a Bose-Einstein condensate in the presence of disorder. With small levels of disorder, stripes are observed in the expanded density profile and strong damping of dipole and quadrupole oscillations is seen. Uncorrelated frequency shifts of the two modes are measured and are explained using a sum-rules approach and by the numerical solution of the Gross-Pitaevskii equation.

  18. Magnons as a Bose-Einstein Condensate in Nanocrystalline Gadolinium

    SciTech Connect

    Kaul, S. N.; Mathew, S. P.

    2011-06-17

    The recent observation [S. P. Mathew et al., J. Phys. Conf. Ser. 200, 072047 (2010)] of the anomalous softening of spin-wave modes at low temperatures in nanocrystalline gadolinium is interpreted as a Bose-Einstein condensation (BEC) of magnons. A self-consistent calculation, based on the BEC picture, is shown to closely reproduce the observed temperature variations of magnetization and specific heat at constant magnetic fields.

  19. Bose-Einstein condensation in the relativistic ideal Bose gas.

    PubMed

    Grether, M; de Llano, M; Baker, George A

    2007-11-16

    The Bose-Einstein condensation (BEC) critical temperature in a relativistic ideal Bose gas of identical bosons, with and without the antibosons expected to be pair-produced abundantly at sufficiently hot temperatures, is exactly calculated for all boson number densities, all boson point rest masses, and all temperatures. The Helmholtz free energy at the critical BEC temperature is lower with antibosons, thus implying that omitting antibosons always leads to the computation of a metastable state.

  20. Controlling chaos in the Bose-Einstein condensate

    SciTech Connect

    Cong Fuzhong Wang Zhixia; Hua Hongtu; Pang Shichun; Tong Shouyu

    2012-03-15

    The spatial structure of the Bose-Einstein condensate (BEC) is investigated and spatially chaotic distributions of the condensates are revealed. By means of changing the s-wave scattering length with a Feshbach resonance, the chaotic behavior can be well controlled to enter into periodicity. Numerical simulation shows that there are different periodic orbits according to different s-wave scattering lengths only if the Lyapunov exponent of the system is negative.

  1. Bose-Einstein condensation and free DKP field

    NASA Astrophysics Data System (ADS)

    Casana, R.; Fainberg, V. Ya.; Pimentel, B. M.; Valverde, J. S.

    2003-09-01

    The thermodynamical partition function of the Duffin-Kemmer-Petiau theory is evaluated using the imaginary-time formalism of quantum field theory at finite temperature and path integral methods. The DKP partition function displays two features: (i) full equivalence with the partition function for charged scalar particles and charged massive spin 1 particles; and (ii) the zero mode sector which is essential to reproduce the well-known relativistic Bose-Einstein condensation for both theories.

  2. Beliaev damping of quasiparticles in a Bose-Einstein condensate.

    PubMed

    Katz, N; Steinhauer, J; Ozeri, R; Davidson, N

    2002-11-25

    We report a measurement of the suppression of collisions of quasiparticles with ground state atoms within a Bose-Einstein condensate at low momentum. These collisions correspond to Beliaev damping of the excitations, in the previously unexplored regime of the continuous quasiparticle energy spectrum. We use a hydrodynamic simulation of the expansion dynamics, with the Beliaev damping cross section, in order to confirm the assumptions of our analysis.

  3. Inhibition of Coherence in Trapped Bose-Einstein Condensates

    SciTech Connect

    Imamoglu, A.; Lewenstein, M.

    1997-03-01

    We analyze the dependence of the collapse and revival of many-atom coherence of a trapped Bose-Einstein condensate on the trap potential, dimensionality of the gas, and atom number fluctuations. We show that in a class of experimentally relevant systems the collapse time vanishes in the limit of a large number of atoms, implying that the trapped Bose gas cannot sustain a well-defined quantum phase. {copyright} {ital 1997} {ital The American Physical Society}

  4. Localized modes in quasi-two-dimensional Bose-Einstein condensates with spin-orbit and Rabi couplings

    NASA Astrophysics Data System (ADS)

    Salasnich, Luca; Cardoso, Wesley B.; Malomed, Boris A.

    2014-09-01

    We consider a two-component pancake-shaped, i.e., effectively two-dimensional (2D), Bose-Einstein condensate coupled by the spin-orbit (SO) and Rabi terms. The SO coupling adopted here is of the mixed Rashba-Dresselhaus type. For this configuration, we derive a system of two 2D nonpolynomial Schrödinger equations (NPSEs), for both attractive and repulsive interatomic interactions. In the low- and high-density limits, the system amounts to previously known models, namely, the usual 2D Gross-Pitaevskii equation, or the Schrödinger equation with the nonlinearity of power 7/3. We present simple approximate localized solutions, obtained by treating the SO and Rabi terms as perturbations. Localized solutions of the full NPSE system are obtained in a numerical form. Remarkably, in the case of the attractive nonlinearity acting in free space (i.e., without any 2D trapping potential), we find parameter regions where the SO and Rabi couplings make 2D fundamental solitons dynamically stable.

  5. Particle-localized ground state of atom-molecule Bose-Einstein condensates in a double-well potential

    SciTech Connect

    Motohashi, Atsushi; Nikuni, Tetsuro

    2010-09-15

    We study the effect of atom-molecule internal tunneling on the ground state of atom-molecule Bose-Einstein condensates in a double-well potential. In the absence of internal tunneling between atomic and molecular states, the ground state is symmetric, which has equal-particle populations in two wells. From the linear stability analysis, we show that the symmetric stationary state becomes dynamically unstable at a certain value of the atom-molecule internal tunneling strength. Above the critical value of the internal tunneling strength, the ground state bifurcates to the particle-localized ground states. The origin of this transition can be attributed to the effective attractive interatomic interaction induced by the atom-molecule internal tunneling. This effective interaction is similar to that familiar in the context of BCS-BEC crossover in a Fermi gas with Feshbach resonance. Furthermore, we point out the possibility of reentrant transition in the case of the large detuning between the atomic and molecular states.

  6. Entanglement and entropy production in coupled single-mode Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Lovas, Izabella; Fortágh, József; Demler, Eugene; Zaránd, Gergely

    2017-08-01

    We investigate the time evolution of the entanglement entropy of coupled single-mode Bose-Einstein condensates in a double-well potential at T =0 temperature by combining numerical results with analytical approximations. We find that the coherent oscillations of the condensates result in entropy oscillations on the top of a linear entropy generation at short time scales. Due to dephasing, the entropy eventually saturates to a stationary value, in spite of the lack of equilibration. We show that this long-time limit of the entropy reflects the semiclassical dynamics of the system, revealing the self-trapping phase transition of the condensates at large interaction strength by a sudden entropy jump. We compare the stationary limit of the entropy to the prediction of a classical microcanonical ensemble and find surprisingly good agreement in spite of the nonequilibrium state of the system. Our predictions should be experimentally observable on a Bose-Einstein condensate in a double-well potential or on a two-component condensate with interstate coupling.

  7. Four-wave mixing in Bose-Einstein condensate systems with multiple spin states

    SciTech Connect

    Burke, J.P. Jr.; Julienne, P. S.; Williams, C.J.; Band, Y.B.; Trippenbach, M.

    2004-09-01

    We calculate the four-wave mixing (FWM) in a Bose-Einstein condensate system having multiple spin wave packets that are initially overlapping in physical space, but have nonvanishing relative momentum that causes them to recede from one another. Three receding condensate atom wave packets can result in production of a fourth wave packet by the process of FWM due to atom-atom interactions. We consider cases where the four final wave packets are composed of one, two, three, and four different internal spin components. FWM with one or two-spin state wave packets is much stronger than three- or four-spin state FWM, wherein two of the coherent moving Bose-Einstein condensate wave packets form a spin-polarization grating that rotates the spin projection of the third wave into that of the fourth diffracted wave (as opposed to the one- or two-spin state case where a regular density grating is responsible for the diffraction). Calculations of FWM for {sup 87}Rb and {sup 23}Na condensate systems are presented.

  8. Bose-Einstein condensation of spin wave quanta at room temperature.

    PubMed

    Dzyapko, O; Demidov, V E; Melkov, G A; Demokritov, S O

    2011-09-28

    Spin waves are delocalized excitations of magnetic media that mainly determine their magnetic dynamics and thermodynamics at temperatures far below the critical one. The quantum-mechanical counterparts of spin waves are magnons, which can be considered as a gas of weakly interacting bosonic quasi-particles. Here, we discuss the room-temperature kinetics and thermodynamics of the magnon gas in yttrium iron garnet films driven by parametric microwave pumping. We show that for high enough pumping powers, the thermalization of the driven gas results in a quasi-equilibrium state described by Bose-Einstein statistics with a non-zero chemical potential. Further increases of the pumping power cause a Bose-Einstein condensation documented by an observation of the magnon accumulation at the lowest energy level. Using the sensitivity of the Brillouin light scattering spectroscopy to the degree of coherence of the scattering magnons, we confirm the spontaneous emergence of coherence of the magnons accumulated at the bottom of the spectrum, occurring if their density exceeds a critical value.

  9. Dynamics and stability of stationary states for the spin-1 Bose-Einstein condensates in a standing light wave

    NASA Astrophysics Data System (ADS)

    Wang, Deng-Shan; Han, Wei; Shi, Yuren; Li, Zaidong; Liu, Wu-Ming

    2016-07-01

    The spin-1 Bose-Einstein condensates trapped in a standing light wave can be described by three coupled Gross-Pitaevskii equations with a periodic potential. In this paper, nine families of stationary solutions without phase structures in the form of Jacobi elliptic functions are proposed, and their stabilities are analyzed by both linear stability analysis and dynamical evolutions. Taking the ferromagnetic 87Rb atoms and antiferromagnetic (polar) 23Na atoms as examples, we investigate the stability regions of the nine stationary solutions, which are given in term of elliptic modulus k. It is shown that for the same stationary solution the stability regions of condensates with antiferromagnetic (polar) spin-dependent interactions are larger than that of the condensates with ferromagnetic ones. The dn-dn-dn stationary solution is the most stable solution among the nine families of stationary solutions. Moreover, in the same standing light wave, the spin-1 Bose-Einstein condensates are more stable than the scalar Bose-Einstein condensate.

  10. Manipulating nonclassical quantum statistical properties of light field by an f-deformed Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Darareh, M. Davoudi; Naderi, M. H.; Soltanolkotabi, M.

    2009-12-01

    We consider the interaction between an f-deformed Bose-Einstein condensate and a single-mode quantized light field. By using the Gardiner's phonon operators, we find that there exists a natural deformation in the model which modifies the Bogoliubov approximation under the condition of large but finite number of particles in condensate. This approach introduces an intrinsically deformed Bose-Einstein condensate, where the deformation parameter, well-defined by the particle number N in condensate, controls the strength of the associated nonlinearity. By introducing the deformed Gardiner's phonon operators we modify the very dilute-gas approximation through including atomic collisions in condensate. The rate of atomic collisions κ, as a new deformation parameter in the deformed Bose-Einstein condensate, controls the nonlinearity related to the atomic collisions. We show that by controlling the nonlinearities in the f-deformed atomic condensate through the two atomic parameters N and κ, it is possible to generate and manipulate the nonclassical quantum statistical properties of radiation field, such as, the sub-Poissonian photon statistics and quadrature squeezing. Also, it is possible to control the collapses and revivals phenomena in the average number of photons by atomic parameters N and κ.

  11. Engineered potentials in ultracold Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Campbell, Daniel L.

    Bose-Einstein condensates (BECs) are a recent addition to the portfolio of quantum materials some of which have profound commercial and military applications e.g., superconductors, superfluids and light emitting diodes. BECs exist in the lowest motional modes of a trap and have the lowest temperatures achieved by mankind. With full control over the shape of the trap the experimentalist may explore an extremely diverse set of Hamiltonians which may be altered mid-experiment. These properties are particularly suited for realizing novel quantum systems. This thesis explores interaction-driven domain formation and the subsequent domain coarsening for two immiscible BEC components. Because quantum coherences associated with interactions in BECs can be derived from low energy scattering theory we compare our experimental results to both a careful simulation (performed by Brandon Anderson) and an analytical prediction. This result very carefully explores the question of how a metastable system relaxes at the extreme limit of low temperature. We also explore spin-orbit coupling (SOC) of a BEC which links the linear and discrete momentum transferable by two counterpropagating ''Raman'' lasers that resonantly couple the ground electronic states of our BECs. SOC is used similarly in condensed matter systems to describe coupling between charge carrier spin and crystal momentum and is a necessary component of the quantum spin Hall effect and topological insulators. SOC links the linear and discrete momentum transferable by two counterpropagating ''Raman'' lasers and a subset of the ground electronic states of our BEC. The phases of an effective 2-spin component spin-orbit coupling (SOC) in a spin-1 BEC are described in Lin et al. (2011). We measure the phase transition between two phases of a spin-1 BEC with SOC which cannot be mimicked by a spin-1/2 system. The order parameter that describes transitions between these two phases is insensitive to magnetic field fluctuations. I

  12. Dynamic chaos and stability of a weakly open Bose-Einstein condensate in a double-well trap.

    PubMed

    Luo, Xiaobing; Hai, Wenhua

    2005-09-01

    We investigate the dynamics of a weakly open Bose-Einstein condensate with attractive interaction in a magneto-optical double-well trap. A set of time-dependent ordinary differential equations describing the complex dynamics are derived by using a two-mode approximation. The stability of the stationary solution is analyzed and some stability regions on the parameter space are displayed. In the symmetric well case, the numerical calculations reveal that by adjusting the feeding from the nonequilibrium thermal cloud or the two-body dissipation rate, the system could transit among the periodic motions, chaotic self-trapping states of the Lorenz model, and the steady states with the zero relative atomic population or with the macroscopic quantum self-trapping (MQST). In the asymmetric well case, we find the periodic orbit being a stable two-sided limited cycle with MQST. The results are in good agreement with that of the direct numerical simulations to the Gross-Pitaevskii equation.

  13. Dynamic chaos and stability of a weakly open Bose-Einstein condensate in a double-well trap

    SciTech Connect

    Luo Xiaobing; Hai Wenhua

    2005-09-01

    We investigate the dynamics of a weakly open Bose-Einstein condensate with attractive interaction in a magneto-optical double-well trap. A set of time-dependent ordinary differential equations describing the complex dynamics are derived by using a two-mode approximation. The stability of the stationary solution is analyzed and some stability regions on the parameter space are displayed. In the symmetric well case, the numerical calculations reveal that by adjusting the feeding from the nonequilibrium thermal cloud or the two-body dissipation rate, the system could transit among the periodic motions, chaotic self-trapping states of the Lorenz model, and the steady states with the zero relative atomic population or with the macroscopic quantum self-trapping (MQST). In the asymmetric well case, we find the periodic orbit being a stable two-sided limited cycle with MQST. The results are in good agreement with that of the direct numerical simulations to the Gross-Pitaevskii equation.

  14. Generalized Bose-Einstein condensation in superconductivity and superfluidity

    NASA Astrophysics Data System (ADS)

    Llano, M. de

    2008-03-01

    Unification of the Bardeen, Cooper and Schrieffer (BCS) and the Bose-Einstein condensation (BEC) theories is surveyed in terms of a generalized BEC (GBEC) finite-temperature statistical formalism. A vital distinction is that Cooper pairs (CPs) are true bosons that may suffer a BEC since they obey BE statistics, in contrast with BCS pairs that are "hard-core bosons" at best. A second crucial ingredient is the explicit presence of hole-pairs (2h) alongside the usual electron-pairs (2e). A third critical element (particularly in 2D where ordinary BEC does not occur) is the linear dispersion relation of CPs in leading order in the center-of-mass momentum (CMM) power-series expansion of the CP energy. The GBEC theory reduces in limiting cases to all five continuum (as opposed to "spin") statistical theories of superconductivity, from BCS on one extreme to the BEC theory on the other, as well as to the BCS-Bose "crossover" picture and the 1989 Friedberg-Lee BEC theory. It accounts for 2e- and 2h-CPs in arbitrary proportions while BCS theory can be deduced from the GBEC theory but allows only equal (50%-50%) BE condensed-mixtures of both kinds of CPs. As it yields the precise BCS gap equation for all temperatures as well as the precise BCS zero-temperature condensation energy for all couplings, it suggests that the BCS condensate is a BE condensate of a ternary mixture of kinematically independent unpaired electrons coexisting with equally proportioned weakly-bound zero-CMM 2e- and 2h-CPs. Without abandoning the electron-phonon mechanism in moderately weak coupling, and fortuituously insensitive to the BF interactions, the GBEC theory suffices to reproduce the unusually high values of Tc (in units of the Fermi temperature TF) of 0.01-0.05 empirically found in the so-called "exotic" superconductors of the Uemura plot, including cuprates, in contrast to the low values of Tc/TF⩽10-3 roughly reproduced by BCS theory for conventional (mostly elemental) superconductors.

  15. Generalized Bose-Einstein condensation in superconductivity and superfluidity

    SciTech Connect

    Llano, M. de

    2008-03-20

    Unification of the Bardeen, Cooper and Schrieffer (BCS) and the Bose-Einstein condensation (BEC) theories is surveyed in terms of a generalized BEC (GBEC) finite-temperature statistical formalism. A vital distinction is that Cooper pairs (CPs) are true bosons that may suffer a BEC since they obey BE statistics, in contrast with BCS pairs that are 'hard-core bosons' at best. A second crucial ingredient is the explicit presence of hole-pairs (2h) alongside the usual electron-pairs (2e). A third critical element (particularly in 2D where ordinary BEC does not occur) is the linear dispersion relation of CPs in leading order in the center-of-mass momentum (CMM) power-series expansion of the CP energy. The GBEC theory reduces in limiting cases to all five continuum (as opposed to 'spin') statistical theories of superconductivity, from BCS on one extreme to the BEC theory on the other, as well as to the BCS-Bose 'crossover' picture and the 1989 Friedberg-Lee BEC theory. It accounts for 2e- and 2h-CPs in arbitrary proportions while BCS theory can be deduced from the GBEC theory but allows only equal (50%-50%) BE condensed-mixtures of both kinds of CPs. As it yields the precise BCS gap equation for all temperatures as well as the precise BCS zero-temperature condensation energy for all couplings, it suggests that the BCS condensate is a BE condensate of a ternary mixture of kinematically independent unpaired electrons coexisting with equally proportioned weakly-bound zero-CMM 2e- and 2h-CPs. Without abandoning the electron-phonon mechanism in moderately weak coupling, and fortuituously insensitive to the BF interactions, the GBEC theory suffices to reproduce the unusually high values of T{sub c} (in units of the Fermi temperature T{sub F}) of 0.01-0.05 empirically found in the so-called 'exotic' superconductors of the Uemura plot, including cuprates, in contrast to the low values of T{sub c}/T{sub F}{<=}10{sup -3} roughly reproduced by BCS theory for conventional (mostly

  16. Magnon Bose-Einstein condensation and spin superfluidity

    NASA Astrophysics Data System (ADS)

    Bunkov, Yuriy M.; Volovik, Grigory E.

    2010-04-01

    Bose-Einstein condensation (BEC) is a quantum phenomenon of formation of a collective quantum state in which a macroscopic number of particles occupy the lowest energy state and thus is governed by a single wavefunction. Here we highlight the BEC in a magnetic subsystem—the BEC of magnons, elementary magnetic excitations. The magnon BEC is manifested as the spontaneously emerging state of the precessing spins, in which all spins precess with the same frequency and phase even in an inhomogeneous magnetic field. The coherent spin precession was observed first in superfluid 3He-B and this domain was called the homogeneously precessing domain (HPD). The main feature of the HPD is the induction decay signal, which ranges over many orders of magnitude longer than is prescribed by the inhomogeneity of magnetic field. This means that spins precess not with a local Larmor frequency, but coherently with a common frequency and phase. This BEC can also be created and stabilized by continuous NMR pumping. In this case the NMR frequency plays the role of a magnon chemical potential, which determines the density of the magnon condensate. The interference between two condensates has also been demonstrated. It was shown that HPD exhibits all the properties of spin superfluidity. The main property is the existence of a spin supercurrent. This spin supercurrent flows separately from the mass current. Transfer of magnetization by the spin supercurrent by a distance of more than 1 cm has been observed. Also related phenomena have been observed: the spin current Josephson effect; the phase-slip processes at the critical current; and the spin current vortex—a topological defect which is the analog of a quantized vortex in superfluids and of an Abrikosov vortex in superconductors; and so on. It is important to mention that the spin supercurrent is a magnetic phenomenon, which is not directly related to the mass superfluidity of 3He: it is the consequence of a specific

  17. Vector solitons in nearly one-dimensional Bose-Einstein condensates

    SciTech Connect

    Salasnich, Luca; Malomed, Boris A.

    2006-11-15

    We derive a system of nonpolynomial Schroedinger equations for one-dimensional wave functions of two components in a binary self-attractive Bose-Einstein condensate loaded in a cigar-shaped trap. The system is obtained by means of the variational approximation, starting from the coupled three-dimensional (3D) Gross-Pitaevskii equations and assuming, as usual, the factorization of 3D wave functions. The system can be obtained in a tractable form under a natural condition of symmetry between the two species. A family of vector (two-component) soliton solutions is constructed. Collisions between orthogonal solitons (ones belonging to the different components) are investigated by means of simulations. The collisions are essentially inelastic. They result in strong excitation of intrinsic vibrations in the solitons, and create a small orthogonal component ('shadow') in each colliding soliton. The collision may initiate collapse, which depends on the mass and velocities of the solitons.

  18. Delayed collapses of Bose-Einstein condensates in relation to anti-de Sitter gravity

    NASA Astrophysics Data System (ADS)

    Biasi, Anxo F.; Mas, Javier; Paredes, Angel

    2017-03-01

    We numerically investigate spherically symmetric collapses in the Gross-Pitaevskii equation with attractive nonlinearity in a harmonic potential. Even below threshold for direct collapse, the wave function bounces off from the origin and may eventually become singular after a number of oscillations in the trapping potential. This is reminiscent of the evolution of Einstein gravity sourced by a scalar field in anti de Sitter space where collapse corresponds to black-hole formation. We carefully examine the long time evolution of the wave function for continuous families of initial states in order to sharpen out this qualitative coincidence which may bring new insights in both directions. On the one hand, we comment on possible implications for the so-called Bosenova collapses in cold atom Bose-Einstein condensates. On the other hand, Gross-Pitaevskii provides a toy model to study the relevance of either the resonance conditions or the nonlinearity for the problem of anti de Sitter instability.

  19. Delayed collapses of Bose-Einstein condensates in relation to anti-de Sitter gravity.

    PubMed

    Biasi, Anxo F; Mas, Javier; Paredes, Angel

    2017-03-01

    We numerically investigate spherically symmetric collapses in the Gross-Pitaevskii equation with attractive nonlinearity in a harmonic potential. Even below threshold for direct collapse, the wave function bounces off from the origin and may eventually become singular after a number of oscillations in the trapping potential. This is reminiscent of the evolution of Einstein gravity sourced by a scalar field in anti de Sitter space where collapse corresponds to black-hole formation. We carefully examine the long time evolution of the wave function for continuous families of initial states in order to sharpen out this qualitative coincidence which may bring new insights in both directions. On the one hand, we comment on possible implications for the so-called Bosenova collapses in cold atom Bose-Einstein condensates. On the other hand, Gross-Pitaevskii provides a toy model to study the relevance of either the resonance conditions or the nonlinearity for the problem of anti de Sitter instability.

  20. Growth dynamics of a Bose-Einstein condensate in a dimple trap without cooling

    SciTech Connect

    Garrett, Michael C.; Davis, Matthew J.; Ratnapala, Adrian; Ooijen, Eikbert D. van; Vale, Christopher J.; Weegink, Kristian; Schnelle, Sebastian K.; Vainio, Otto; Heckenberg, Norman R.; Rubinsztein-Dunlop, Halina

    2011-01-15

    We study the formation of a Bose-Einstein condensate in a cigar-shaped three-dimensional harmonic trap, induced by the controlled addition of an attractive ''dimple'' potential along the weak axis. In this manner we are able to induce condensation without cooling due to a localized increase in the phase-space density. We perform a quantitative analysis of the thermodynamic transformation in both the sudden and adiabatic regimes for a range of dimple widths and depths. We find good agreement with equilibrium calculations based on self-consistent semiclassical Hartree-Fock theory describing the condensate and thermal cloud. We observe that there is an optimal dimple depth that results in a maximum in the condensate fraction. We also study the nonequilibrium dynamics of condensate formation in the sudden turn-on regime, finding good agreement for the observed time dependence of the condensate fraction with calculations based on quantum kinetic theory.

  1. Dynamical spin-density waves in a spin-orbit-coupled Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Li, Yan; Qu, Chunlei; Zhang, Yongsheng; Zhang, Chuanwei

    2015-07-01

    Synthetic spin-orbit (SO) coupling, an important ingredient for quantum simulation of many exotic condensed matter physics, has recently attracted considerable attention. The static and dynamic properties of a SO-coupled Bose-Einstein condensate (BEC) have been extensively studied in both theory and experiment. Here we numerically investigate the generation and propagation of a dynamical spin-density wave (SDW) in a SO-coupled BEC using a fast moving Gaussian-shaped barrier. We find that the SDW wavelength is sensitive to the barrier's velocity while varies slightly with the barrier's peak potential or width. We qualitatively explain the generation of SDW by considering a rectangular barrier in a one-dimensional system. Our results may motivate future experimental and theoretical investigations of rich dynamics in the SO-coupled BEC induced by a moving barrier.

  2. Dispersive Bottleneck Delaying Thermalization of Turbulent Bose-Einstein Condensates

    SciTech Connect

    Krstulovic, Giorgio; Brachet, Marc

    2011-03-18

    A new mechanism of thermalization involving a direct energy cascade is obtained in the truncated Gross-Pitaevskii dynamics. A long transient with partial thermalization at small scales is observed before the system reaches equilibrium. Vortices are found to disappear as a prelude to final thermalization. A bottleneck that produces spontaneous effective self-truncation and delays thermalization is characterized when large dispersive effects are present at the truncation wave number. Order of magnitude estimates indicate that self-truncation takes place in turbulent Bose-Einstein condensates. This effect should also be present in classical hydrodynamics and models of turbulence.

  3. Composite nature of hadrons and Bose-Einstein correlations

    NASA Astrophysics Data System (ADS)

    Bialas, A.

    2016-07-01

    I am reporting results of two papers, written together with W.Florkowski and K.Zalewski [1, 2], discussing the consequences of the observation [3] that, due to their composite nature and thus finite size, hadrons observed in the HBT measurements must be correlated in space-time. Using the blast-wave model [4] adjusted [1] to ALICE data on the measured HBT radii in pp collisions at 7 TeV [5], the full Bose-Einstein correlation functions in three direction (out, side, long) are evaluated. The results are presented together with some additional comments.

  4. Fidelity Decay in Trapped Bose-Einstein Condensates

    SciTech Connect

    Manfredi, G.; Hervieux, P.-A.

    2008-02-08

    The quantum coherence of a Bose-Einstein condensate is studied using the concept of quantum fidelity (Loschmidt echo). The condensate is confined in an elongated anharmonic trap and subjected to a small random potential such as that created by a laser speckle. Numerical experiments show that the quantum fidelity stays constant until a critical time, after which it drops abruptly over a single trap oscillation period. The critical time depends logarithmically on the number of condensed atoms and on the perturbation amplitude. This behavior may be observable by measuring the interference fringes of two condensates evolving in slightly different potentials.

  5. Observation of Solitonic Vortices in Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Donadello, Simone; Serafini, Simone; Tylutki, Marek; Pitaevskii, Lev P.; Dalfovo, Franco; Lamporesi, Giacomo; Ferrari, Gabriele

    2014-08-01

    We observe solitonic vortices in an atomic Bose-Einstein condensate (BEC) after free expansion. Clear signatures of the nature of such defects are the twisted planar density depletion around the vortex line, observed in absorption images, and the double dislocation in the interference pattern obtained through homodyne techniques. Both methods allow us to determine the sign of the quantized circulation. Experimental observations agree with numerical simulations. These solitonic vortices are the decay product of phase defects of the BEC order parameter spontaneously created after a rapid quench across the BEC transition in a cigar-shaped harmonic trap and are shown to have a very long lifetime.

  6. Nonlinear Rabi oscillations in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Rosanov, Nikolay N.

    2013-12-01

    For a Bose-Einstein condensate in a trap with oscillating barriers, in the resonance approximation, evolution equations are derived. Their analytical solution reveals the existence of two fundamentally different types of nonlinear conservative Rabi oscillations: (i) with periodic temporal variation of moduli and phase difference of levels’ amplitudes of probability, and (ii) with monotonic temporal variation of the phase difference. It is shown that the two types can be realized for the same parameters of the scheme, but for different initial conditions. Analytical predictions are confirmed by numerical solution to the Gross-Pitaevskii equation.

  7. Large magnetic storage ring for Bose-Einstein condensates

    SciTech Connect

    Arnold, A. S.; Garvie, C. S.; Riis, E.

    2006-04-15

    Cold atomic clouds and Bose-Einstein condensates have been stored in a 10 cm diameter vertically oriented magnetic ring. An azimuthal magnetic field enables low-loss propagation of atomic clouds over a total distance of 2 m, with a heating rate of less than 50 nK/s. The vertical geometry was used to split an atomic cloud into two counter-rotating clouds which were recombined after one revolution. The system will be ideal for studying condensate collisions and ultimately Sagnac interferometry.

  8. Winding up superfluid in a torus via Bose Einstein condensation

    SciTech Connect

    Das, Arnab; Sabbatini, Jacopo; Zurek, Wojciech H

    2010-12-16

    We simulate Bose-Einstein condensation at finite temperature in a ring employing stochastic Gross-Pitaevskii equation and show that cooling through the critical point can generate topologically stable quantized circulation of the newborn condensate around the ring. The resulting winding numbers exhibiting Gaussian distribution with dispersion following scaling behavior predicted by the Kibble-Zurek mechanism (KZM). This opens up possibilities for direct experimental study of the underlying phase transition and the basic principles of KZM extended to account for such circulations. We discuss the effect of inhomogeneity on the above phenomenon by considering the effect of tilting of the ring in the gravitational field.

  9. Rectified momentum transport for a kicked Bose-Einstein condensate.

    PubMed

    Sadgrove, Mark; Horikoshi, Munekazu; Sekimura, Tetsuo; Nakagawa, Ken'ichi

    2007-07-27

    We report the experimental observation of rectified momentum transport for a Bose-Einstein condensate kicked at the Talbot time (quantum resonance) by an optical standing wave. Atoms are initially prepared in a superposition of the 0 and -2hkl momentum states using an optical pi/2 pulse. By changing the relative phase of the superposed states, a momentum current in either direction along the standing wave may be produced. We offer an interpretation based on matter-wave interference, showing that the observed effect is uniquely quantum.

  10. Bose-Einstein condensation of relativistic Scalar Field Dark Matter

    SciTech Connect

    Urena-Lopez, L. Arturo

    2009-01-15

    Standard thermodynamical results of ideal Bose gases are used to study the possible formation of a cosmological Bose-Einstein condensate in Scalar Field Dark Matter models; the main hypothesis is that the boson particles were in thermal equilibrium in the early Universe. It is then shown that the only relevant case needs the presence of both particles and anti-particles, and that it corresponds to models in which the bosonic particle is very light. Contrary to common wisdom, the condensate should be a relativistic phenomenon. Some cosmological implications are discussed in turn.

  11. Rapidly rotating Bose-Einstein condensates in homogeneous traps

    SciTech Connect

    Correggi, M.; Rindler-Daller, T.; Yngvason, J.

    2007-10-15

    We extend the results of a previous paper on the Gross-Pitaevskii description of rotating Bose-Einstein condensates in two-dimensional traps to confining potentials of the form V(r)=r{sup s}, 2

  12. Quantum turbulence and correlations in Bose-Einstein condensate collisions

    NASA Astrophysics Data System (ADS)

    Norrie, A. A.; Ballagh, R. J.; Gardiner, C. W.

    2006-04-01

    We investigate numerically simulated collisions between experimentally realistic Bose-Einstein condensate wave packets, within a regime where highly populated scattering haloes are formed. The theoretical basis for this work is the truncated Wigner method, for which we present a detailed derivation, paying particular attention to its validity regime for colliding condensates. This paper is an extension of our previous Letter [A. A. Norrie, R. J. Ballagh, and C. W. Gardiner, Phys. Rev. Lett. 94, 040401 (2005)], and we investigate both single-trajectory solutions, which reveal the presence of quantum turbulence in the scattering halo, and ensembles of trajectories, which we use to calculate quantum-mechanical correlation functions of the field.

  13. Bose-Einstein condensation of dark matter axions.

    PubMed

    Sikivie, P; Yang, Q

    2009-09-11

    We show that cold dark matter axions thermalize and form a Bose-Einstein condensate (BEC). We obtain the axion state in a homogeneous and isotropic universe, and derive the equations governing small axion perturbations. Because they form a BEC, axions differ from ordinary cold dark matter in the nonlinear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles.

  14. Quasi-Nambu-Goldstone Modes in Bose-Einstein Condensates

    SciTech Connect

    Uchino, Shun; Kobayashi, Michikazu; Nitta, Muneto; Ueda, Masahito

    2010-12-03

    We show that quasi-Nambu-Goldstone (NG) modes, which play prominent roles in high energy physics but have been elusive experimentally, can be realized with atomic Bose-Einstein condensates. The quasi-NG modes emerge when the symmetry of a ground state is larger than that of the Hamiltonian. When they appear, the conventional vacuum manifold should be enlarged. Consequently, topological defects that are stable within the conventional vacuum manifold become unstable and decay by emitting the quasi-NG modes. Contrary to conventional wisdom, however, we show that the topological defects are stabilized by quantum fluctuations that make the quasi-NG modes massive, thereby suppressing their emission.

  15. Experiments with Bose-Einstein Condensation of Na and Rb

    SciTech Connect

    Bagnato, V. S.; Magalhaes, K. M. F.; Henn, E. A. L.; Ramos, E. R. F.; Seman, J. A.; Magalhaes, D. V.; Romero-Rochin, V.

    2007-09-19

    In this work we shall present the overview of our work to study trapped quantum gases in terms of global thermodynamic variables, as well as in terms of coherent modes excitation and investigation of critical phenomena within a condensate. Using cold Na atoms we have produced a sample of Bose-Einstein condensate atoms, with which we have performed the first experiments to establish an equation of state using global thermodynamic variables. In our system using Rb, we are working to continue on this direction as well as to implement and study the excitation of coherent modes on the confining potential.

  16. Noise thermometry with two weakly coupled Bose-Einstein condensates.

    PubMed

    Gati, Rudolf; Hemmerling, Börge; Fölling, Jonas; Albiez, Michael; Oberthaler, Markus K

    2006-04-07

    Here we report on the experimental investigation of thermally induced fluctuations of the relative phase between two Bose-Einstein condensates which are coupled via tunneling. The experimental control over the coupling strength and the temperature of the thermal background allows for the quantitative analysis of the phase fluctuations. Furthermore, we demonstrate the application of these measurements for thermometry in a regime where standard methods fail. With this we confirm that the heat capacity of an ideal Bose gas deviates from that of a classical gas as predicted by the third law of thermodynamics.

  17. Cooling of a Bose-Einstein Condensate by Spin Distillation

    NASA Astrophysics Data System (ADS)

    Naylor, B.; Maréchal, E.; Huckans, J.; Gorceix, O.; Pedri, P.; Vernac, L.; Laburthe-Tolra, B.

    2015-12-01

    We propose and experimentally demonstrate a new cooling mechanism leading to purification of a Bose-Einstein condensate (BEC). Our scheme starts with a BEC polarized in the lowest energy spin state. Spin excited states are thermally populated by lowering the single particle energy gap set by the magnetic field. Then, these spin-excited thermal components are filtered out, which leads to an increase of the BEC fraction. We experimentally demonstrate such cooling for a spin 3 52Cr dipolar BEC. Our scheme should be applicable to Na or Rb, with the perspective to reach temperatures below 1 nK.

  18. Hydrodynamic flow of expanding Bose-Einstein condensates

    SciTech Connect

    Brazhnyi, V. A.; Konotop, V. V.; Kamchatnov, A. M.

    2003-09-01

    We study expansion of quasi-one-dimensional (1D) Bose-Einstein condensate (BEC) after switching off the confining harmonic potential. Exact solution of dynamical equations is obtained in the framework of the hydrodynamic approximation and it is compared with the direct numerical simulation of the full problem, showing excellent agreement at realistic values of physical parameters. We analyze the maximum of the current density and estimate the velocity of expansion. The results of the 1D analysis provides also qualitative understanding of some properties of BEC expansion observed in experiments.

  19. Vortex dipole in a trapped atomic Bose-Einstein condensate

    SciTech Connect

    Zhou Qi; Zhai Hui

    2004-10-01

    We calculate the angular momentum and energy of a vortex dipole in a trapped atomic Bose-Einstein condensate. Fully analytic expressions are obtained. We apply the results to understand an interesting phenomenon in the MIT group experiment [Raman et al., Phys. Rev. Lett. 87, 210402 (2001)], an excellent agreement is achieved, and further experimental investigation is proposed to confirm this vortex dipole mechanism. We then suggest an effective generation and detection of vortex dipole for experimental realization. Application of the sum rule to calculate collective mode frequency splitting is also discussed.

  20. Cooling of a Bose-Einstein Condensate by Spin Distillation.

    PubMed

    Naylor, B; Maréchal, E; Huckans, J; Gorceix, O; Pedri, P; Vernac, L; Laburthe-Tolra, B

    2015-12-11

    We propose and experimentally demonstrate a new cooling mechanism leading to purification of a Bose-Einstein condensate (BEC). Our scheme starts with a BEC polarized in the lowest energy spin state. Spin excited states are thermally populated by lowering the single particle energy gap set by the magnetic field. Then, these spin-excited thermal components are filtered out, which leads to an increase of the BEC fraction. We experimentally demonstrate such cooling for a spin 3 ^{52}Cr dipolar BEC. Our scheme should be applicable to Na or Rb, with the perspective to reach temperatures below 1 nK.

  1. Vortex knots in a Bose-Einstein condensate.

    PubMed

    Proment, Davide; Onorato, Miguel; Barenghi, Carlo F

    2012-03-01

    We present a method for numerically building a vortex knot state in the superfluid wave function of a Bose-Einstein condensate. We integrate in time the governing Gross-Pitaevskii equation to determine evolution and shape preservation of the two (topologically) simplest vortex knots which can be wrapped over a torus. We find that the velocity of a vortex knot depends on the ratio of poloidal and toroidal radius: for smaller ratio, the knot travels faster. Finally, we show how vortex knots break up into vortex rings.

  2. Excitation spectrum of Bose-Einstein Condensates with modified dispersion

    NASA Astrophysics Data System (ADS)

    Mossman, Maren; Khamehchi, M. A.; Engels, Peter

    2015-05-01

    Bose-Einstein Condensates provide a flexible platform to model a wide variety of condensed matter phenomena. To this goal, Raman dressing schemes and dynamical lattices have emerged as a premier tool, allowing for a modification of the dispersion relation leading to spin-orbit coupling and artificial gauge fields. Using Bragg spectroscopy, we investigate the collective excitation spectrum of BECs with engineered dispersion relations and study consequences of a roton-like minimum that can be softened by changing Raman dressing parameters. We report on the current status and future directions of our experiments. This work is supported by NSF.

  3. Geometrical Pumping with a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Lu, H.-I.; Schemmer, M.; Aycock, L. M.; Genkina, D.; Sugawa, S.; Spielman, I. B.

    2016-05-01

    We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global—topological—properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local—geometrical—properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet's position in each unit cell, i.e., the polarization.

  4. Geometrical Pumping with a Bose-Einstein Condensate.

    PubMed

    Lu, H-I; Schemmer, M; Aycock, L M; Genkina, D; Sugawa, S; Spielman, I B

    2016-05-20

    We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global-topological-properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local-geometrical-properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet's position in each unit cell, i.e., the polarization.

  5. Controlling quasiparticle excitations in a trapped Bose-Einstein condensate

    SciTech Connect

    Woo, S.J.; Choi, S.; Bigelow, N.P.

    2005-08-15

    We describe an approach to quantum control of the quasiparticle excitations in a trapped Bose-Einstein condensate based on adiabatic and diabatic changes in the trap anisotropy. We describe our approach in the context of the Landau-Zener transition at the avoided crossings in the quasiparticle excitation spectrum. We find also that there can be population oscillation between different modes at the specific aspect ratios of the trapping potential at which the mode energies are almost degenerate. These effects may have implications in the expansion of an excited condensate as well as the dynamics of a moving condensate in an atomic waveguide with a varying width.

  6. Quantum dark solitons as qubits in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Shaukat, M. I.; Castro, E. V.; Terças, H.

    2017-05-01

    We study the possibility of using dark solitons in quasi-one-dimensional Bose-Einstein condensates to produce two-level systems (qubits) by exploiting the intrinsic nonlinear and coherent nature of the matter waves. We calculate the soliton spectrum and the conditions for a qubit to exist. We also compute the coupling between the phonons and the solitons and investigate the emission rate of the qubit in that case. Remarkably, the qubit lifetime is estimated to be of the order of a few seconds, being only limited by the dark-soliton "death" due to quantum evaporation.

  7. Symmetric and asymmetric solitons in linearly coupled Bose-Einstein condensates trapped in optical lattices

    SciTech Connect

    Gubeskys, Arthur; Malomed, Boris A.

    2007-06-15

    We study spontaneous symmetry breaking in a system of two parallel quasi-one-dimensional traps (cores), equipped with optical lattices (OLs) and filled with a Bose-Einstein condensate (BEC). The cores are linearly coupled by tunneling (the model may also be interpreted in terms of spatial solitons in parallel planar optical waveguides with a periodic modulation of the refractive index). Analysis of the corresponding system of linearly coupled Gross-Pitaevskii equations (GPEs) reveals that spectral band gaps of the single GPE split into subgaps. Symmetry breaking in two-component BEC solitons is studied in cases of the attractive (AA) and repulsive (RR) nonlinearity in both traps; the mixed situation, with repulsion in one trap and attraction in the other (RA), is considered too. In all the cases, stable asymmetric solitons are found, bifurcating from symmetric or antisymmetric ones (and destabilizing them), in the AA and RR systems, respectively. In either case, bistability is predicted, with a nonbifurcating stable branch, either antisymmetric or symmetric, coexisting with asymmetric ones. Solitons destabilized by the bifurcation tend to rearrange themselves into their stable asymmetric counterparts. In addition to the fundamental solitons, branches of twisted (odd) solitons in the AA system, and twisted bound states of fundamental solitons in both AA and RR systems, are found too. The impact of a phase mismatch, {delta}, between the OLs in the two cores is also studied. It is concluded that {delta}={pi}/2 only mildly deforms the picture, while {delta}={pi} changes it drastically, replacing the symmetry-breaking bifurcations by pseudobifurcations, with the branch of asymmetric solutions asymptotically approaching its symmetric or antisymmetric counterpart (in the AA and RR system, respectively), rather than splitting off from it. Also considered is a related model, for a binary BEC in a single-core trap with the OL, assuming that the two species (representing

  8. Spontaneous soliton symmetry breaking in two-dimensional coupled Bose-Einstein condensates supported by optical lattices

    SciTech Connect

    Gubeskys, Arthur; Malomed, Boris A.

    2007-10-15

    Models of two-dimensional (2D) traps, with double-well structure in the third direction, for Bose-Einstein condensates are introduced with attractive or repulsive interactions between atoms. The models are based on systems of linearly coupled 2D Gross-Pitaevskii equations, where the coupling accounts for tunneling between the wells. Each well carries an optical lattice (OL) (stable 2D solitons cannot exist without OLs). The linear coupling splits each finite band gap in the spectrum of the single-component model into two subgaps. The main subject of the work is spontaneous symmetry breaking (SSB) in two-component 2D solitons and localized vortices (SSB was not considered before in 2D settings). Using variational approximation (VA) and numerical methods, we demonstrate that, in a system with attraction or repulsion, SSB occurs in families of symmetric or antisymmetric solitons (or vortices), respectively. The corresponding bifurcation destabilizes the original solution branch and gives rise to a stable branch of asymmetric solitons or vortices. The VA provides for an accurate description of the emerging branch of asymmetric solitons. In the model with attraction, all stable branches eventually terminate due to the onset of collapse. Stable asymmetric solitons in higher finite band gaps and vortices with a multiple topological charge are found too. The models also give rise to first examples of embedded solitons and embedded vortices (the states located inside Bloch bands) in two dimensions. In the linearly coupled system with opposite signs of the nonlinearity in the two cores, two distinct types of stable solitons and vortices are found, dominated by either the self-attractive component or the self-repulsive one. In the system with a mismatch between the two OLs, a pseudobifurcation is found: when the mismatch attains its largest value ({pi}), the bifurcation does not happen, as branches of different solutions asymptotically approach each other, but fail to merge.

  9. Two-Dimensional Bright Solitons in Dipolar Bose-Einstein Condensates

    SciTech Connect

    Pedri, P.; Santos, L.

    2005-11-11

    We analyze the physics of bright solitons in 2D dipolar Bose-Einstein condensates. These solitons, which are not possible in short-range interacting gases, constitute the first realistic proposal of fully mobile stable 2D solitons in ultracold gases. In particular, we discuss the necessary conditions for the existence of stable 2D bright solitary waves by means of a 3D analysis of the lowest-lying excitations. We show that the anisotropy of the dipolar potential is crucial, since sufficiently large dipolar interactions can destabilize the 2D soliton. Additionally, we study the scattering of solitary waves, which, contrary to the contact-interacting case, is inelastic and could lead to fusion of the waves. Finally, the experimental possibilities for observability are discussed.

  10. Excitation spectra of a Bose-Einstein condensate with an angular spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Vasić, Ivana; Balaž, Antun

    2016-09-01

    A theoretical model of a Bose-Einstein condensate with angular spin-orbit coupling has recently been proposed and it has been established that a half-skyrmion represents the ground state in a certain regime of spin-orbit coupling and interaction. Here we investigate low-lying excitations of this phase by using the Bogoliubov method and numerical simulations of the time-dependent Gross-Pitaevskii equation. We find that a sudden shift of the trap bottom results in a complex two-dimensional motion of the system's center of mass that is markedly different from the response of a competing phase, and comprises two dominant frequencies. Moreover, the breathing mode frequency of the half-skyrmion is set by both the spin-orbit coupling and the interaction strength, while in the competing state it takes a universal value. Effects of interactions are especially pronounced at the transition between the two phases.

  11. Collisional Dynamics of Half-Quantum Vortices in a Spinor Bose-Einstein Condensate.

    PubMed

    Seo, Sang Won; Kwon, Woo Jin; Kang, Seji; Shin, Y

    2016-05-06

    We present an experimental study on the interaction and dynamics of half-quantum vortices (HQVs) in an antiferromagnetic spinor Bose-Einstein condensate. By exploiting the orbit motion of a vortex dipole in a trapped condensate, we perform a collision experiment of two HQV pairs, and observe that the scattering motions of the HQVs is consistent with the short-range vortex interaction that arises from nonsingular magnetized vortex cores. We also investigate the relaxation dynamics of turbulent condensates containing many HQVs, and demonstrate that spin wave excitations are generated by the collisional motions of the HQVs. The short-range vortex interaction and the HQV-magnon coupling represent two characteristics of the HQV dynamics in the spinor superfluid.

  12. Stability and structure of an anisotropically trapped dipolar Bose-Einstein condensate: Angular and linear rotons

    NASA Astrophysics Data System (ADS)

    Martin, A. D.; Blakie, P. B.

    2012-11-01

    We study theoretically Bose-Einstein condensates with polarized dipolar interactions in anisotropic traps. We map the parameter space by varying the trap frequencies and dipolar interaction strengths and find an irregular-shaped region of parameter space in which density-oscillating condensate states occur, with maximum density away from the trap center. These density-oscillating states may be biconcave (red-blood-cell-shaped), or have two or four peaks. For all trap frequencies, the condensate becomes unstable to collapse for sufficiently large dipole interaction strength. The collapse coincides with the softening of an elementary excitation. When the condensate mode is density oscillating, the character of the softening excitation is related to the structure of the condensate. We classify these excitations by linear and angular characteristics. We also find excited solutions to the Gross-Pitaevskii equation, which are always unstable.

  13. Nonlinear mode coupling and resonant excitations in two-component Bose-Einstein condensates.

    PubMed

    Xue, Ju-Kui; Li, Guan-Qiang; Zhang, Ai-Xia; Peng, Ping

    2008-01-01

    Nonlinear excitations in two-component Bose-Einstein condensates (BECs) described by two coupled Gross-Pitaevskii equations are investigated analytically and numerically. The beating phenomenon, the higher-harmonic generation, and the mixing of the excited modes are revealed by both variational approximation and numerical method. The strong excitations induced by the parametric resonance are also studied by time-periodic modulation for the intercomponent interaction. The resonance conditions in terms of the modulation frequency and the strength of intercomponent interaction are obtained analytically, which are confirmed by numerical method. Direct numerical simulations show that, when the resonance takes place, periodic phase separation and multisoliton configurations (including soliton trains, soliton pairs, and multidomain walls) can be excited. In particular, we demonstrate a method for formation of multisoliton configurations through parametric resonance in two-component BECs.

  14. Mean-field regime of trapped dipolar Bose-Einstein condensates in one and two dimensions

    SciTech Connect

    Cai Yongyong; Rosenkranz, Matthias; Lei Zhen; Bao Weizhu

    2010-10-15

    We derive rigorous one- and two-dimensional mean-field equations for cigar- and pancake-shaped dipolar Bose-Einstein condensates with arbitrary polarization angle. We show how the dipolar interaction modifies the contact interaction of the strongly confined atoms. In addition, our equations introduce a nonlocal potential, which is anisotropic for pancake-shaped condensates. We propose to observe this anisotropy via measurement of the condensate aspect ratio. We also derive analytically approximate density profiles from our equations. Both the numerical solutions of our reduced mean-field equations and the analytical density profiles agree well with numerical solutions of the full Gross-Pitaevskii equation while being more efficient to compute.

  15. Spontaneously axisymmetry-breaking phase in a binary mixture of spinor Bose-Einstein condensates

    SciTech Connect

    Xu, Z. F.; Lue, R.; You, L.; Mei, J. W.

    2010-11-15

    We study the ground-state phases for a mixture of two atomic spin-1 Bose-Einstein condensates in the presence of a weak magnetic (B) field. The ground state is found to contain a broken-axisymmetry (BA) phase due to competitions among intraspecies and interspecies spin-exchange interactions and the linear Zeeman shifts. This is in contrast to the case of a single-species spin-1 condensate, where the axisymmetry breaking results from competitions among the linear and quadratic Zeeman shifts and the intraspecies ferromagnetic interaction. All other remaining ground-state phases for the mixture are found to preserve axisymmetry. We further elaborate on the ground-state phase diagram and calculate the Bogoliubov excitation spectra of the phases. For the BA phase, there exist three Goldstone modes that attempt to restore the broken U(1) and SO(2) symmetries.

  16. Scalar field as a Bose-Einstein condensate in a Schwarzschild-de Sitter spacetime

    NASA Astrophysics Data System (ADS)

    Castellanos, Elías; Escamilla-Rivera, Celia; Lämmerzahl, Claus; Macías, Alfredo

    In this paper, we analyze some properties of a scalar field configuration, where it is considered as a trapped Bose-Einstein condensate in a Schwarzschild-de Sitter background spacetime. In a natural way, the geometry of the curved spacetime provides an effective trapping potential for the scalar field configuration. This allows us to explore some thermodynamical properties of the system. Additionally, the curved geometry of the spacetime also induces a position-dependent self-interaction parameter, which can be interpreted as a kind of gravitational Feshbach resonance, that could affect the stability of the cloud and could be used to obtain information about the interactions among the components of the system.

  17. Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices

    PubMed Central

    Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

    2015-01-01

    We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms. PMID:26597592

  18. Countersuperflow instability in miscible two-component Bose-Einstein condensates

    SciTech Connect

    Ishino, Shungo; Tsubota, Makoto; Takeuchi, Hiromitsu

    2011-06-15

    We study theoretically the instability of countersuperflow, i.e., two counterpropagating miscible superflows, in uniform two-component Bose-Einstein condensates. Countersuperflow instability causes mutual friction between the superfluids, causing a momentum exchange between the two condensates, when the relative velocity of the counterflow exceeds a critical value. The momentum exchange leads to nucleation of vortex rings from characteristic density patterns due to the nonlinear development of the instability. Expansion of the vortex rings drastically accelerates the momentum exchange, leading to a highly nonlinear regime caused by intervortex interaction and vortex reconnection between the rings. For a sufficiently large interaction between the two components, rapid expansion of the vortex rings causes isotropic turbulence and the global relative motion of the two condensates relaxes. The maximum vortex line density in the turbulence is proportional to the square of the relative velocity.

  19. Topological defect formation in rotating binary dipolar Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao-Fei; Han, Wei; Jiang, Hai-Feng; Liu, Wu-Ming; Saito, Hiroki; Zhang, Shou-Gang

    2016-12-01

    We investigate the topological defects and spin structures of a rotating binary Bose-Einstein condensate, which consists of both dipolar and scalar bosonic atoms confined in spin-dependent optical lattices, for an arbitrary orientation of the dipoles with respect to their plane of motion. Our results show that the tunable dipolar interaction, especially the orientation of the dipoles, can be used to control the direction of stripe phase and its related half-vortex sheets. In addition, it can also be used to obtain a regular arrangement of various topological spin textures, such as meron, circular and cross disgyration spin structures. We point out that such topological defects and regular arrangement of spin structures arise primarily from the long-range and anisotropic nature of dipolar interaction and its competition with the spin-dependent optical lattices and rotation.

  20. Observation of Bose-Einstein condensation in a strong synthetic magnetic field

    NASA Astrophysics Data System (ADS)

    Kennedy, Colin J.; Burton, William Cody; Chung, Woo Chang; Ketterle, Wolfgang

    2015-10-01

    Extensions of Berry’s phase and the quantum Hall effect have led to the discovery of new states of matter with topological properties. Traditionally, this has been achieved using magnetic fields or spin-orbit interactions, which couple only to charged particles. For neutral ultracold atoms, synthetic magnetic fields have been created that are strong enough to realize the Harper-Hofstadter model. We report the first observation of Bose-Einstein condensation in this system and study the Harper-Hofstadter Hamiltonian with one-half flux quantum per lattice unit cell. The diffraction pattern of the superfluid state directly shows the momentum distribution of the wavefunction, which is gauge-dependent. It reveals both the reduced symmetry of the vector potential and the twofold degeneracy of the ground state. We explore an adiabatic many-body state preparation protocol via the Mott insulating phase and observe the superfluid ground state in a three-dimensional lattice with strong interactions.

  1. Semi-classical dynamics of superradiant Rayleigh scattering in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Müller, J. H.; Witthaut, D.; le Targat, R.; Arlt, J. J.; Polzik, E. S.; Hilliard, A. J.

    2016-10-01

    Due to its coherence properties and high optical depth, a Bose-Einstein condensate [BEC] provides an ideal setting to investigate collective atom-light interactions. Superradiant light scattering [SLS] in a BEC is a fascinating example of such an interaction. It is an analogous process to Dicke superradiance, in which an electronically inverted sample decays collectively, leading to the emission of one or more light pulses in a well-defined direction. Through time-resolved measurements of the superradiant light pulses emitted by an end-pumped BEC, we study the close connection of SLS with Dicke superradiance. A 1D model of the system yields good agreement with the experimental data and shows that the dynamics result from the structures that build up in the light and matter-wave fields along the BEC. This paves the way for exploiting the atom-photon correlations generated by the superradiance.

  2. Selective distillation phenomenon in two-species Bose-Einstein condensates in open boundary optical lattices

    NASA Astrophysics Data System (ADS)

    Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo

    2015-11-01

    We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms.

  3. Fate of a Bose-Einstein condensate in the presence of spin-orbit coupling.

    PubMed

    Zhou, Qi; Cui, Xiaoling

    2013-04-05

    Intensive theoretical studies have recently predicted that a Bose-Einstein condensate will exhibit a variety of novel properties if spin-orbit coupling is present. However, an unambiguous fact has also been pointed out: Rashba coupling destroys a condensate of noninteracting bosons even in high dimensions. Therefore, a conceptually important question arises as to whether or not a condensate exists in the presence of interaction and a general type of spin-orbit coupling. Here we show that interaction qualitatively changes the ground state of bosons under Rashba spin-orbit coupling. Any infinitesimal repulsion forces bosons either to condense at one or two momentum states or to form a superfragmented state that is a superposition of infinite numbers of fragmented condensates. The superfragmented state is unstable against the anisotropy of spin-orbit coupling in systems with large numbers of particles, leading to the revival of a condensate in current experiments.

  4. Localization of a spin-orbit-coupled Bose-Einstein condensate in a bichromatic optical lattice

    NASA Astrophysics Data System (ADS)

    Cheng, Yongshan; Tang, Gaohui; Adhikari, S. K.

    2014-06-01

    We study the localization of a noninteracting and weakly interacting Bose-Einstein condensate (BEC) with spin-orbit coupling loaded in a quasiperiodic bichromatic optical lattice potential using the numerical solution and variational approximation of a binary mean-field Gross-Pitaevskii equation with two pseudospin components. We confirm the existence of the stationary localized states in the presence of the spin-orbit and Rabi couplings for an equal distribution of atoms in the two components. We find that the interaction between the spin-orbit and Rabi couplings favors the localization or delocalization of the BEC depending on the phase difference between the components. We also studied the oscillation dynamics of the localized states for an initial population imbalance between the two components.

  5. Modulational instability in binary spin-orbit-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Bhat, Ishfaq Ahmad; Mithun, T.; Malomed, B. A.; Porsezian, K.

    2015-12-01

    We study modulation instability (MI) of flat states in two-component spin-orbit-coupled (SOC) Bose-Einstein condensates (BECs) in the framework of coupled Gross-Pitaevskii equations for two components of the pseudospinor wave function. The analysis is performed for equal densities of the components. Effects of the interaction parameters, Rabi coupling, and SOC on the MI are investigated. In particular, the results demonstrate that the SOC strongly alters the commonly known MI (immiscibility) condition, g122>g1g2 , for the binary superfluid with coefficients g1 ,2 and g12 of the intra- and interspecies repulsive interactions. In fact, the binary BEC is always subject to the MI under the action of the SOC, which implies that the ground state of the system is plausibly represented by a striped phase.

  6. Vortex Reconnections and Rebounds in Trapped Atomic Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Serafini, Simone; Galantucci, Luca; Iseni, Elena; Bienaimé, Tom; Bisset, Russell N.; Barenghi, Carlo F.; Dalfovo, Franco; Lamporesi, Giacomo; Ferrari, Gabriele

    2017-04-01

    Reconnections and interactions of filamentary coherent structures play a fundamental role in the dynamics of fluids, redistributing energy and helicity among the length scales and inducing fine-scale turbulent mixing. Unlike ordinary fluids, where vorticity is a continuous field, in quantum fluids vorticity is concentrated into discrete (quantized) vortex lines turning vortex reconnections into isolated events, making it conceptually easier to study. Here, we report experimental and numerical observations of three-dimensional quantum vortex interactions in a cigar-shaped atomic Bose-Einstein condensate. In addition to standard reconnections, already numerically and experimentally observed in homogeneous systems away from boundaries, we show that double reconnections, rebounds, and ejections can also occur as a consequence of the nonhomogeneous, confined nature of the system.

  7. Bose-Einstein condensation on a manifold with non-negative Ricci curvature

    SciTech Connect

    Akant, Levent Ertuğrul, Emine Tapramaz, Ferzan Turgut, O. Teoman

    2015-01-15

    The Bose-Einstein condensation for an ideal Bose gas and for a dilute weakly interacting Bose gas in a manifold with non-negative Ricci curvature is investigated using the heat kernel and eigenvalue estimates of the Laplace operator. The main focus is on the nonrelativistic gas. However, special relativistic ideal gas is also discussed. The thermodynamic limit of the heat kernel and eigenvalue estimates is taken and the results are used to derive bounds for the depletion coefficient. In the case of a weakly interacting gas, Bogoliubov approximation is employed. The ground state is analyzed using heat kernel methods and finite size effects on the ground state energy are proposed. The justification of the c-number substitution on a manifold is given.

  8. Atom Interferometry on Sounding Rockets with Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Seidel, Stephan T.; Becker, Dennis; Lachmann, Maike D.; Herr, Waldemar; Rasel, Ernst M.; Quantus Collaboration

    2016-05-01

    One of the fundamental postulates of our description of nature is the universality of free fall, stating that the force exerted upon an object due to gravity is independent of its constitution. A precise test of this assumption is the comparison of the free fall of two ultra-cold clouds of different atomic species via atom interferometry. Since the sensitivity of the measurement is proportional to the square of the propagation time in the interferometer, it can be increased by performing the experiments in microgravity. In order to fully utilize the potential of the experiments the usage of a Bose-Einstein-Condensate as the initial state is necessary, because it is characterized by a small initial size and a low expansion velocity. As a step towards the transfer of such a system into space three sounding rocket missions with atom interferometers are currently being prepared. The launch of the first mission, aimed at the first demonstration of a Bose-Einstein-Condensate in space and an atom interferometer based on it is planned for 2016 from ESRANGE, Sweden. It will be followed by two more missions that extend the scientific goals to the creation of degenerate mixtures and dual-species atom interferometry. This research is funded by the German Space Agency DLR under Grant Number DLR 50 1131-37.

  9. Radial vortex core oscillations in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Verhelst, N.; Ichmoukhamedov, T.; Tempere, J.

    2017-07-01

    Dilute ultracold quantum gases form an ideal and highly tunable system in which superfluidity can be studied. Recently quantum turbulence in Bose-Einstein condensates was reported [PRL 103, 045310 (2009)], opening up a new experimental system that can be used to study quantum turbulence. A novel feature of this system is that vortex cores now have a finite size. This means that the vortices are no longer one dimensional features in the condensate, but that the radial behaviour and excitations might also play an important role in the study of quantum turbulence in Bose-Einstein condensates. In this paper we investigate these radial modes using a simplified variational model for the vortex core. This study results in the frequencies of the radial modes, which can be compared with the frequencies of the thoroughly studied Kelvin modes. From this comparison we find that the lowest (l = 0) radial mode has a frequency in the same order of magnitude as the Kelvin modes. However the radial modes still have a larger energy than the Kelvin modes, meaning that the Kelvin modes will still constitute the preferred channel for energy decay in quantum turbulence.

  10. Analogue gravitational phenomena in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Finazzi, Stefano

    2012-08-01

    Analogue gravity is based on the simple observation that perturbations propagating in several physical systems can be described by a quantum field theory in a curved spacetime. While phenomena like Hawking radiation are hardly detectable in astrophysical black holes, these effects may be experimentally tested in analogue systems. In this Thesis, focusing on Bose-Einstein condensates, we present our recent results about analogue models of gravity from three main perspectives: as laboratory tests of quantum field theory in curved spacetime, for the techniques that they provide to address various issues in general relativity, and as toy models of quantum gravity. The robustness of Hawking-like particle creation is investigated in flows with a single black hole horizon. Furthermore, we find that condensates with two (white and black) horizons develop a dynamical instability known in general relativity as black hole laser effect. Using techniques borrowed from analogue gravity, we also show that warp drives, which are general relativistic spacetimes allowing faster-than-light travel, are unstable. Finally, the cosmological constant issue is investigated from an analogue gravity perspective and relativistic Bose-Einstein condensates are proposed as new analogue systems with novel interesting properties.

  11. Dynamics of vortex dipoles in anisotropic Bose-Einstein condensates

    SciTech Connect

    Goodman, Roy H.; Kevrekidis, P. G.; Carretero-González, R.

    2015-04-14

    We study the motion of a vortex dipole in a Bose-Einstein condensate confined to an anisotropic trap. We focus on a system of ODEs describing the vortices' motion, which is in turn a reduced model of the Gross-Pitaevskii equation describing the condensate's motion. Using a sequence of canonical changes of variables, we reduce the dimension and simplify the equations of motion. In this study, we uncover two interesting regimes. Near a family of periodic orbits known as guiding centers, we find that the dynamics is essentially that of a pendulum coupled to a linear oscillator, leading to stochastic reversals in the overall direction of rotation of the dipole. Near the separatrix orbit in the isotropic system, we find other families of periodic, quasi-periodic, and chaotic trajectories. In a neighborhood of the guiding center orbits, we derive an explicit iterated map that simplifies the problem further. Numerical calculations are used to illustrate the phenomena discovered through the analysis. Using the results from the reduced system, we are able to construct complex periodic orbits in the original, PDE, mean-field model for Bose-Einstein condensates, which corroborates the phenomenology observed in the reduced dynamical equations.

  12. Dynamics of vortex dipoles in anisotropic Bose-Einstein condensates

    DOE PAGES

    Goodman, Roy H.; Kevrekidis, P. G.; Carretero-González, R.

    2015-04-14

    We study the motion of a vortex dipole in a Bose-Einstein condensate confined to an anisotropic trap. We focus on a system of ODEs describing the vortices' motion, which is in turn a reduced model of the Gross-Pitaevskii equation describing the condensate's motion. Using a sequence of canonical changes of variables, we reduce the dimension and simplify the equations of motion. In this study, we uncover two interesting regimes. Near a family of periodic orbits known as guiding centers, we find that the dynamics is essentially that of a pendulum coupled to a linear oscillator, leading to stochastic reversals inmore » the overall direction of rotation of the dipole. Near the separatrix orbit in the isotropic system, we find other families of periodic, quasi-periodic, and chaotic trajectories. In a neighborhood of the guiding center orbits, we derive an explicit iterated map that simplifies the problem further. Numerical calculations are used to illustrate the phenomena discovered through the analysis. Using the results from the reduced system, we are able to construct complex periodic orbits in the original, PDE, mean-field model for Bose-Einstein condensates, which corroborates the phenomenology observed in the reduced dynamical equations.« less

  13. Instability of Bose-Einstein condensation into the one-particle ground state on quantum graphs under repulsive perturbations

    SciTech Connect

    Bolte, Jens; Kerner, Joachim

    2016-04-15

    In this paper we investigate Bose-Einstein condensation into the one-particle ground state in interacting quantum many-particle systems on graphs. We extend previous results obtained for particles on an interval and show that even arbitrarily small repulsive two-particle interactions destroy the condensate in the one-particle ground state present in the non-interacting Bose gas. Our results also cover singular two-particle interactions, such as the well-known Lieb-Liniger model, in the thermodynamic limit.

  14. Fragmentation of Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Mueller, Erich J.; Ho, Tin-Lun; Ueda, Masahito; Baym, Gordon

    2006-09-01

    We present the theory of bosonic systems with multiple condensates, providing a unified description of various model systems that are found in the literature. We discuss how degeneracies, interactions, and symmetries conspire to give rise to this unusual behavior. We show that as degeneracies multiply, so do the varieties of fragmentation, eventually leading to strongly correlated states with no trace of condensation.

  15. Coreless Vortices in a Spinor Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Leslie, L. Suzanne

    Bose-Einstein condensates (BECs) provide the opportunity to study the rotational properties of quantum fluids in a low density regime. Early experiments created scalar vortices in single-component BECs, and showed that they share many of the characteristics of denser superfluids such as quantized angular momentum and persistent current. Vortices have also been created in multi-component, or spinor, BECs, in which case the wave function, or macroscopic order parameter, of the condensate is a vector. A vortex in one of the components of a spinor BEC is equivalent to a scalar vortex in a single-component condensate; the vortex core, however, can be filled with atoms in one of the other populated spin states, leaving the overall density of the cloud non-singular. ''Coreless'' vortices can be coherently created by transferring orbital angular momentum from a Laguerre-Gaussian (LG) beam to the condensate through the use of a two-photon Raman technique. This coherent population transfer interaction, along with the fundamental differences between the rotational properties of scalar and coreless vortices are discussed, and analysis is presented on several specific spin textures including two and three-component coreless vortices created in either a spin-1 or spin-2 87Rb BEC. The rotation of the vortices is confirmed directly through matter-wave interference. The coreless vortex creation process can be interpreted as the coherent transfer of optical information from the LG beam to matter: the two-photon Raman interaction in a lambda configuration writes the difference in the electric fields into the vectorial wave function of the spinor BEC. This process simultaneously transfers population between the initial and final states of the lambda system, creating a ground state coherence between the populated states. If the two Raman beams are a defocused Gaussian and a tightly focused LG beam, then the doughnut intensity profile and the azimuthal phase winding of the LG beam is

  16. Composite-boson approach to molecular Bose-Einstein condensates in mixtures of ultracold Fermi gases

    NASA Astrophysics Data System (ADS)

    Bouvrie, P. Alexander; Tichy, Malte C.; Roditi, Itzhak

    2017-02-01

    We show that an ansatz based on independent composite bosons [Phys. Rep. 463, 215 (2008), 10.1016/j.physrep.2007.11.003] accurately describes the condensate fraction of molecular Bose-Einstein condensates in ultracold Fermi gases. The entanglement between the fermionic constituents of a single Feshbach molecule then governs the many-particle statistics of the condensate, from the limit of strong interaction to close to unitarity. This result strengthens the role of entanglement as the indispensable driver of composite-boson behavior. The condensate fraction of fermion pairs at zero temperature that we compute matches excellently previous results obtained by means of fixed-node diffusion Monte Carlo methods and the Bogoliubov depletion approximation. This paves the way towards the exploration of the BEC-BCS crossover physics in mixtures of cold Fermi gases with an arbitrary number of fermion pairs as well as the implementation of Hong-Ou-Mandel-like interference experiments proposed within coboson theory.

  17. Spin-superflow turbulence in spin-1 ferromagnetic spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Fujimoto, Kazuya; Tsubota, Makoto

    2014-07-01

    Spin-superflow turbulence (SST) in spin-1 ferromagnetic spinor Bose-Einstein condensates is theoretically and numerically studied by using the spin-1 spinor Gross-Pitaevskii (GP) equations. SST is turbulence in which the disturbed spin and superfluid velocity fields are coupled. Applying the Kolmogorov-type dimensional scaling analysis to the hydrodynamic equations of spin and velocity fields, we theoretically find that the -5/3 and -7/3 power laws can appear in spectra of the superflow kinetic and the spin-dependent interaction energies, respectively. Our numerical calculation of the GP equations with a phenomenological small-scale energy dissipation confirms SST with the coexistence of disturbed spin and superfluid velocity field with two power laws.

  18. Confinement and precession of vortex pairs in coherently coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Tylutki, Marek; Pitaevskii, Lev P.; Recati, Alessio; Stringari, Sandro

    2016-04-01

    The dynamic behavior of vortex pairs in two-component coherently (Rabi) coupled Bose-Einstein condensates is investigated in the presence of harmonic trapping. We discuss the role of the surface tension associated with the domain wall connecting two vortices in condensates of atoms occupying different spin states and its effect on the precession of the vortex pair. The results, based on the numerical solution of the Gross-Pitaevskii equations, are compared with the predictions of an analytical macroscopic model and are discussed as a function of the size of the pair, the Rabi coupling, and the intercomponent interaction. We show that the increase of the Rabi coupling results in the disintegration of the domain wall into smaller pieces, connecting vortices of newly created vortex pairs. The resulting scenario is the analog of quark confinement and string breaking in quantum chromodynamics.

  19. A combined discontinuous Galerkin method for the dipolar Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Gui; Zhu, Jiang; Zhang, Rong-Pei; Cao, Shengshan

    2014-10-01

    In this work, a combined discontinuous Galerkin (DG) method, which is a hybridized mixed discontinuous Galerkin (HMDG) method combined with the direct discontinuous Galerkin (DDG) method, is proposed to compute ground states and dynamics of dipolar Bose-Einstein condensates (BECs) described by a multi-dimensional Gross-Pitaevskii equation (GPE) coupled with a first-order velocity system. Due to the adaption of the first-order velocity system instead of dipolar interactions, the proposed combined DG method avoids to evaluate integrals with high singularity. Additionally, this method keeps the conservation of the particle number. The Krylov semi-implicit method is applied to the time discretization. Finally, numerical examples are presented to demonstrate the accuracy and capability of the proposed method.

  20. Mean-field dynamics of spin-orbit coupled Bose-Einstein condensates.

    PubMed

    Zhang, Yongping; Mao, Li; Zhang, Chuanwei

    2012-01-20

    Spin-orbit coupling (SOC), the interaction between the spin and momentum of a quantum particle, is crucial for many important condensed matter phenomena. The recent experimental realization of SOC in neutral bosonic cold atoms provides a new and ideal platform for investigating spin-orbit coupled quantum many-body physics. In this Letter, we derive a generic Gross-Pitaevskii equation as the starting point for the study of many-body dynamics in spin-orbit coupled Bose-Einstein condensates. We show that different laser setups for realizing the same SOC may lead to different mean-field dynamics. Various ground state phases (stripe, phase separation, etc.) of the condensate are found in different parameter regions. A new oscillation period induced by the SOC, similar to the Zitterbewegung oscillation, is found in the center-of-mass motion of the condensate.

  1. Effective one-component description of two-component Bose-Einstein condensate dynamics

    SciTech Connect

    Dutton, Zachary; Clark, Charles W.

    2005-06-15

    We investigate dynamics in two-component Bose-Einstein condensates in the context of coupled Gross-Pitaevskii equations and derive results for the evolution of the total density fluctuations. Using these results, we show how, in many cases of interest, the dynamics can be accurately described with an effective one-component Gross-Pitaevskii equation for one of the components, with the trap and interaction coefficients determined by the relative differences in the scattering lengths. We discuss the model in various regimes, where it predicts breathing excitations, and the formation of vector solitons. An effective nonlinear evolution is predicted for some cases of current experimental interest. We then apply the model to construct quasistationary states of two-component condensates.

  2. Dark-bright solitons and their lattices in atomic Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Yan, D.; Tsitoura, F.; Kevrekidis, P. G.; Frantzeskakis, D. J.

    2015-02-01

    In the present contribution, we explore a host of different stationary states, namely dark-bright solitons and their lattices, that arise in the context of multicomponent atomic Bose-Einstein condensates. The latter are modeled by systems of coupled Gross-Pitaevskii equations with general interaction (nonlinearity) coefficients gi j. It is found that in some particular parameter ranges such solutions can be obtained in analytical form, however, numerically they are computed as existing in a far wider parametric range. Many features of the solutions under study, such as their analytical form without the trap or the stability and dynamical properties of one dark-bright soliton even in the presence of the trap are obtained analytically and corroborated numerically. Additional features, such as the stability of soliton lattice homogeneous states or their existence and stability in the presence of the trap, are examined numerically.

  3. Bose-Einstein condensation in large time-averaged optical ring potentials

    NASA Astrophysics Data System (ADS)

    Bell, Thomas A.; Glidden, Jake A. P.; Humbert, Leif; Bromley, Michael W. J.; Haine, Simon A.; Davis, Matthew J.; Neely, Tyler W.; Baker, Mark A.; Rubinsztein-Dunlop, Halina

    2016-03-01

    Interferometric measurements with matter waves are established techniques for sensitive gravimetry, rotation sensing, and measurement of surface interactions, but compact interferometers will require techniques based on trapped geometries. In a step towards the realisation of matter wave interferometers in toroidal geometries, we produce a large, smooth ring trap for Bose-Einstein condensates using rapidly scanned time-averaged dipole potentials. The trap potential is smoothed by using the atom distribution as input to an optical intensity correction algorithm. Smooth rings with a diameter up to 300 μm are demonstrated. We experimentally observe and simulate the dispersion of condensed atoms in the resulting potential, with good agreement serving as an indication of trap smoothness. Under time of flight expansion we observe low energy excitations in the ring, which serves to constrain the lower frequency limit of the scanned potential technique. The resulting ring potential will have applications as a waveguide for atom interferometry and studies of superfluidity.

  4. Vortex structures of rotating spin-orbit-coupled Bose-Einstein condensates

    SciTech Connect

    Zhou Xiangfa; Zhou Jing; Wu Congjun

    2011-12-15

    We consider the quasi-two-dimensional two-component Bose-Einstein condensates with Rashba spin-orbit (SO) coupling in a rotating trap. The rotation angular velocity couples to the mechanical angular momentum, which contains a noncanonical part arising from SO coupling. The effects of an external Zeeman term favoring spin polarization along the radial direction is also considered, which has the same form as the noncanonical part of the mechanical angular momentum. The rotating condensate exhibits a variety of rich structures by varying the strengths of the trapping potential and interaction. With a strong trapping potential, the condensate exhibits a half-quantum vortex-lattice configuration. Such a configuration is driven to the normal one by introducing the external radial Zeeman field. In the case of a weak trap potential, the condensate exhibits a multidomain pattern of plane-wave states under the external radial Zeeman field.

  5. Planck-scale-induced speed of sound in a trapped Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Rivas, J. I.; Dominguez-Rocha, V.

    2014-06-01

    In the present work, we analyze the corrections caused by an anomalous dispersion relation, suggested in several quantum gravity models, upon the speed of sound in a weakly interacting Bose-Einstein condensate, trapped in a potential of the form V(r)\\sim r^{2} . We show that the corresponding ground-state energy and consequently, the associated speed of sound, present corrections with respect to the usual case, which may be used to explore the sensitivity to Planck-scale effects on these relevant properties associated with the condensate. Indeed, we stress that this type of macroscopic bodies may be more sensitive, under certain conditions, to Planck-scale manifestations than its constituents. In addition, we prove that the inclusion of a trapping potential, together with many-body contributions, improves the sensitivity to Planck-scale signals, compared to the homogeneous system.

  6. Bose-Einstein condensates on tilted lattices: Coherent, chaotic, and subdiffusive dynamics

    SciTech Connect

    Kolovsky, Andrey R.; Gomez, Edgar A.; Korsch, Hans Juergen

    2010-02-15

    The dynamics of a (quasi-) one-dimensional interacting atomic Bose-Einstein condensate in a tilted optical lattice is studied in a discrete mean-field approximation, i.e., in terms of the discrete nonlinear Schroedinger equation. If the static field is varied, the system shows a plethora of dynamical phenomena. In the strong field limit, we demonstrate the existence of (almost) nonspreading states which remain localized on the lattice region populated initially and show coherent Bloch oscillations with fractional revivals in the momentum space (so-called quantum carpets). With decreasing field, the dynamics becomes irregular, however, still confined in configuration space. For even weaker fields, we find subdiffusive dynamics with a wave-packet width growing as t{sup 1/4}.

  7. Non-Hermitian matter-wave mixing in Bose-Einstein condensates: Dissipation-induced amplification

    NASA Astrophysics Data System (ADS)

    Wüster, S.; El-Ganainy, R.

    2017-07-01

    We investigate the nonlinear scattering dynamics in interacting atomic Bose-Einstein condensates under non-Hermitian dissipative conditions. We show that, by carefully engineering a momentum-dependent atomic loss profile, one can achieve matter-wave amplification through four-wave mixing in a quasi-one-dimensional nearly-free-space setup—a process that is forbidden in the counterpart Hermitian systems due to energy mismatch. Additionally, we show that similar effects lead to rich nonlinear dynamics in higher dimensions. Finally, we propose a physical realization for selectively tailoring the momentum-dependent atomic dissipation. Our strategy is based on a two-step process: (i) exciting atoms to narrow Rydberg or metastable excited states, and (ii) introducing loss through recoil; all while leaving the bulk condensate intact due to protection by quantum interference.

  8. Half-Quantum Vortices in an Antiferromagnetic Spinor Bose-Einstein Condensate.

    PubMed

    Seo, Sang Won; Kang, Seji; Kwon, Woo Jin; Shin, Yong-il

    2015-07-03

    We report on the observation of half-quantum vortices (HQVs) in the easy-plane polar phase of an antiferromagnetic spinor Bose-Einstein condensate. Using in situ magnetization-sensitive imaging, we observe that pairs of HQVs with opposite core magnetization are generated when singly charged quantum vortices are injected into the condensate. The dynamics of HQV pair formation is characterized by measuring the temporal evolutions of the pair separation distance and the core magnetization, which reveals the short-range nature of the repulsive interactions between the HQVs. We find that spin fluctuations arising from thermal population of transverse magnon excitations do not significantly affect the HQV pair formation dynamics. Our results demonstrate the instability of a singly charged vortex in the antiferromagnetic spinor condensate.

  9. Collisions of Solitons and Vortex Rings in Cylindrical Bose-Einstein Condensates

    SciTech Connect

    Komineas, Stavros; Brand, Joachim

    2005-09-09

    Interactions of solitary waves in a cylindrically confined Bose-Einstein condensate are investigated by simulating their head-on collisions. Slow vortex rings and fast solitons are found to collide elastically contrary to the situation in the three-dimensional homogeneous Bose gas. Strongly inelastic collisions are absent for low density condensates but occur at higher densities for intermediate velocities. The scattering behavior is rationalized by use of dispersion diagrams. During inelastic collisions, spherical shell-like structures of low density are formed and they eventually decay into depletion droplets with solitary-wave features. The relation to similar shells observed in a recent experiment by Ginsberg et al. [Phys. Rev. Lett. 94, 040403 (2005)] is discussed.

  10. Dissipative dynamics of the Josephson effect in binary Bose-Einstein-condensed mixtures

    NASA Astrophysics Data System (ADS)

    Burmistrov, S. N.

    2011-06-01

    The dissipative dynamics of a pointlike Josephson junction in binary Bose-Einstein-condensed mixtures is analyzed within the framework of the model of a tunneling Hamiltonian. The transmission of unlike particles across a junction is described by the different transmission amplitudes. The effective action that describes the dynamics of the phase differences across the junction for each of two condensed components is derived by employing the functional integration method. In the low-frequency limit the dynamics of a Josephson junction can be described by two coupled equations in terms of the potential energy and dissipative Rayleigh function using a mechanical analogy. The interplay between mass currents of each mixture component appears in the second-order term in the tunneling amplitudes due to the interspecies hybridizing interaction. The asymmetric case of the binary mixtures with different concentrations and order parameters is considered as well.

  11. Bose-Einstein condensates with localized spin-orbit coupling: Soliton complexes and spinor dynamics

    NASA Astrophysics Data System (ADS)

    Kartashov, Yaroslav V.; Konotop, Vladimir V.; Zezyulin, Dmitry A.

    2014-12-01

    Spin-orbit (SO) coupling can be introduced in a Bose-Einstein condensate (BEC) as a gauge potential acting only in a localized spatial domain. The effect of such a SO "defect" can be understood by transforming the system to the integrable vector model. The properties of the SO BEC change drastically if the SO defect is accompanied by the Zeeman splitting. In such a nonintegrable system, the SO defect qualitatively changes the character of soliton interactions and allows for formation of stable nearly scalar soliton complexes with almost all atoms concentrated in only one dark state. These solitons exist only if the number of particles exceeds a threshold value. We also report on the possibility of transmission and reflection of a soliton upon its scattering on the SO defect. Scattering strongly affects the pseudospin polarization and can induce pseudospin precession. The scattering can also result in almost complete atomic transfer between the dark states.

  12. Casimir Forces and Quantum Friction from Ginzburg Radiation in Atomic Bose-Einstein Condensates.

    PubMed

    Marino, Jamir; Recati, Alessio; Carusotto, Iacopo

    2017-01-27

    We theoretically propose an experimentally viable scheme to use an impurity atom in an atomic Bose-Einstein condensate, in order to realize condensed-matter analogs of quantum vacuum effects. In a suitable atomic level configuration, the collisional interaction between the impurity atom and the density fluctuations in the condensate can be tailored to closely reproduce the electric-dipole coupling of quantum electrodynamics. By virtue of this analogy, we recover and extend the paradigm of electromagnetic vacuum forces to the domain of cold atoms, showing in particular the emergence, at supersonic atomic speeds, of a novel power-law scaling of the Casimir force felt by the atomic impurity, as well as the occurrence of a quantum frictional force, accompanied by the Ginzburg emission of Bogoliubov quanta. Observable consequences of these quantum vacuum effects in realistic spectroscopic experiments are discussed.

  13. Domain wall model in the galactic Bose-Einstein condensate halo

    SciTech Connect

    Souza, J.C.C. de; Pires, M.O.C. E-mail: marcelo.pires@ufabc.edu.br

    2013-05-01

    We assume that the galactic dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate [1], can present topological defects, namely domain walls, arising as the dark soliton solution for the Gross-Pitaevskii equation in a self-graviting potential. We investigate the influence that such substructures would have in the gravitational interactions within a galaxy. We find that, for the simple domain wall model proposed, the effects are too small to be identified, either by means of a local measurement of the gradient of the gravitational field or by analysing galaxy rotation curves. In the first case, the gradient of the gravitational field in the vicinity of the domain wall would be 10{sup −31} (m/s{sup 2})/m. In the second case, the ratio of the tangential velocity correction of a star due to the presence of the domain wall to the velocity in the spherical symmetric case would be 10{sup −8}.

  14. Three-Body Losses in Trapped Bose-Einstein Condensed Gases

    NASA Astrophysics Data System (ADS)

    Kim, Yeong E.; Zubarev, Alexander L.

    2004-05-01

    A time-dependent Kohn-Sham (KS)-like equation for N bosons in a trap [1] is generalized for the case of inelastic collisions [2]. We derive adiabatic equations which are used to calculate the nonlinear dynamics of the Bose-Einstein condensate (BEC) and non-mean field corrections due to the three-body recombination. We find that the calculated corrections are about 13 times larger for 3D trapped dilute bose gases and about 7 times larger for 1D trapped weakly interacting bose gases when compared with the corresponding corrections for the ground state energy and for the collective frequencies. The comparising of the our numerical calculations with corresponding experimental data will be discussed. [1] Y.E. Kim and A.L. Zubarev, Phys. Rev. A67, 015602 (2003). [2] Y.E. Kim and A.L. Zubarev, Phys. Rev. A (in print); cond-mat/0305089.

  15. Dark matter as a Bose-Einstein Condensate: the relativistic non-minimally coupled case

    SciTech Connect

    Bettoni, Dario; Colombo, Mattia; Liberati, Stefano E-mail: mattia.colombo@studenti.unitn.it

    2014-02-01

    Bose-Einstein Condensates have been recently proposed as dark matter candidates. In order to characterize the phenomenology associated to such models, we extend previous investigations by studying the general case of a relativistic BEC on a curved background including a non-minimal coupling to curvature. In particular, we discuss the possibility of a two phase cosmological evolution: a cold dark matter-like phase at the large scales/early times and a condensed phase inside dark matter halos. During the first phase dark matter is described by a minimally coupled weakly self-interacting scalar field, while in the second one dark matter condensates and, we shall argue, develops as a consequence the non-minimal coupling. Finally, we discuss how such non-minimal coupling could provide a new mechanism to address cold dark matter paradigm issues at galactic scales.

  16. Superfluidity of Bose-Einstein condensates in toroidal traps with nonlinear lattices

    SciTech Connect

    Yulin, A. V.; Konotop, V. V.; Bludov, Yu. V.; Kuzmiak, V.; Salerno, M.

    2011-12-15

    Superfluid properties of Bose-Einstein condensates (BEC) in toroidal quasi-one-dimensional traps are investigated in the presence of periodic scattering length modulations along the ring. The existence of several types of stable periodic waves, ranging from almost uniform to very fragmented chains of weakly interacting and equally spaced solitons, is demonstrated. We show that these waves may support persistent atomic currents and sound waves with spectra of Bogoliubov type. Fragmented condensates can be viewed as arrays of Josephson junctions and the current as a BEC manifestation of the dc-Josephson effect. The influence of linear defects on BEC superfluidity has been also investigated. We found that for subcritical velocities, linear defects that are static with respect to the lattice (while the condensate moves in respect to both the optical lattice and the defect) preserve the BEC superfluidity.

  17. Bose-Einstein quantum phase transition in an optical lattice model

    SciTech Connect

    Aizenman, Michael; Lieb, Elliott H.; Seiringer, Robert; Solovej, Jan Philip; Yngvason, Jakob

    2004-08-01

    Bose-Einstein condensation (BEC) in cold gases can be turned on and off by an external potential, such as that presented by an optical lattice. We present a model of this phenomenon which we are able to analyze rigorously. The system is a hard core lattice gas at half of the maximum density and the optical lattice is modeled by a periodic potential of strength {lambda}. For small {lambda} and temperature, BEC is proved to occur, while at large {lambda} or temperature there is no BEC. At large {lambda} the low-temperature states are in a Mott insulator phase with a characteristic gap that is absent in the BEC phase. The interparticle interaction is essential for this transition, which occurs even in the ground state. Surprisingly, the condensation is always into the p=0 mode in this model, although the density itself has the periodicity of the imposed potential.

  18. Three-dimensional vortex structures in a rotating dipolar Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Kishor Kumar, Ramavarmaraja; Sriraman, Thangarasu; Fabrelli, Henrique; Muruganandam, Paulsamy; Gammal, Arnaldo

    2016-08-01

    We study three-dimensional vortex lattice structures in purely dipolar Bose-Einstein condensate (BEC). By using the mean-field approximation, we obtain a stability diagram for the vortex states in purely dipolar BECs as a function of harmonic trap aspect ratio (λ) and dipole-dipole interaction strength (D) under rotation. Rotating the condensate within the unstable region leads to collapse while in the stable region furnishes stable vortex lattices of dipolar BECs. We analyse stable vortex lattice structures by solving the three-dimensional time-dependent Gross-Pitaevskii equation in imaginary time. Further, the stability of vortex states is examined by evolution in real-time. We also investigate the distribution of vortices in a fully anisotropic trap by increasing eccentricity of the external trapping potential. We observe the breaking up of the condensate in two parts with an equal number of vortices on each when the trap is sufficiently weak, and the rotation frequency is high.

  19. Robust vortex lines, vortex rings, and hopfions in three-dimensional Bose-Einstein condensates

    DOE PAGES

    Bisset, R. N.; Wang, Wenlong; Ticknor, Christopher; ...

    2015-12-07

    Performing a systematic Bogoliubov–de Gennes spectral analysis, we illustrate that stationary vortex lines, vortex rings, and more exotic states, such as hopfions, are robust in three-dimensional atomic Bose-Einstein condensates, for large parameter intervals. Importantly, we find that the hopfion can be stabilized in a simple parabolic trap, without the need for trap rotation or inhomogeneous interactions. We supplement our spectral analysis by studying the dynamics of such stationary states; we find them to be robust against significant perturbations of the initial state. In the unstable regimes, we not only identify the unstable mode, such as a quadrupolar or hexapolar mode,more » but we also observe the corresponding instability dynamics. Moreover, deep in the Thomas-Fermi regime, we investigate the particlelike behavior of vortex rings and hopfions.« less

  20. Deterministic creation, pinning, and manipulation of quantized vortices in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Samson, E. C.; Wilson, K. E.; Newman, Z. L.; Anderson, B. P.

    2016-02-01

    We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles for the superfluid atomic gas; by controlling the positions of the beams within the plane of the BEC, superfluid flow is deterministically established around each beam such that two vortices of opposite circulation are generated by the motion of the beams, with each vortex pinned to the in situ position of a laser beam. We study the vortex creation process, and show that the vortices can be moved about within the BEC by translating the positions of the laser beams. This technique can serve as a building block in future experimental techniques to create, on-demand, deterministic arrangements of few or many vortices within a BEC for precise studies of vortex dynamics and vortex interactions.

  1. Fock-state dynamics in Raman photoassociation of Bose-Einstein condensates

    SciTech Connect

    Olsen, M.K.; Bradley, A.S.; Cavalcanti, S.B.

    2004-09-01

    By stochastic modeling of the process of Raman photoassociation of Bose-Einstein condensates, we show that, the farther the initial quantum state is from a coherent state, the farther the one-dimensional predictions are from those of the commonly used zero-dimensional approach. We compare the dynamics of condensates, initially in different quantum states, finding that, even when the quantum prediction for an initial coherent state is relatively close to the Gross-Pitaevskii prediction, an initial Fock state gives qualitatively different predictions. We also show that this difference is not present in a single-mode type of model, but that the quantum statistics assume a more important role as the dimensionality of the model is increased. This contrasting behavior in different dimensions, well known with critical phenomena in statistical mechanics, makes itself plainly visible here in a mesoscopic system and is a strong demonstration of the need to consider physically realistic models of interacting condensates.

  2. Loading of a Bose-Einstein condensate into an optical lattice: The excitation of collective modes

    NASA Astrophysics Data System (ADS)

    Plata, J.

    2004-03-01

    The dynamics of a Bose-Einstein condensate in a harmonic trap with a nonadiabatically loaded optical lattice is studied analytically. As the global effect of the optical potential can be described in terms of a renormalized interaction coupling constant and of an effective mass in the laser direction, a fast loading can be understood as a sudden change of those characteristic parameters. In this approach, a standard scaling transformation is applied to study the resulting dynamics, in particular, the generation of collective modes. The relevance of the excited modes to the interference patterns obtained after free expansion is analyzed. The applicability of trap-frequency adjustments as a strategy for suppressing the loading induced excitations is discussed.

  3. Adiabatically tuning quantized supercurrents in an annular Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Hou, Junpeng; Luo, Xi-Wang; Sun, Kuei; Zhang, Chuanwei

    2017-07-01

    The ability to generate and tune quantized persistent supercurrents is crucial for building superconducting or atomtronic devices with novel functionalities. In ultracold atoms, previous methods for generating quantized supercurrents are generally based on dynamical processes to prepare atoms in metastable excited states. Here, we show that arbitrary quantized circulation states can be adiabatically prepared and tuned as the ground state of a ring-shaped Bose-Einstein condensate by utilizing spin-orbital-angular-momentum (SOAM) coupling and an external potential. There exists superfluid hysteresis for tuning supercurrents between different quantization values with nonlinear atomic interactions, which is explained by developing a nonlinear Landau-Zener theory. Our work will provide a powerful platform for studying SOAM-coupled ultracold atomic gases and building atomtronic circuits.

  4. Extracting Lyapunov exponents from the echo dynamics of Bose-Einstein condensates on a lattice

    NASA Astrophysics Data System (ADS)

    Tarkhov, Andrei E.; Wimberger, Sandro; Fine, Boris V.

    2017-08-01

    We propose theoretically an experimentally realizable method to demonstrate the Lyapunov instability and to extract the value of the largest Lyapunov exponent for a chaotic many-particle interacting system. The proposal focuses specifically on a lattice of coupled Bose-Einstein condensates in the classical regime describable by the discrete Gross-Pitaevskii equation. We suggest to use imperfect time reversal of the system's dynamics known as the Loschmidt echo, which can be realized experimentally by reversing the sign of the Hamiltonian of the system. The routine involves tracking and then subtracting the noise of virtually any observable quantity before and after the time reversal. We support the theoretical analysis by direct numerical simulations demonstrating that the largest Lyapunov exponent can indeed be extracted from the Loschmidt echo routine. We also discuss possible values of experimental parameters required for implementing this proposal.

  5. Evolution of an isolated monopole in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Tiurev, Konstantin; Kuopanportti, Pekko; Gunyhó, András Márton; Ueda, Masahito; Möttönen, Mikko

    2016-11-01

    We simulate the decay dynamics of an isolated monopole defect in the nematic vector of a spin-1 Bose-Einstein condensate during the polar-to-ferromagnetic phase transition of the system. Importantly, the decay of the monopole occurs in the absence of external magnetic fields and is driven principally by the dynamical instability due to the ferromagnetic spin-exchange interactions. An initial isolated monopole is observed to relax into a polar-core spin vortex, thus demonstrating the spontaneous transformation of a point defect of the polar order parameter manifold to a line defect of the ferromagnetic manifold. We also investigate the dynamics of an isolated monopole pierced by a quantum vortex line with winding number κ . It is shown to decay into a coreless Anderson-Toulouse vortex if κ =1 and into a singular vortex with an empty core if κ =2 . In both cases, the resulting vortex is also encircled by a polar-core vortex ring.

  6. Impurities as a quantum thermometer for a Bose-Einstein Condensate.

    PubMed

    Sabín, Carlos; White, Angela; Hackermuller, Lucia; Fuentes, Ivette

    2014-09-22

    We introduce a primary thermometer which measures the temperature of a Bose-Einstein Condensate in the sub-nK regime. We show, using quantum Fisher information, that the precision of our technique improves the state-of-the-art in thermometry in the sub-nK regime. The temperature of the condensate is mapped onto the quantum phase of an atomic dot that interacts with the system for short times. We show that the highest precision is achieved when the phase is dynamical rather than geometric and when it is detected through Ramsey interferometry. Standard techniques to determine the temperature of a condensate involve an indirect estimation through mean particle velocities made after releasing the condensate. In contrast to these destructive measurements, our method involves a negligible disturbance of the system.

  7. Multistability in an optomechanical system with a two-component Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Dong, Ying; Ye, Jinwu; Pu, Han

    2011-03-01

    We investigate a system consisting of a two-component Bose-Einstein condensate interacting dispersively with a Fabry-Perot optical cavity where the two components of the condensate are resonantly coupled to each other by another classical field. The key feature of this system is that the atomic motional degrees of freedom and the internal pseudospin degrees of freedom are coupled to the cavity field simultaneously, hence an effective spin-orbital coupling within the condensate is induced by the cavity. The interplay among the atomic center-of-mass motion, the atomic collective spin, and the cavity field leads to a strong nonlinearity, resulting in multistable behavior in both matter wave and light wave at the few-photon level.

  8. Mean-Field Dynamics of Spin-Orbit Coupled Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Zhang, Yongping; Mao, Li; Zhang, Chuanwei

    2012-01-01

    Spin-orbit coupling (SOC), the interaction between the spin and momentum of a quantum particle, is crucial for many important condensed matter phenomena. The recent experimental realization of SOC in neutral bosonic cold atoms provides a new and ideal platform for investigating spin-orbit coupled quantum many-body physics. In this Letter, we derive a generic Gross-Pitaevskii equation as the starting point for the study of many-body dynamics in spin-orbit coupled Bose-Einstein condensates. We show that different laser setups for realizing the same SOC may lead to different mean-field dynamics. Various ground state phases (stripe, phase separation, etc.) of the condensate are found in different parameter regions. A new oscillation period induced by the SOC, similar to the Zitterbewegung oscillation, is found in the center-of-mass motion of the condensate.

  9. 3/2-Body Correlations and Coherence in Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Kita, Takafumi

    2017-04-01

    We construct a variational wave function for the ground state of weakly interacting bosons that gives a lower energy than the mean-field Girardeau-Arnowitt (or Hartree-Fock-Bogoliubov) theory. This improvement is brought about by incorporating the dynamical 3/2-body processes where one of two colliding non-condensed particles drops into the condensate and vice versa. The processes are also shown to transform the one-particle excitation spectrum into a bubbling mode with a finite lifetime even in the long-wavelength limit. These 3/2-body processes, which give rise to dynamical exchange of particles between the non-condensate reservoir and condensate absent in ideal gases, are identified as a key mechanism for realizing and sustaining macroscopic coherence in Bose-Einstein condensates.

  10. Collective excitation of Bose-Einstein condensates in the transition region between three and one dimensions

    SciTech Connect

    Kottke, M.; Schulte, T.; Hellweg, D.; Drenkelforth, S.; Ertmer, W.; Arlt, J. J.; Cacciapuoti, L.

    2005-11-15

    We measure the frequency of the low m=0 quadrupolar excitation mode of weakly interacting Bose-Einstein condensates in the transition region from the three-dimensional (3D) to the 1D mean-field regime. Various effects shifting the frequency of the mode are discussed. In particular we take the dynamic coupling of the condensate with the thermal component at finite temperature into account using a time-dependent Hartree-Fock-Bogoliubov treatment developed by Giorgini [Phys. Rev. A, 61, 063615 (2000)]. We show that the frequency rises in the transition from 3D to 1D, in good agreement with the theoretical prediction of Menotti and Stringari [Phys. Rev. A 66, 043610 (2002)].

  11. Interferometry with non-classical motional states of a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    van Frank, S.; Negretti, A.; Berrada, T.; Bücker, R.; Montangero, S.; Schaff, J.-F.; Schumm, T.; Calarco, T.; Schmiedmayer, J.

    2014-05-01

    The Ramsey interferometer is a prime example of precise control at the quantum level. It is usually implemented using internal states of atoms, molecules or ions, for which powerful manipulation procedures are now available. Whether it is possible to control external degrees of freedom of more complex, interacting many-body systems at this level remained an open question. Here we demonstrate a two-pulse Ramsey-type interferometer for non-classical motional states of a Bose-Einstein condensate in an anharmonic trap. The control sequences used to manipulate the condensate wavefunction are obtained from optimal control theory and are directly optimized to maximize the interferometric contrast. They permit a fast manipulation of the atomic ensemble compared to the intrinsic decay processes and many-body dephasing effects. This allows us to reach an interferometric contrast of 92% in the experimental implementation.

  12. Impurities as a quantum thermometer for a Bose-Einstein condensate

    PubMed Central

    Sabín, Carlos; White, Angela; Hackermuller, Lucia; Fuentes, Ivette

    2014-01-01

    We introduce a primary thermometer which measures the temperature of a Bose-Einstein Condensate in the sub-nK regime. We show, using quantum Fisher information, that the precision of our technique improves the state-of-the-art in thermometry in the sub-nK regime. The temperature of the condensate is mapped onto the quantum phase of an atomic dot that interacts with the system for short times. We show that the highest precision is achieved when the phase is dynamical rather than geometric and when it is detected through Ramsey interferometry. Standard techniques to determine the temperature of a condensate involve an indirect estimation through mean particle velocities made after releasing the condensate. In contrast to these destructive measurements, our method involves a negligible disturbance of the system. PMID:25241663

  13. Experimental apparatus to study cold collisions in sodium spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Nematollahi, Delaram; Foster, Aaron; Yates, Kyle; Altermatt, Joseph; Lee, Hyoyeon; Zhang, Qimin; Schwettmann, Arne

    2015-05-01

    We present our progress on building an apparatus to study matter-wave quantum optics in spin space, including our design of the sodium oven, Zeeman slower, vacuum and laser systems. The nonlinear interaction needed to implement quantum optical devices with matter waves will be provided by spin-exchange collisions in a sodium spinor Bose-Einstein condensate. Microwave dressing will allow us to exert precise control over the collisional dynamics and tune the system to behave as an interferometer in spin space with reduced noise, or as a phase-sensitive amplifier for sensitive atom number measurements. Apart from microwave dressing, we are also planning to study the effect of Rydberg excitations on the collisional spin dynamics of the gas.

  14. Robust vortex lines, vortex rings, and hopfions in three-dimensional Bose-Einstein condensates

    SciTech Connect

    Bisset, R. N.; Wang, Wenlong; Ticknor, Christopher; Carretero-Gonzalez, R.; Frantzeskakis, D. J.; Collins, Lee A.; Kevrekidis, P. G.

    2015-12-07

    Performing a systematic Bogoliubov–de Gennes spectral analysis, we illustrate that stationary vortex lines, vortex rings, and more exotic states, such as hopfions, are robust in three-dimensional atomic Bose-Einstein condensates, for large parameter intervals. Importantly, we find that the hopfion can be stabilized in a simple parabolic trap, without the need for trap rotation or inhomogeneous interactions. We supplement our spectral analysis by studying the dynamics of such stationary states; we find them to be robust against significant perturbations of the initial state. In the unstable regimes, we not only identify the unstable mode, such as a quadrupolar or hexapolar mode, but we also observe the corresponding instability dynamics. Moreover, deep in the Thomas-Fermi regime, we investigate the particlelike behavior of vortex rings and hopfions.

  15. Interferometry with non-classical motional states of a Bose-Einstein condensate.

    PubMed

    van Frank, S; Negretti, A; Berrada, T; Bücker, R; Montangero, S; Schaff, J-F; Schumm, T; Calarco, T; Schmiedmayer, J

    2014-05-30

    The Ramsey interferometer is a prime example of precise control at the quantum level. It is usually implemented using internal states of atoms, molecules or ions, for which powerful manipulation procedures are now available. Whether it is possible to control external degrees of freedom of more complex, interacting many-body systems at this level remained an open question. Here we demonstrate a two-pulse Ramsey-type interferometer for non-classical motional states of a Bose-Einstein condensate in an anharmonic trap. The control sequences used to manipulate the condensate wavefunction are obtained from optimal control theory and are directly optimized to maximize the interferometric contrast. They permit a fast manipulation of the atomic ensemble compared to the intrinsic decay processes and many-body dephasing effects. This allows us to reach an interferometric contrast of 92% in the experimental implementation.

  16. Casimir Forces and Quantum Friction from Ginzburg Radiation in Atomic Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Marino, Jamir; Recati, Alessio; Carusotto, Iacopo

    2017-01-01

    We theoretically propose an experimentally viable scheme to use an impurity atom in an atomic Bose-Einstein condensate, in order to realize condensed-matter analogs of quantum vacuum effects. In a suitable atomic level configuration, the collisional interaction between the impurity atom and the density fluctuations in the condensate can be tailored to closely reproduce the electric-dipole coupling of quantum electrodynamics. By virtue of this analogy, we recover and extend the paradigm of electromagnetic vacuum forces to the domain of cold atoms, showing in particular the emergence, at supersonic atomic speeds, of a novel power-law scaling of the Casimir force felt by the atomic impurity, as well as the occurrence of a quantum frictional force, accompanied by the Ginzburg emission of Bogoliubov quanta. Observable consequences of these quantum vacuum effects in realistic spectroscopic experiments are discussed.

  17. Dynamics of straight vortex filaments in a Bose-Einstein condensate with the Gaussian density profile

    NASA Astrophysics Data System (ADS)

    Ruban, V. P.

    2017-06-01

    The dynamics of interacting quantized vortex filaments in a rotating Bose-Einstein condensate existing in the Thomas-Fermi regime at zero temperature and obeying the Gross-Pitaevskii equation has been considered in the hydrodynamic "nonelastic" approximation. A noncanonical Hamilton equation of motion for the macroscopically averaged vorticity has been derived for a smoothly inhomogeneous array of filaments (vortex lattice) taking into account spatial nonuniformity of the equilibrium density of the condensate, which is determined by the trap potential. The minimum of the corresponding Hamiltonian describes the static configuration of the deformed vortex lattice against the preset density background. The condition of minimum can be reduced to a nonlinear second-order partial differential vector equation for which some exact and approximate solutions are obtained. It has been shown that if the condensate density has an anisotropic Gaussian profile, the equation of motion for the averaged vorticity has solutions in the form of a vector exhibiting a nontrivial time dependence, but homogeneous in space. An integral representation has also been obtained for the matrix Green function that determines the nonlocal Hamiltonian of a system of several quantized vortices of an arbitrary shape in a Bose-Einstein condensate with the Gaussian density. In particular, if all filaments are straight and oriented along one of the principal axes of the ellipsoid, we have a finitedimensional reduction that can describe the dynamics of the system of pointlike vortices against an inhomogeneous background. A simple approximate expression is proposed for the 2D Green function with an arbitrary density profile and is compared numerically with the exact result in the Gaussian case. The corresponding approximate equations of motion, describing the long-wavelength dynamics of interacting vortex filaments in condensates with a density depending only on transverse coordinates, have been derived.

  18. Bose Einstein correlations in W-pair decays with an event-mixing technique

    NASA Astrophysics Data System (ADS)

    ALEPH Collaboration; Schael, S.; Barate, R.; Brunelière, R.; de Bonis, I.; Decamp, D.; Goy, C.; Jézéquel, S.; Lees, J.-P.; Martin, F.; Merle, E.; Minard, M.-N.; Pietrzyk, B.; Trocmé, B.; Bravo, S.; Casado, M. P.; Chmeissani, M.; Crespo, J. M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Martinez, M.; Pacheco, A.; Ruiz, H.; Colaleo, A.; Creanza, D.; de Filippis, N.; de Palma, M.; Iaselli, G.; Maggi, G.; Maggi, M.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Barklow, T.; Buchmüller, O.; Cattaneo, M.; Clerbaux, B.; Drevermann, H.; Forty, R. W.; Frank, M.; Gianotti, F.; Hansen, J. B.; Harvey, J.; Hutchcroft, D. E.; Janot, P.; Jost, B.; Kado, M.; Mato, P.; Moutoussi, A.; Ranjard, F.; Rolandi, L.; Schlatter, D.; Sguazzoni, G.; Teubert, F.; Valassi, A.; Videau, I.; Badaud, F.; Dessagne, S.; Falvard, A.; Fayolle, D.; Gay, P.; Jousset, J.; Michel, B.; Monteil, S.; Pallin, D.; Pascolo, J. M.; Perret, P.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Kraan, A. C.; Nilsson, B. S.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Blondel, A.; Brient, J.-C.; Machefert, F.; Rougé, A.; Videau, H.; Ciulli, V.; Focardi, E.; Parrini, G.; Antonelli, A.; Antonelli, M.; Bencivenni, G.; Bossi, F.; Capon, G.; Cerutti, F.; Chiarella, V.; Laurelli, P.; Mannocchi, G.; Murtas, G. P.; Passalacqua, L.; Kennedy, J.; Lynch, J. G.; Negus, P.; O'Shea, V.; Thompson, A. S.; Wasserbaech, S.; Cavanaugh, R.; Dhamotharan, S.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Putzer, A.; Stenzel, H.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Cameron, W.; Davies, G.; Dornan, P. J.; Girone, M.; Marinelli, N.; Nowell, J.; Rutherford, S. A.; Sedgbeer, J. K.; Thompson, J. C.; White, R.; Ghete, V. M.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bouhova-Thacker, E.; Bowdery, C. K.; Clarke, D. P.; Ellis, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Pearson, M. R.; Robertson, N. A.; Smizanska, M.; van der Aa, O.; Delaere, C.; Leibenguth, G.; Lemaitre, V.; Blumenschein, U.; Hölldorfer, F.; Jakobs, K.; Kayser, F.; Kleinknecht, K.; Müller, A.-S.; Renk, B.; Sander, H.-G.; Schmeling, S.; Wachsmuth, H.; Zeitnitz, C.; Ziegler, T.; Bonissent, A.; Coyle, P.; Curtil, C.; Ealet, A.; Fouchez, D.; Payre, P.; Tilquin, A.; Ragusa, F.; David, A.; Dietl, H.; Ganis, G.; Hüttmann, K.; Lütjens, G.; Männer, W.; Moser, H.-G.; Settles, R.; Villegas, M.; Wolf, G.; Boucrot, J.; Callot, O.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jacholkowska, A.; Serin, L.; Veillet, J.-J.; Azzurri, P.; Bagliesi, G.; Boccali, T.; Foà, L.; Giammanco, A.; Giassi, A.; Ligabue, F.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Spagnolo, P.; Tenchini, R.; Venturi, A.; Verdini, P. G.; Awunor, O.; Blair, G. A.; Cowan, G.; Garcia-Bellido, A.; Green, M. G.; Medcalf, T.; Misiejuk, A.; Strong, J. A.; Teixeira-Dias, P.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Tomalin, I. R.; Ward, J. J.; Bloch-Devaux, B.; Boumediene, D.; Colas, P.; Fabbro, B.; Lançon, E.; Lemaire, M.-C.; Locci, E.; Perez, P.; Rander, J.; Tuchming, B.; Vallage, B.; Litke, A. M.; Taylor, G.; Booth, C. N.; Cartwright, S.; Combley, F.; Hodgson, P. N.; Lehto, M.; Thompson, L. F.; Böhrer, A.; Brandt, S.; Grupen, C.; Hess, J.; Ngac, A.; Prange, G.; Borean, C.; Giannini, G.; He, H.; Putz, J.; Rothberg, J.; Armstrong, S. R.; Berkelman, K.; Cranmer, K.; Ferguson, D. P. S.; Gao, Y.; González, S.; Hayes, O. J.; Hu, H.; Jin, S.; Kile, J.; McNamara, P. A.; Nielsen, J.; Pan, Y. B.; von Wimmersperg-Toeller, J. H.; Wiedenmann, W.; Wu, J.; Wu, S. L.; Wu, X.; Zobernig, G.; Dissertori, G.

    2005-01-01

    Bose Einstein correlations in W-pair decays are studied using data collected by the ALEPH detector at LEP at e+e- centre-of-mass energies from 183 to 209 GeV. The analysis is based on the comparison of WW→qq¯qq¯ events to “mixed” events constructed with the hadronic part of WW→qq¯ℓν events. The data are in agreement with the hypothesis that Bose Einstein correlations are present only for pions from the same W decay. The JETSET model with Bose Einstein correlations between pions from different W bosons is disfavoured.

  19. Integrability of an inhomogeneous nonlinear Schroedinger equation in Bose-Einstein condensates and fiber optics

    SciTech Connect

    Brugarino, Tommaso; Sciacca, Michele

    2010-09-15

    In this paper, we investigate the integrability of an inhomogeneous nonlinear Schroedinger equation, which has several applications in many branches of physics, as in Bose-Einstein condensates and fiber optics. The main issue deals with Painleve property (PP) and Liouville integrability for a nonlinear Schroedinger-type equation. Solutions of the integrable equation are obtained by means of the Darboux transformation. Finally, some applications on fiber optics and Bose-Einstein condensates are proposed (including Bose-Einstein condensates in three-dimensional in cylindrical symmetry).

  20. Universal Themes of Bose-Einstein Condensation

    NASA Astrophysics Data System (ADS)

    Proukakis, Nick P.; Snoke, David W.; Littlewood, Peter B.

    2017-04-01

    Foreword; List of contributors; Preface; Part I. Introduction: 1. Universality and Bose–Einstein condensation: perspectives on recent work D. W. Snoke, N. P. Proukakis, T. Giamarchi and P. B. Littlewood; 2. A history of Bose–Einstein condensation of atomic hydrogen T. Greytak and D. Kleppner; 3. Twenty years of atomic quantum gases: 1995–2015 W. Ketterle; 4. Introduction to polariton condensation P. B. Littlewood and A. Edelman; Part II. General Topics: Editorial notes; 5. The question of spontaneous symmetry breaking in condensates D. W. Snoke and A. J. Daley; 6. Effects of interactions on Bose–Einstein condensation R. P. Smith; 7. Formation of Bose–Einstein condensates M. J. Davis, T. M. Wright, T. Gasenzer, S. A. Gardiner and N. P. Proukakis; 8. Quenches, relaxation and pre-thermalization in an isolated quantum system T. Langen and J. Schmiedmayer; 9. Ultracold gases with intrinsic scale invariance C. Chin; 10. Berezinskii–Kosterlitz–Thouless phase of a driven-dissipative condensate N. Y. Kim, W. H. Nitsche and Y. Yamamoto; 11. Superfluidity and phase correlations of driven dissipative condensates J. Keeling, L. M. Sieberer, E. Altman, L. Chen, S. Diehl and J. Toner; 12. BEC to BCS crossover from superconductors to polaritons A. Edelman and P. B. Littlewood; Part III. Condensates in Atomic Physics: Editorial notes; 13. Probing and controlling strongly correlated quantum many-body systems using ultracold quantum gases I. Bloch; 14. Preparing and probing chern bands with cold atoms N. Goldman, N. R. Cooper and J. Dalibard; 15. Bose–Einstein condensates in artificial gauge fields L. J. LeBlanc and I. B. Spielman; 16. Second sound in ultracold atomic gases L. Pitaevskii and S. Stringari; 17. Quantum turbulence in atomic Bose–Einstein condensates N. G. Parker, A. J. Allen, C. F. Barenghi and N. P. Proukakis; 18. Spinor-dipolar aspects of Bose–Einstein condensation M. Ueda; Part IV. Condensates in Condensed Matter Physics: Editorial notes; 19

  1. Bose-Einstein condensation of dipolar excitons in quantum wells

    NASA Astrophysics Data System (ADS)

    Timofeev, V. B.; Gorbunov, A. V.

    2009-02-01

    The experiments on Bose-Einstein condensation (BEC) of dipolar (spatially-indirect) excitons in the lateral traps in GaAs/AlGaAs Schottky-diode heterostructures with double and single quantum wells are presented. The condensed part of dipolar excitons under detection in the far zone is placed in k-space in the range which is almost two orders of magnitude less than thermal exciton wave vector. BEC occurs spontaneously in a reservoir of thermalized excitons. Luminescence images of Bose-condensate of dipolar excitons exhibit along perimeter of circular trap axially symmetrical spatial structures of equidistant bright spots which strongly depend on excitation power and temperature. By means of two-beam interference experiments with the use of cw and pulsed photoexcitation it was found that the state of dipolar exciton Bose-condensate is spatially coherent and the whole patterned luminescence configuration in real space is described by a common wave function.

  2. Geometrical pumping with a Bose-Einstein condensate

    PubMed Central

    Lu, H.-I; Schemmer, M.; Aycock, L. M.; Genkina, D.; Sugawa, S.

    2016-01-01

    We realized a quantum geometric “charge” pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global – topological – properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exibits non-quantized charge pumping set by local – geometrical – properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wavepacket’s position in each unit cell, i.e., the polarization. PMID:27258857

  3. Dynamics of spinor Bose-Einstein condensate subject to dissipation

    NASA Astrophysics Data System (ADS)

    Man-Man, Pang; Ya-Jiang, Hao

    2016-04-01

    We investigate the internal dynamics of the spinor Bose-Einstein condensates subject to dissipation by solving the Lindblad master equation. It is shown that for the condensates without dissipation its dynamics always evolve along a specific orbital in the phase space of (n 0, θ) and display three kinds of dynamical properties including Josephson-like oscillation, self-trapping-like oscillation, and ‘running phase’. In contrast, the condensates subject to dissipation will not evolve along the specific dynamical orbital. If component-1 and component-(-1) dissipate at different rates, the magnetization m will not conserve and the system transits between different dynamical regions. The dynamical properties can be exhibited in the phase space of (n 0, θ, m). Project supported by the National Natural Science Foundation of China (Grant No. 11004007) and the Fundamental Research Funds for the Central Universities of China.

  4. Controlling rogue waves in inhomogeneous Bose-Einstein condensates.

    PubMed

    Loomba, Shally; Kaur, Harleen; Gupta, Rama; Kumar, C N; Raju, Thokala Soloman

    2014-05-01

    We present the exact rogue wave solutions of the quasi-one-dimensional inhomogeneous Gross-Pitaevskii equation by using similarity transformation. Then, by employing the exact analytical solutions we have studied the controllable behavior of rogue waves in the Bose-Einstein condensates context for the experimentally relevant systems. Additionally, we have also investigated the nonlinear tunneling of rogue waves through a conventional hyperbolic barrier and periodic barrier. We have found that, for the conventional nonlinearity barrier case, rogue waves are localized in space and time and get amplified near the barrier, while for the dispersion barrier case rogue waves are localized in space and propagating in time and their amplitude is reduced at the barrier location. In the case of the periodic barrier, the interesting dynamical features of rogue waves are obtained and analyzed analytically.

  5. Nonlinear waves in coherently coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Congy, T.; Kamchatnov, A. M.; Pavloff, N.

    2016-04-01

    We consider a quasi-one-dimensional two-component Bose-Einstein condensate subject to a coherent coupling between its components, such as realized in spin-orbit coupled condensates. We study how nonlinearity modifies the dynamics of the elementary excitations. The spectrum has two branches, which are affected in different ways. The upper branch experiences a modulational instability, which is stabilized by a long-wave-short-wave resonance with the lower branch. The lower branch is stable. In the limit of weak nonlinearity and small dispersion it is described by a Korteweg-de Vries equation or by the Gardner equation, depending on the value of the parameters of the system.

  6. Gaussian impurity moving through a Bose-Einstein superfluid

    NASA Astrophysics Data System (ADS)

    Pinsker, Florian

    2017-09-01

    In this paper a finite Gaussian impurity moving through an equilibrium Bose-Einstein condensate at T = 0 is studied. The problem can be described by a Gross-Pitaevskii equation, which is solved perturbatively. The analysis is done for systems of 2 and 3 spatial dimensions. The Bogoliubov equation solutions for the condensate perturbed by a finite impurity are calculated in the co-moving frame. From these solutions the total energy of the perturbed system is determined as a function of the width and the amplitude of the moving Gaussian impurity and its velocity. In addition we derive the drag force the finite sized impurity approximately experiences as it moves through the superfluid, which proves the existence of a superfluid phase for finite extensions of the impurities below the speed of sound. Finally we find that the force increases with velocity until an inflection point from which it decreases again in 2 and 3d.

  7. Momentum-space engineering of gaseous Bose-Einstein condensates

    SciTech Connect

    Edwards, Mark; Benton, Brandon; Heward, Jeffrey; Clark, Charles W.

    2010-12-15

    We show how the momentum distribution of gaseous Bose-Einstein condensates can be shaped by applying a sequence of standing-wave laser pulses. We present a theory, whose validity was demonstrated in an earlier experiment [L. Deng et al., Phys. Rev. Lett. 83, 5407 (1999)], of the effect of a two-pulse sequence on the condensate wavefunction in momentum space. We generalize the previous result to the case of N pulses of arbitrary intensity separated by arbitrary intervals and show how these parameters can be engineered to produce a desired final momentum distribution. We find that several momentum distributions, important in atom-interferometry applications, can be engineered with high fidelity with two or three pulses.

  8. Formation of molecules from a Cs Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Yurovsky, Vladimir

    2005-05-01

    An analysis was carried out of the recent Innsbruck experiments [1] on the conversion to molecules of an expanding Bose-Einstein condensate of Cs atoms, using an extremely weak Feshbach resonance. The theory, based on the approach of [2], takes into account atom-molecule and molecule-molecule deactivating collisions. It describes results observed for both ramping and switching schemes used in the experiments, including the exceptionally effective conversion achieved in the switching scheme. A fit of the theory to the experimental data provides an estimate of the resonance strength and the deactivation rates. 1. M. Mark, T. Kraemer, J. Herbig, C. Chin, H.-C. Nägerl, and R. Grimm, cond-mat/0409737. 2. V. A. Yurovsky and A. Ben-Reuven, Phys. Rev. A 70, 013613 (2004).

  9. Optical Devices for Cold Atoms and Bose-Einstein Condensates

    SciTech Connect

    Gaaloul, Naceur; Jaouadi, Amine; Telmini, Mourad; Pruvost, Laurence; Charron, Eric

    2007-09-19

    The manipulation of cold atoms with optical fields is a very promising technique for a variety of applications ranging from laser cooling and trapping to coherent atom transport and matter wave interferometry. Optical fields have also been proposed as interesting tools for quantum information processing with cold atoms. In this paper, we present a theoretical study of the dynamics of a cold {sup 87}Rb atomic cloud falling in the gravity field in the presence of two crossing dipole guides. The cloud is either deflected or split between the two branches of this guide. We explore the possibilities of optimization of this device and present preliminary results obtained in the case of zero-temperature dilute Bose-Einstein condensates.

  10. Stochastic phase slips in toroidal Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Snizhko, Kyrylo; Isaieva, Karyna; Kuriatnikov, Yevhenii; Bidasyuk, Yuriy; Vilchinskii, Stanislav; Yakimenko, Alexander

    2016-12-01

    Motivated by recent experiments we study the influence of thermal noise on the phase slips in toroidal Bose-Einstein condensates with a rotating weak link. We derive a generalized Arrhenius-like expression for the rate of stochastic phase slips. We develop a method to estimate the energy barrier separating different superflow states. The parameters at which the energy barrier disappears agree with the critical parameters for deterministic phase slips obtained from dynamics simulations, which confirms the validity of our energetic analysis. We reveal that adding thermal noise lowers the phase-slip threshold. However, the quantitative impact of the stochastic phase slips turns out to be too small to explain the significant discrepancy between theoretical and the experimental results.

  11. Kinetic approach to a relativistic Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Meistrenko, Alex; van Hees, Hendrik; Zhou, Kai; Greiner, Carsten

    2016-03-01

    We apply a Boltzmann approach to the kinetic regime of a relativistic Bose-Einstein condensate of scalar bosons by decomposing the one-particle distribution function in a condensate part and a nonzero momentum part of excited modes, leading to a coupled set of evolution equations which are then solved efficiently with an adaptive higher order Runge-Kutta scheme. We compare our results to the partonic cascade Monte Carlo simulation BAMPS for a critical but far from equilibrium case of massless bosons. Motivated by the color glass condensate initial conditions in QCD with a strongly overpopulated initial glasma state, we also discuss the time evolution starting from an overpopulated initial distribution function of massive scalar bosons. In this system a self-similar evolution of the particle cascade with a nonrelativistic turbulent scaling in the infrared sector is observed as well as a relativistic exponent for the direct energy cascade, confirming a weak wave turbulence in the ultraviolet region.

  12. Bose-Einstein condensation in a QUIC trap

    NASA Astrophysics Data System (ADS)

    Lu, B. L.; van Wijngaarden, W.

    2004-02-01

    The apparatus and procedure required to generate a pure Bose-Einstein condensate (BEC) consisting of about half a million Rb-87 atoms at a temperature of <60 nK with a phase density of >54 is described. The atoms are first laser cooled in a vapour cell magneto-optical trap (MOT) and subsequently transferred to an ultra-low pressure MOT. The atoms are loaded into a QUIC trap consisting of a pair of quadrupole coils and a Ioffe coil that generates a small finite magnetic field at the trap energy minimum to suppress Majorana transitions. Evaporation induced by an RF field lowers the temperature permitting the transition to BEC to be observed by monitoring the free expansion of the atoms after the trapping fields have been switched off.

  13. Stabilization of ring dark solitons in Bose-Einstein condensates

    DOE PAGES

    Wang, Wenlong; Kevrekidis, P. G.; Carretero-González, R.; ...

    2015-09-14

    Earlier work has shown that ring dark solitons in two-dimensional Bose-Einstein condensates are generically unstable. In this work, we propose a way of stabilizing the ring dark soliton via a radial Gaussian external potential. We investigate the existence and stability of the ring dark soliton upon variations of the chemical potential and also of the strength of the radial potential. Numerical results show that the ring dark soliton can be stabilized in a suitable interval of external potential strengths and chemical potentials. Furthermore, we also explore different proposed particle pictures considering the ring as a moving particle and find, wheremore » appropriate, results in very good qualitative and also reasonable quantitative agreement with the numerical findings.« less

  14. Quantized supercurrent decay in an annular Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Moulder, Stuart; Beattie, Scott; Smith, Robert P.; Tammuz, Naaman; Hadzibabic, Zoran

    2012-07-01

    We study the metastability and decay of multiply charged superflow in a ring-shaped atomic Bose-Einstein condensate. Supercurrent corresponding to a giant vortex with topological charge up to q=10 is phase imprinted optically and detected both interferometrically and kinematically. We observe q=3 superflow persisting for up to a minute and clearly resolve a cascade of quantized steps in its decay. These stochastic decay events, associated with vortex-induced 2π phase slips, correspond to collective jumps of atoms between discrete q values. We demonstrate the ability to detect quantized rotational states with >99% fidelity, which allows a detailed quantitative study of time-resolved phase-slip dynamics. We find that the supercurrent decays rapidly if the superflow speed exceeds a critical velocity in good agreement with numerical simulations, and we also observe rare stochastic phase slips for superflow speeds below the critical velocity.

  15. Stabilization of ring dark solitons in Bose-Einstein condensates

    SciTech Connect

    Wang, Wenlong; Kevrekidis, P. G.; Carretero-González, R.; Frantzeskakis, D. J.; Kaper, Tasso J.; Ma, Manjun

    2015-09-14

    Earlier work has shown that ring dark solitons in two-dimensional Bose-Einstein condensates are generically unstable. In this work, we propose a way of stabilizing the ring dark soliton via a radial Gaussian external potential. We investigate the existence and stability of the ring dark soliton upon variations of the chemical potential and also of the strength of the radial potential. Numerical results show that the ring dark soliton can be stabilized in a suitable interval of external potential strengths and chemical potentials. Furthermore, we also explore different proposed particle pictures considering the ring as a moving particle and find, where appropriate, results in very good qualitative and also reasonable quantitative agreement with the numerical findings.

  16. Entropy Production Within a Pulsed Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Heinisch, Christoph; Holthaus, Martin

    2016-10-01

    We suggest to subject anharmonically trapped Bose-Einstein condensates to sinusoidal forcing with a smooth, slowly changing envelope, and to measure the coherence of the system after such pulses. In a series of measurements with successively increased maximum forcing strength, one then expects an adiabatic return of the condensate to its initial state as long as the pulses remain sufficiently weak. In contrast, once the maximum driving amplitude exceeds a certain critical value there should be a drastic loss of coherence, reflecting significant heating induced by the pulse. This predicted experimental signature is traced to the loss of an effective adiabatic invariant, and to the ensuing breakdown of adiabatic motion of the system's Floquet state when the many-body dynamics become chaotic. Our scenario is illustrated with the help of a two-site model of a forced bosonic Josephson junction, but should also hold for other, experimentally accessible configurations.

  17. Moving impurity in an inhomogenous Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Mathew, Ranchu; Tiesinga, Eite

    2016-05-01

    We study the dynamics of a non-uniform Bose-Einstein condensate (BEC) under the influence of a moving weak point-like impurity. When the condensate density varies slowly compared to its healing length the critical velocity of the impurity, beyond which the condensate becomes unstable, can be calculated using the Local Density Approximation (LDA). This critical velocity corresponds to the smallest local sound speed. The LDA breaks down when the length scale of density variations is of the order of the healing length. We have calculated corrections to the critical velocity in this regime as an asymptotic expansion in the size of the BEC. We also discuss the experimental implications of our calculations by studying the stability of the atomic analogue of a Superconducting Quantum Interference Device (SQUID). The atom-SQUID consists of a BEC in a ring trap with rotating barrier. The impurity corresponds to imperfections in the ring trap.

  18. Kinetic approach to a relativistic Bose-Einstein condensate.

    PubMed

    Meistrenko, Alex; van Hees, Hendrik; Zhou, Kai; Greiner, Carsten

    2016-03-01

    We apply a Boltzmann approach to the kinetic regime of a relativistic Bose-Einstein condensate of scalar bosons by decomposing the one-particle distribution function in a condensate part and a nonzero momentum part of excited modes, leading to a coupled set of evolution equations which are then solved efficiently with an adaptive higher order Runge-Kutta scheme. We compare our results to the partonic cascade Monte Carlo simulation BAMPS for a critical but far from equilibrium case of massless bosons. Motivated by the color glass condensate initial conditions in QCD with a strongly overpopulated initial glasma state, we also discuss the time evolution starting from an overpopulated initial distribution function of massive scalar bosons. In this system a self-similar evolution of the particle cascade with a nonrelativistic turbulent scaling in the infrared sector is observed as well as a relativistic exponent for the direct energy cascade, confirming a weak wave turbulence in the ultraviolet region.

  19. Spatial structure of a collisionally inhomogeneous Bose-Einstein condensate

    SciTech Connect

    Li, Fei; Zhang, Dongxia; Rong, Shiguang; Xu, Ying

    2013-11-15

    The spatial structure of a collisionally inhomogeneous Bose-Einstein condensate (BEC) in an optical lattice is studied. A spatially dependent current with an explicit analytic expression is found in the case with a spatially dependent BEC phase. The oscillating amplitude of the current can be adjusted by a Feshbach resonance, and the intensity of the current depends heavily on the initial and boundary conditions. Increasing the oscillating amplitude of the current can force the system to pass from a single-periodic spatial structure into a very complex state. But in the case with a constant phase, the spatially dependent current disappears and the Melnikov chaotic criterion is obtained via a perturbative analysis in the presence of a weak optical lattice potential. Numerical simulations show that a strong optical lattice potential can lead BEC atoms to a state with a chaotic spatial distribution via a quasiperiodic route.

  20. Bose-Einstein condensation in liquid 4He under pressure

    SciTech Connect

    Glyde, Henry R; Omar Diallo, Souleymane; Azuah, Richard T; Kirichek, Oleg; Taylor, Jon W.

    2011-01-01

    We present neutron scattering measurements of Bose-Einstein condensation, the atomic momen- tum distribution and Final State effects in liquid 4He under pressure. The condensate fraction at low temperature is found to decrease from n0 = 7.25 0.75% at SVP (p 0) to n0 = 3.2 0.75% at pressure p = 24 bar. This indicates an n0 = 3.0% in the liquid at the liquid/solid co-existence line (p = 25.3 bar). The atomic momentum distribution n(k) has high occupation of low k states and differs significantly from a Gaussian (e.g. a classical n(k)). Both n(k) and the Final state function broaden with increasing pressure, reflecting the increased localization of the 4He in space under increased pressure.

  1. Bound-state signatures in quenched Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Corson, John P.; Bohn, John L.

    2015-01-01

    We investigate the dynamics of a homogenous Bose-Einstein condensate (BEC) following a sudden quench of the scattering length. Our focus is the time evolution of short-range correlations via the dynamical contact. We compute the dynamics using a combination of two- and many-body models and we propose an intuitive connection between them that unifies their short-time, short-range predictions. Our two-body models are exactly solvable and, when properly calibrated, lead to analytic formulas for the contact dynamics. Immediately after the quench, the contact exhibits strong oscillations at the frequency of the two-body bound state. These oscillations are large in amplitude and their time average is typically much larger than the Bogoliubov prediction. The condensate fraction shows similar oscillations, whose amplitude we are able to estimate. These results demonstrate the importance of including the bound state in descriptions of diabatically quenched BEC experiments.

  2. Mode locking of a driven Bose-Einstein condensate

    SciTech Connect

    Nicolin, Alexandru I.; Jensen, Mogens H.; Carretero-Gonzalez, R.

    2007-03-15

    We consider the dynamics of a driven Bose-Einstein condensate with positive scattering length. Employing an accustomed variational treatment we show that when the scattering length is time modulated as a(1+{epsilon} sin[{omega}(t)t]), where {omega}(t) increases linearly in time, i.e., {omega}(t)={gamma}t, the response frequency of the condensate locks to the eigenfrequency for small values of {epsilon} and {gamma}. A simple analytical model is presented which explains this phenomenon by mapping it to an auto-resonance, i.e., close to resonance the reduced equations describing the collective behavior of the condensate are equivalent to those of a virtual particle trapped in a finite-depth energy minimum of an effective potential.

  3. Dynamical quantum phase transition of a two-component Bose-Einstein condensate in an optical lattice

    SciTech Connect

    Collin, Anssi; Martikainen, Jani-Petri; Larson, Jonas

    2010-01-15

    We study the dynamics of a two-component Bose-Einstein condensate where the two components are coupled via an optical lattice. In particular, we focus on the dynamics as one drives the system through a critical point of a first-order phase transition characterized by a jump in the internal populations. Solving the time-dependent Gross-Pitaevskii equation, we analyze the breakdown of adiabaticity, impact of nonlinear atom-atom scattering, and role of a harmonic trapping potential. Our findings demonstrate that the phase transition is resilient to both contact interaction between atoms and external trapping confinement.

  4. Path-Integral Monte Carlo Study on a Droplet of a Dipolar Bose-Einstein Condensate Stabilized by Quantum Fluctuation

    NASA Astrophysics Data System (ADS)

    Saito, Hiroki

    2016-05-01

    Motivated by recent experiments [H. Kadau et al., http://doi.org/10.1038/nature16485, Nature (London) 530, 194 (2016); I. Ferrier-Barbut et al., http://arxiv.org/abs/1601.03318, arXiv:1601.03318] and theoretical prediction (F. Wächtler and L. Santos, http://arxiv.org/abs/1601.04501, arXiv:1601.04501), the ground state of a dysprosium Bose-Einstein condensate with strong dipole-dipole interaction is studied by the path-integral Monte Carlo method. It is shown that quantum fluctuation can stabilize the condensate against dipolar collapse.

  5. Multimode mean-field model for the quantum phase transition of a Bose-Einstein condensate in an optical resonator

    NASA Astrophysics Data System (ADS)

    Kónya, G.; Szirmai, G.; Domokos, P.

    2011-11-01

    We develop a mean-field model describing the Hamiltonian interaction of ultracold atoms and the optical field in a cavity. The Bose-Einstein condensate is properly defined by means of a grand-canonical approach. The model is efficient because only the relevant excitation modes are taken into account. However, the model goes beyond the two-mode subspace necessary to describe the self-organization quantum phase transition observed recently. We calculate all the second-order correlations of the coupled atom field and radiation field hybrid bosonic system, including the entanglement between the two types of fields.

  6. Bose-Einstein condensation of particle-hole pairs in ultracold fermionic atoms trapped within optical lattices.

    PubMed

    Lee, Chaohong

    2004-09-17

    We investigate the Bose-Einstein condensation (BEC, superfluidity) of particle-hole pairs in ultracold fermionic atoms with repulsive interactions and arbitrary polarization, which are trapped within optical lattices. In the strongly repulsive limit, the dynamics of particle-hole pairs can be described by a hard-core Bose-Hubbard model. The insulator-superfluid and charge-density-wave- (CDW) superfluid phase transitions can be induced by decreasing and increasing the potential depths with controlling the trapping laser intensity, respectively. The parameter and polarization dependence of the critical temperatures for the ordered states (BEC and/or CDW) are discussed simultaneously.

  7. Quantum tunneling time of a Bose-Einstein condensate traversing through a laser-induced potential barrier

    SciTech Connect

    Duan Zhenglu; Fan Bixuan; Yuan Chunhua; Zhang Weiping; Cheng Jing; Zhu Shiyao

    2010-05-15

    We theoretically study the effect of atomic nonlinearity on the tunneling time in the case of an atomic Bose-Einstein condensate (BEC) traversing the laser-induced potential barrier. The atomic nonlinearity is controlled to appear only in the region of the barrier by employing the Feshbach resonance technique to tune interatomic interaction in the tunneling process. Numerical simulation shows that the atomic nonlinear effect dramatically changes the tunneling behavior of the BEC matter wave packet and results in the violation of the Hartman effect and the occurrence of negative tunneling time.

  8. Einstein-Podolsky-Rosen-entangled Bose-Einstein condensates in state-dependent potentials: A dynamical study

    NASA Astrophysics Data System (ADS)

    Kurkjian, Hadrien; Pawłowski, Krzysztof; Sinatra, Alice

    2017-07-01

    We study the generation of nonlocal correlations by atomic interactions in a pair of bimodal Bose-Einstein condensates in state-dependent potentials including spatial dynamics. The wave functions of the four components are described by combining a Fock state expansion with a time-dependent Hartree-Fock ansatz so that both the spatial dynamics and the local and nonlocal quantum correlations are accounted for. We find that despite the spatial dynamics, our protocol generates enough nonlocal entanglement to perform an Einstein-Podolsky-Rosen steering experiment with two spatially separated condensates of a few thousand atoms.

  9. Dynamics of quantum vortices in a quasi-two-dimensional Bose-Einstein condensate with two "holes"

    NASA Astrophysics Data System (ADS)

    Ruban, V. P.

    2017-04-01

    The dynamics of interacting quantum vortices in a quasi-two-dimensional spatially inhomogeneous Bose-Einstein condensate, whose equilibrium density vanishes at two points of the plane with a possible presence of an immobile vortex with a few circulation quanta at each point, has been considered in a hydrodynamic approximation. A special class of density profiles has been chosen, so that it proves possible to calculate analytically the velocity field produced by point vortices. The equations of motion have been given in a noncanonical Hamiltonian form. The theory has been generalized to the case where the condensate forms a curved quasi-two-dimensional shell in the three-dimensional space.

  10. Evolution and dynamical properties of Bose-Einstein condensate dark matter stars

    NASA Astrophysics Data System (ADS)

    Madarassy, Eniko J. M.; Toth, Viktor T.

    2015-02-01

    Using recently developed nonrelativistic numerical simulation code, we investigate the stability properties of compact astrophysical objects that may be formed due to the Bose-Einstein condensation of dark matter. Once the temperature of a boson gas is less than the critical temperature, a Bose-Einstein condensation process can always take place during the cosmic history of the Universe. Because of dark matter accretion, a Bose-Einstein condensed core can also be formed inside massive astrophysical objects such as neutron stars or white dwarfs, for example. Numerically solving the Gross-Pitaevskii-Poisson system of coupled differential equations, we demonstrate, with longer simulation runs, that within the computational limits of the simulation the objects we investigate are stable. Physical properties of a self-gravitating Bose-Einstein condensate are examined both in nonrotating and rotating cases.

  11. Bose-Einstein condensation in an ultra-hot gas of pumped magnons.

    PubMed

    Serga, Alexander A; Tiberkevich, Vasil S; Sandweg, Christian W; Vasyuchka, Vitaliy I; Bozhko, Dmytro A; Chumak, Andrii V; Neumann, Timo; Obry, Björn; Melkov, Gennadii A; Slavin, Andrei N; Hillebrands, Burkard

    2014-03-11

    Bose-Einstein condensation of quasi-particles such as excitons, polaritons, magnons and photons is a fascinating quantum mechanical phenomenon. Unlike the Bose-Einstein condensation of real particles (like atoms), these processes do not require low temperatures, since the high densities of low-energy quasi-particles needed for the condensate to form can be produced via external pumping. Here we demonstrate that such a pumping can create remarkably high effective temperatures in a narrow spectral region of the lowest energy states in a magnon gas, resulting in strikingly unexpected transitional dynamics of Bose-Einstein magnon condensate: the density of the condensate increases immediately after the external magnon flow is switched off and initially decreases if it is switched on again. This behaviour finds explanation in a nonlinear 'evaporative supercooling' mechanism that couples the low-energy magnons overheated by pumping with all the other thermal magnons, removing the excess heat, and allowing Bose-Einstein condensate formation.

  12. The Evolution of Hyperedge Cardinalities and Bose-Einstein Condensation in Hypernetworks.

    PubMed

    Guo, Jin-Li; Suo, Qi; Shen, Ai-Zhong; Forrest, Jeffrey

    2016-09-27

    To depict the complex relationship among nodes and the evolving process of a complex system, a Bose-Einstein hypernetwork is proposed in this paper. Based on two basic evolutionary mechanisms, growth and preference jumping, the distribution of hyperedge cardinalities is studied. The Poisson process theory is used to describe the arrival process of new node batches. And, by using the Poisson process theory and a continuity technique, the hypernetwork is analyzed and the characteristic equation of hyperedge cardinalities is obtained. Additionally, an analytical expression for the stationary average hyperedge cardinality distribution is derived by employing the characteristic equation, from which Bose-Einstein condensation in the hypernetwork is obtained. The theoretical analyses in this paper agree with the conducted numerical simulations. This is the first study on the hyperedge cardinality in hypernetworks, where Bose-Einstein condensation can be regarded as a special case of hypernetworks. Moreover, a condensation degree is also discussed with which Bose-Einstein condensation can be classified.

  13. Two characteristic temperatures for a Bose-Einstein condensate of a finite number of particles

    SciTech Connect

    Idziaszek, Z.; Rzazewski, K.

    2003-09-01

    We consider two characteristic temperatures for a Bose-Einstein condensate, which are related to certain properties of the condensate statistics. We calculate them for an ideal gas confined in power-law traps and show that they approach the critical temperature in the limit of large number of particles. The considered characteristic temperatures can be useful in the studies of Bose-Einstein condensates of a finite number of atoms indicating the point of a phase transition.

  14. Two types of phase diagrams for two-species Bose-Einstein condensates and the combined effect of the parameters

    NASA Astrophysics Data System (ADS)

    Li, Z. B.; Liu, Y. M.; Yao, D. X.; Bao, C. G.

    2017-07-01

    Under the Thomas-Fermi approximation, an approach is proposed to solve the coupled Gross-Pitaevskii equations (CGP) for the two-species Bose-Einstein condensate analytically. The essence of this approach is to find out the building blocks to build the solution. By introducing the weighted strengths, relatively simpler analytical solutions have been obtained. A number of formulae have been deduced to relate the parameters when the system is experimentally tuned at various status. These formulae demonstrate the combined effect of the parameters, and are useful for the evaluation of their magnitudes. The whole parameter space is divided into zones, where each supports a specific phase. All the boundaries separating these zones have analytical expressions. Based on the division, the phase diagrams against any set of parameters can be plotted. In addition, by introducing a model for the asymmetric states, the total energies of the lowest symmetric and asymmetric states have been compared. Thereby, in which case the former will be replaced by the latter has been evaluated. The CGP can be written in a matrix form. For repulsive inter-species interaction V AB , when the parameters vary and cross over the singular point of the matrix, a specific state transition will happen and the total energy of the lowest symmetric state will increase remarkably. This provides an excellent opportunity for the lowest asymmetric state to emerge as the ground state. For attractive V AB , when the parameters tend to a singular point, the system will tend to collapse. The effects caused by the singular points have been particularly studied.

  15. Impact of inelastic processes on the chaotic dynamics of a Bose-Einstein condensate trapped into a moving optical lattice

    NASA Astrophysics Data System (ADS)

    Tchatchueng, Sylvin; Siewe Siewe, Martin; Marie Moukam Kakmeni, François; Tchawoua, Clément

    2017-03-01

    We investigate the dynamics of a Bose-Einstein condensate with attractive two-body and repulsive three-body interactions between atoms trapped into a moving optical lattice and subjected to some inelastic processes (a linear atomic feeding and two dissipative terms related to dipolar relaxation and three-body recombination). We are interested in finding out how the nonconservative terms mentioned above act on the dynamical behaviour of the condensate, and how they can be used in the control of possible chaotic dynamics. Seeking the wave function of condensate on the form of Bloch waves, we notice that the real amplitude of the condensate is governed by an integro-differential equation. As theoretical tool of prediction of homoclinic and heteroclinic chaos, we use the Melnikov method, which provides two Melnikov functions related to homoclinic and heteroclinic bifurcations. Applying the Melnikov criterion, some regions of instability are plotted in the parameter space and reveal complex dynamics (solitonic stable solutions, weak and strong instabilities leading to collapse, growth-collapse cycles and finally to chaotic oscillations). It comes from some parameter space that coupling the optical intensity and parameters related to atomic feeding and atomic losses (dissipations) as control parameters can help to reduce or annihilate chaotic behaviours of the condensate. Moreover, the theoretical study reveals that there is a certain ratio between the atomic feeding parameter and the parameters related to the dissipation for the occurrence of chaotic oscillations in the dynamics of condensate. The theoretical predictions are verified by numerical simulations (Poincaré sections), and there is a certain reliability of our analytical treatment.

  16. Stationary States and Modulational Instability of Coupled Two-Component Bose-Einstein Condensates in a Ring Trap

    NASA Astrophysics Data System (ADS)

    Deng, Hai-Ming; Zhong, Hong-Hua; Huang, Jia-Hao; Dai, Hui; Yao, Min; Huang, Xiao-Yi

    2015-08-01

    We investigate modulational instability (MI) of a coupled two-component Bose-Einstein condensates in a rotating ring trap. The excitation spectrum and the MI condition of the system are presented analytically. We find that the coupling between the two components strongly modifies the MI condition, and the MI condition is phase-dependent. Furthermore, we discuss the effect of MI on both density excitation and spin excitation. If the inter- and intra-component interaction strengths are all equal, the MI causes density excitation but not spin excitation, and if the inter- and intra-component interaction strengths are different, the MI causes both density excitation and spin excitation. Our results provide a promising approach for controlling the stability and excitation of a rotating two-component Bose-Einstein condensates by modulating its coupling strength and interaction strength. Supported by the National Natural Science Foundation of China under Grant No. 11465008, the Hunan Provincial Natural Science Foundation under Grant No. 2015JJ2114, the Scientific Research Fund of Hunan Provincial Education Department under Grant Nos. 14A118, 13C881, Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province, and Science Research Foundation of Xiangnan University under Grant No. 2012-126(41)

  17. Solitons and solitary vortices in pancake-shaped Bose-Einstein condensates

    SciTech Connect

    Salasnich, Luca; Malomed, Boris A.

    2009-05-15

    We study fundamental and vortical solitons in disk-morphed Bose-Einstein condensates (BECs) subject to strong confinement along the axial direction. Starting from the three-dimensional (3D) Gross-Pitaevskii equation (GPE), we proceed to an effective two-dimensional (2D) nonpolynomial Schroedinger equation (NPSE) derived by means of the integration over the axial coordinate. Results produced by the latter equation are in very good agreement with those obtained from the full 3D GPE, including cases when the formal 2D equation with the cubic nonlinearity is unreliable. The 2D NPSE is used to predict the density profiles and dynamical stability of repulsive and attractive BECs with zero and finite topological charges in various planar trapping configurations, including the axisymmetric harmonic confinement and one-dimensional periodic potential. In particular, we find a stable dynamical regime that was not reported before, viz., periodic splitting and recombination of trapped vortices with topological charges 2 or 3 in the self-attractive BEC.

  18. Winding up superfluid in a torus via Bose Einstein condensation

    PubMed Central

    Das, Arnab; Sabbatini, Jacopo; Zurek, Wojciech H.

    2012-01-01

    Phase transitions are usually treated as equilibrium phenomena, which yields telltale universality classes with scaling behavior of relaxation time and healing length. However, in second-order phase transitions relaxation time diverges near the critical point (“critical slowing down”). Therefore, every such transition traversed at a finite rate is a non-equilibrium process. Kibble-Zurek mechanism (KZM) captures this basic physics, predicting sizes of domains – fragments of broken symmetry – and the density of topological defects, long-lived relics of symmetry breaking that can survive long after the transition. To test KZM we simulate Bose-Einstein condensation in a ring using stochastic Gross-Pitaevskii equation and show that BEC formation can spontaneously generate quantized circulation of the newborn condensate. The magnitude of the resulting winding numbers and the time-lag of BEC density growth – both experimentally measurable – follow scalings predicted by KZM. Our results may also facilitate measuring the dynamical critical exponent for the BEC transition. PMID:22500209

  19. Atom loss resonances in a Bose-Einstein condensate.

    PubMed

    Langmack, Christian; Smith, D Hudson; Braaten, Eric

    2013-07-12

    Atom loss resonances in ultracold trapped atoms have been observed at scattering lengths near atom-dimer resonances, at which Efimov trimers cross the atom-dimer threshold, and near two-dimer resonances, at which universal tetramers cross the dimer-dimer threshold. We propose a new mechanism for these loss resonances in a Bose-Einstein condensate of atoms. As the scattering length is ramped to the large final value at which the atom loss rate is measured, the time-dependent scattering length generates a small condensate of shallow dimers coherently from the atom condensate. The coexisting atom and dimer condensates can be described by a low-energy effective field theory with universal coefficients that are determined by matching exact results from few-body physics. The classical field equations for the atom and dimer condensates predict narrow enhancements in the atom loss rate near atom-dimer resonances and near two-dimer resonances due to inelastic dimer collisions.

  20. Interferometry with independently prepared Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Wasak, T.; Szańkowski, P.; Chwedeńczuk, J.

    2015-04-01

    Whenever the value of an unknown parameter θ is extracted from a series of experiments, the result is inevitably burdened by the uncertainty Δ θ . If the system that is the subject of measurement consists of unentangled particles, this uncertainty is bounded by the shot-noise limit. To overcome this limitation, it is necessary to use a properly entangled state, which is usually prepared in a dedicated procedure. We show that quantum correlations arising from the indistinguishability of bosons are a sufficient resource for the sub-shot-noise interferometry. To this end, we consider an interferometer, which operates on two independently prepared Bose-Einstein condensates with fluctuating numbers of particles. We calculate the sensitivity obtained from the measurement of the number of atoms and compare it with the ultimate achievable bound. Our main conclusion is that even in the presence of major atom number fluctuations, an interferometer operating on two independently prepared condensates can give very high precision. These observations indicate a new possibility for an interferometer operating below the shot-noise limit.

  1. Squeezing and entanglement in a Bose-Einstein condensate.

    PubMed

    Estève, J; Gross, C; Weller, A; Giovanazzi, S; Oberthaler, M K

    2008-10-30

    Entanglement, a key feature of quantum mechanics, is a resource that allows the improvement of precision measurements beyond the conventional bound attainable by classical means. This results in the standard quantum limit, which is reached in today's best available sensors of various quantities such as time and position. Many of these sensors are interferometers in which the standard quantum limit can be overcome by using quantum-entangled states (in particular spin squeezed states) at the two input ports. Bose-Einstein condensates of ultracold atoms are considered good candidates to provide such states involving a large number of particles. Here we demonstrate spin squeezed states suitable for atomic interferometry by splitting a condensate into a few parts using a lattice potential. Site-resolved detection of the atoms allows the measurement of the atom number difference and relative phase, which are conjugate variables. The observed fluctuations imply entanglement between the particles, a resource that would allow a precision gain of 3.8 dB over the standard quantum limit for interferometric measurements.

  2. Stability of persistent currents in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Yakimenko, A. I.; Isaieva, K. O.; Vilchinskii, S. I.; Weyrauch, M.

    2013-11-01

    Motivated by a recent experiment [Beattie, Moulder, Fletcher, and Hadzibabic, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.110.025301 110, 025301 (2013)], we study the superflow of atomic spinor Bose-Einstein condensates optically trapped in a ring-shaped geometry. Within a dissipative mean-field approach we simulate a two-component condensate in conditions adapted to the experiment. In qualitative agreement with the experimental findings, we observe stable superflow if the spin-population imbalance is above some well-defined threshold value. Below the stability threshold the persistent currents with higher-order circulation decay in quantized steps, and the vortex lines escape from the center of the ring through dynamically created “weak links” in the condensate annulus. These regions with reduced density of one spin component are filled by atoms of the other component. The vortices then leave the ring-shaped high-density region of the condensate and finally decay into elementary excitations.

  3. Counterdiabatic vortex pump in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ollikainen, T.; Masuda, S.; Möttönen, M.; Nakahara, M.

    2017-01-01

    Topological phase imprinting is a well-established technique for deterministic vortex creation in spinor Bose-Einstein condensates of alkali-metal atoms. It was recently shown that counterdiabatic quantum control may accelerate vortex creation in comparison to the standard adiabatic protocol and suppress the atom loss due to nonadiabatic transitions. Here we apply this technique, assisted by an optical plug, for vortex pumping to theoretically show that sequential phase imprinting up to 20 cycles generates a vortex with a very large winding number. Our method significantly increases the fidelity of the pump for rapid pumping compared to the case without the counterdiabatic control, leading to the highest angular momentum per particle reported to date for the vortex pump. Our studies are based on numerical integration of the three-dimensional multicomponent Gross-Pitaevskii equation, which conveniently yields the density profiles, phase profiles, angular momentum, and other physically important quantities of the spin-1 system. Our results motivate the experimental realization of the vortex pump and studies of the rich physics it involves.

  4. Atom-molecule coherence in a Bose-Einstein condensate.

    PubMed

    Donley, Elizabeth A; Claussen, Neil R; Thompson, Sarah T; Wieman, Carl E

    2002-05-30

    Recent advances in the precise control of ultracold atomic systems have led to the realisation of Bose Einstein condensates (BECs) and degenerate Fermi gases. An important challenge is to extend this level of control to more complicated molecular systems. One route for producing ultracold molecules is to form them from the atoms in a BEC. For example, a two-photon stimulated Raman transition in a (87)Rb BEC has been used to produce (87)Rb(2) molecules in a single rotational-vibrational state, and ultracold molecules have also been formed through photoassociation of a sodium BEC. Although the coherence properties of such systems have not hitherto been probed, the prospect of creating a superposition of atomic and molecular condensates has initiated much theoretical work. Here we make use of a time-varying magnetic field near a Feshbach resonance to produce coherent coupling between atoms and molecules in a (85)Rb BEC. A mixture of atomic and molecular states is created and probed by sudden changes in the magnetic field, which lead to oscillations in the number of atoms that remain in the condensate. The oscillation frequency, measured over a large range of magnetic fields, is in excellent agreement with the theoretical molecular binding energy, indicating that we have created a quantum superposition of atoms and diatomic molecules two chemically different species.

  5. Quantum hydrodynamics in dilute-gas Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Engels, Peter

    2012-10-01

    The peculiar dynamics of superfluids are a fascinating research topic. Since the first generation of a dilute gas Bose-Einstein condensate (BEC) in 1995, quantum degenerate atomic gases have taken the investigation of quantum hydrodynamics to a new level. The atomic physics toolbox has grown tremendously and now provides unique and powerful ways to explore nonlinear quantum systems. As an example, pioneering results have recently revealed that the counterflow between two superfluids can be used as a well controlled tool to access the rich dynamics of vector systems. New structures, such as beating dark-dark solitons which only exist in multicomponent systems and have never been observed before, can now be realized in the lab for the first time. Furthermore, the field of nonlinear quantum hydrodynamics is entering new regimes by exploiting Raman dressing as a tool to directly modify the dispersion relation. This leads to the generation of spin-orbit coupled BECs, artificial gauge fields, etc. that are currently receiving tremendous interest due to their parallels to complex condensed-matter systems. Studies of quantum hydrodynamics help to develop a profound understanding of nonlinear quantum dynamics, which is not only of fundamental interest but also of eminent importance for future technological applications, e.g. in telecommunication applications using optical solitons in fibers. This talk will showcase some ``classic'' hallmark results and highlight recent advances from the forefront of the field.

  6. Bose-Einstein condensation in low dimensional layered structures

    NASA Astrophysics Data System (ADS)

    Salas, Patricia; Solis, M. A.

    2008-03-01

    Bose-Einstein condensation critical temperature, among other thermodynamic properties are reported for an ideal boson gas inside layered structures created by trapping potential of the Kronig-Penney type. We start with a big box where we introduce the Kronig-Penney potential in three directions to get a honey comb of cubes of side a size and walls of variable penetrability (P=mV0ab/^2), with bosons instead of bees. We are able to reduce the dimensions of the cubes to simulate bosons inside quantum dots. The critical temperature, starting from that of an ideal boson gas inside the big box, decreases as the small cube wall impenetrability increases arriving to a tiny but different from zero when the penetrability is zero (P-->∞). We also calculate the internal energy and the specific heat, and compare them to the ones obtained for the case of the same Kronig-Penney potential in one direction (simulating layers), and two directions (nanotubes).

  7. Early stage of Superradiance from Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Buchmann, Lukas

    2011-05-01

    We investigate the dynamics of matter and optical waves at the early stage of superradiant Rayleigh scattering from Bose-Einstein condensates, an instance of four-wave-mixing of matter and optical waves. Our analysis is within a spatially dependent model which treats the matter-waves as well as the optical end-fire modes quantum mechanically and is capable of providing analytic solutions for the operators of interest. In particular, we study the statistical properties of the outgoing scattered light which provide insight into the rich internal dynamics of the system at this early stage. Furthermore, we investigate coherence properties of pairs of counter propagating atomic sidemodes produced during the process. It is shown that these clouds exhibit long-range spatial coherence and strong nonclassical density cross-correlations due to entanglement between the clouds. These findings make this scheme a promising candidate for the production of highly directional nonclassically correlated atomic pulses. Our prediction of number difference squeezing between the clouds was observed in another instance of a four-wave mixing process using metastable helium. Work performed at IESL-FORTH in Crete, Greece

  8. Magnetic solitons in Rabi-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Qu, Chunlei; Tylutki, Marek; Stringari, Sandro; Pitaevskii, Lev P.

    2017-03-01

    We study magnetic solitons, solitary waves of spin polarization (i.e., magnetization), in binary Bose-Einstein condensates in the presence of Rabi coupling. We show that the system exhibits two types of magnetic solitons, called 2 π and 0 π solitons, characterized by a different behavior of the relative phase between the two spin components. 2 π solitons exhibit a 2 π jump of the relative phase, independent of their velocity, the static domain wall explored by Son and Stephanov being an example of such 2 π solitons with vanishing velocity and magnetization. 0 π solitons instead do not exhibit any asymptotic jump in the relative phase. Systematic results are provided for both types of solitons in uniform matter. Numerical calculations in the presence of a one-dimensional harmonic trap reveal that a 2 π soliton evolves in time into a 0 π soliton, and vice versa, oscillating around the center of the trap. Results for the effective mass, the Landau critical velocity, and the role of the transverse confinement are also discussed.

  9. Subsonic and Supersonic Effects in Bose-Einstein Condensate

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2003-01-01

    A paper presents a theoretical investigation of subsonic and supersonic effects in a Bose-Einstein condensate (BEC). The BEC is represented by a time-dependent, nonlinear Schroedinger equation that includes terms for an external confining potential term and a weak interatomic repulsive potential proportional to the number density of atoms. From this model are derived Madelung equations, which relate the quantum phase with the number density, and which are used to represent excitations propagating through the BEC. These equations are shown to be analogous to the classical equations of flow of an inviscid, compressible fluid characterized by a speed of sound (g/Po)1/2, where g is the coefficient of the repulsive potential and Po is the unperturbed mass density of the BEC. The equations are used to study the effects of a region of perturbation moving through the BEC. The excitations created by a perturbation moving at subsonic speed are found to be described by a Laplace equation and to propagate at infinite speed. For a supersonically moving perturbation, the excitations are found to be described by a wave equation and to propagate at finite speed inside a Mach cone.

  10. Bose-Einstein condensation of quasi-equilibrium magnons at room temperature under pumping.

    PubMed

    Demokritov, S O; Demidov, V E; Dzyapko, O; Melkov, G A; Serga, A A; Hillebrands, B; Slavin, A N

    2006-09-28

    Bose-Einstein condensation is one of the most fascinating phenomena predicted by quantum mechanics. It involves the formation of a collective quantum state composed of identical particles with integer angular momentum (bosons), if the particle density exceeds a critical value. To achieve Bose-Einstein condensation, one can either decrease the temperature or increase the density of bosons. It has been predicted that a quasi-equilibrium system of bosons could undergo Bose-Einstein condensation even at relatively high temperatures, if the flow rate of energy pumped into the system exceeds a critical value. Here we report the observation of Bose-Einstein condensation in a gas of magnons at room temperature. Magnons are the quanta of magnetic excitations in a magnetically ordered ensemble of magnetic moments. In thermal equilibrium, they can be described by Bose-Einstein statistics with zero chemical potential and a temperature-dependent density. In the experiments presented here, we show that by using a technique of microwave pumping it is possible to excite additional magnons and to create a gas of quasi-equilibrium magnons with a non-zero chemical potential. With increasing pumping intensity, the chemical potential reaches the energy of the lowest magnon state, and a Bose condensate of magnons is formed.

  11. Elements of Vortex-Dipole Dynamics in a Nonuniform Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Sakhel, Roger R.; Sakhel, Asaad R.

    2016-09-01

    The elements of the vortex-dipole (VD) dynamics are numerically examined in a nonuniform Bose-Einstein condensate (BEC) using the time-dependent Gross-Pitaevskii equation that is solved by the split-step Crank-Nicolson method in real time. The BEC is trapped in a harmonic potential, surrounded by a hard-wall box potential, and stirred by an attractive focusing laser. In this regard, we particularly refer to a recent examination by Aioi et al. (Phys. Rev. X, 1: 021003, 2011) who presented controlled VD generation using a red laser in an infinite homogeneous BEC for comparison. It is found that the dynamics in the present nonuniform BEC is quite different from the one reported earlier by Aioi et al. The elements considered are the phase maps that demonstrate the presence of phase rings, the effects of the coupling constant on the vortex lifetime, the density at the vortex core, and the heating effects of the stirrer. Upon a suitable choice of coupling for our system, a VD generated by the moving fragment is transferred to and trapped by the central BEC cloud. The latter serves as a dissipationless vortex respository, where the lifetime of the VD is extended on demand. An analytical model is presented that qualitatively reproduces the wavefunction with its principle features and provides details inaccessible by the present numerical method such as the coupling between stirrer and BEC.

  12. Mixing, demixing, and structure formation in a binary dipolar Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Young-S., Luis E.; Adhikari, S. K.

    2012-12-01

    We study the static properties of disk-shaped binary dipolar Bose-Einstein condensates of 168Er-164Dy and 52Cr-164Dy mixtures under the action of interspecies and intraspecies contact and dipolar interactions and demonstrate the effect of dipolar interaction using the mean-field approach. Throughout this study we use realistic values of interspecis and intraspecies dipolar interactions and the intraspecies scattering lengths and consider the interspecies scattering length as a parameter. The stability of the binary mixture is illustrated through phase plots involving a number of atoms of the species. The binary system always becomes unstable as the number of atoms increases beyond a certain limit. As the interspecies scattering length increases corresponding to more repulsion, an overlapping mixed state of the two species changes to a separated demixed configuration. During the transition from a mixed to a demixed configuration as the interspecies scattering length is increased for parameters near the stability line, the binary condensate shows special transient structures in density in the form of red-blood-cell-like biconcave and Saturn-ring-like shapes, which are direct manifestations of the dipolar interaction.

  13. Tunable Polarons of Slow-Light Polaritons in a Two-Dimensional Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Grusdt, Fabian; Fleischhauer, Michael

    2016-02-01

    When an impurity interacts with a bath of phonons it forms a polaron. For increasing interaction strengths the mass of the polaron increases and it can become self-trapped. For impurity atoms inside an atomic Bose-Einstein condensate (BEC) the nature of this transition is not understood. While Feynman's variational approach to the Fröhlich model predicts a sharp transition for light impurities, renormalization group studies always predict an extended intermediate-coupling region characterized by large phonon correlations. To investigate this intricate regime and to test polaron physics beyond the validity of the Fröhlich model we suggest a versatile experimental setup that allows us to tune both the mass of the impurity and its interactions with the BEC. The impurity is realized as a dark-state polariton (DSP) inside a quasi-two-dimensional BEC. We show that its interactions with the Bogoliubov phonons lead to photonic polarons, described by the Bogoliubov-Fröhlich Hamiltonian, and make theoretical predictions using an extension of a recently introduced renormalization group approach to Fröhlich polarons.

  14. Control of Fano resonances and slow light using Bose-Einstein condensates in a nanocavity

    NASA Astrophysics Data System (ADS)

    Akram, M. Javed; Ghafoor, Fazal; Khan, M. Miskeen; Saif, Farhan

    2017-02-01

    In this study, a standing wave in an optical nanocavity with Bose-Einstein condensate (BEC) constitutes a one-dimensional optical lattice potential in the presence of a finite two bodies atomic interaction. We report that the interaction of a BEC with a standing field in an optical cavity coherently evolves to exhibit Fano resonances in the output field at the probe frequency. The behavior of the reported resonance shows an excellent compatibility with the original formulation of asymmetric resonance as discovered by Fano [U. Fano, Phys. Rev. 124, 1866 (1961), 10.1103/PhysRev.124.1866]. Based on our analytical and numerical results, we find that the Fano resonances and subsequently electromagnetically induced transparency of the probe pulse can be controlled through the intensity of the cavity standing wave field and the strength of the atom-atom interaction in the BEC. In addition, enhancement of the slow light effect by the strength of the atom-atom interaction and its robustness against the condensate fluctuations are realizable using presently available technology.

  15. Study of impurities immersed in a trapped Bose-Einstein condensate*

    NASA Astrophysics Data System (ADS)

    Nho, Kwangsik; Landau, D. P.

    2007-03-01

    Using path integral Monte Carlo simulation methods[1], we have studied properties of impurities immersed in Bose-Einstein Condensates harmonically trapped in low dimemsion. For two-body interactions, we use a hard-sphere potential whose core radius equals its corresponding scattering length. We assume that the impurities experience the external trapping potential. We have tightly confined the motion of trapped particles in one or more direction by increasing the trap anisotropy in order to simulate lower dimensional atomic gases. By varying the strength of the boson-impurity interactions and the number of impurities, we have investigated the effect of impurities on the energetics and structural properties such as the total energy, the density profile, and the superfluid fraction. Our results show that for impurities with larger two-body interactions than the boson-boson interactions, the impurities move away from the trap center and surround the trapped bosons, and the density profile is found to get narrower, with the peak density getting larger. The total superfluid fraction decreases due to the impurities, although the difference becomes smaller and smaller by increasing the trap anisotropy. *Research supported by NASA[1] K. Nho and D. P. Landau, Phys. Rev. A. 72, 023615 (2005).

  16. Dynamic fragmentation in a quenched two-mode Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Wu, Shu-Yuan; Zhong, Hong-Hua; Huang, Jia-Hao; Qin, Xi-Zhou; Lee, Chao-Hong

    2016-06-01

    We investigate the fragmentation in a two-mode Bose-Einstein condensate with Josephson coupling. We explore how the fragmentation and entropy of the ground state depend on the intermode asymmetry and interparticle interactions. Owing to the interplay between the asymmetry and the interactions, a sequence of notches and plateaus in the fragmentation appears with the single-atom tunneling and interaction blockade, respectively. We then analyze the dynamical properties of the fragmentation in three typical quenches of the asymmetry: linear, sudden, and periodic quenches. In a linear quench, the final state is a fragmented state due to the sequential Landau-Zener tunneling, which can be analytically explained by applying the two-level Landau-Zener formula for each avoided level crossing. In a sudden quench, the fragmentation exhibits persistent fluctuations that sensitively depend on the interparticle interactions and intermode coupling. In a periodic quench, the fragmentation is modulated by the periodic driving, and a suitable modulation may allow one to control the fragmentation.

  17. Vortex reconnections and rebounds in trapped atomic Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Galantucci, Luca; Serafini, Simone; Iseni, Elena; Bienaime', Tom; Bisset, Russell; Dalfovo, Franco; Lamporesi, Giacomo; Ferrari, Gabriele; Barenghi, Carlo F.

    2016-11-01

    Reconnections and interactions of filamentary coherent structures play a fundamental role in the dynamics of classical and quantum fluids, plasmas and nematic liquid crystals. In quantum fluids vorticity is concentrated into discrete (quantised) vortex lines (unlike ordinary fluids where vorticity is a continuous field), turning vortex reconnections into isolated events, conceptually easier to study. In order to investigate the impact of non-homogeneous density fields on the dynamics of quantum reconnections, we perform a numerical study of two-vortex interactions in magnetically trapped elongated Bose-Einstein condensates in the T=0 limit. We observe different vortex interactions regimes depending on the vortex orientations and their relative velocity: unperturbed orbiting, bounce dynamics, single and double reconnection events. The key ingredients driving the dynamics are the anti-parallel preferred alignment of the vortices and the impact of density gradients arising from the inhomogeneity of the trapping potential. The results are confirmed by ongoing experiments in Trento performed employing an innovative non-destrutive real-time imaging technique capable of determining the axial dynamics and the orientation of the vortices.

  18. Collective dynamics of a spin-orbit-coupled Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Hu, Fang-Qi; Wang, Jian-Jun; Yu, Zi-Fa; Zhang, Ai-Xia; Xue, Ju-Kui

    2016-02-01

    We study the collective dynamics of the spin-orbit coupled two pseudospin components of a Bose-Einstein condensate trapped in a quasi-one-dimensional harmonic potential, by using variational and directly numerical approach of binary mean-field Gross-Pitaevskii equations. The results show that, because of strong coupling of spin-orbit coupling (SOC), Rabi coupling, and atomic interaction, the collective dynamics of the system behave as complex characters. When the Rabi coupling is absent, the density profiles of the system preserve the Gauss type and the wave packets do harmonic oscillations. The amplitude of the collective oscillations increases with SOC. Furthermore, when the SOC strength increases, the dipole oscillations of the two pseudospin components undergo a transition from in-phase to out-of-phase oscillations. When the Rabi coupling present, there will exist a critical value of SOC strength (which depends on the Rabi coupling and atomic interaction). If the SOC strength is less than this critical value, the density profiles of the system can preserve the Gauss type and the wave packets do anharmonic (the frequency of dipole oscillations depends on SOC) oscillations synchronously (i.e., in-phase oscillations). However, if the SOC strength is larger than this critical value, the wave packets are dynamically fragmented and the stable dipole oscillations of the system can not exist. The collective dynamics of the system can be controlled by adjusting the atomic interaction, SOC, and Rabi-coupling strength.

  19. Collective dynamics of a spin-orbit-coupled Bose-Einstein condensate.

    PubMed

    Hu, Fang-Qi; Wang, Jian-Jun; Yu, Zi-Fa; Zhang, Ai-Xia; Xue, Ju-Kui

    2016-02-01

    We study the collective dynamics of the spin-orbit coupled two pseudospin components of a Bose-Einstein condensate trapped in a quasi-one-dimensional harmonic potential, by using variational and directly numerical approach of binary mean-field Gross-Pitaevskii equations. The results show that, because of strong coupling of spin-orbit coupling (SOC), Rabi coupling, and atomic interaction, the collective dynamics of the system behave as complex characters. When the Rabi coupling is absent, the density profiles of the system preserve the Gauss type and the wave packets do harmonic oscillations. The amplitude of the collective oscillations increases with SOC. Furthermore, when the SOC strength increases, the dipole oscillations of the two pseudospin components undergo a transition from in-phase to out-of-phase oscillations. When the Rabi coupling present, there will exist a critical value of SOC strength (which depends on the Rabi coupling and atomic interaction). If the SOC strength is less than this critical value, the density profiles of the system can preserve the Gauss type and the wave packets do anharmonic (the frequency of dipole oscillations depends on SOC) oscillations synchronously (i.e., in-phase oscillations). However, if the SOC strength is larger than this critical value, the wave packets are dynamically fragmented and the stable dipole oscillations of the system can not exist. The collective dynamics of the system can be controlled by adjusting the atomic interaction, SOC, and Rabi-coupling strength.

  20. Nonautonomous matter waves in a spin-1 Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Shen, Yu-Jia; Gao, Yi-Tian; Zuo, Da-Wei; Sun, Yu-Hao; Feng, Yu-Jie; Xue, Long

    2014-06-01

    To investigate nonautonomous matter waves with time-dependent modulation in a one-dimensional trapped spin-1 Bose-Einstein condensate, we hereby work on the generalized three-coupled Gross-Pitaevskii equations by means of the Hirota bilinear method. By modulating the external trap potential, atom gain or loss, and coupling coefficients, we can obtain several nonautonomous matter-wave solitons and rogue waves including "bright" and "dark" shapes and arrive at the following conclusions: (i) the external trap potential and atom gain or loss can influence the propagation of matter-wave solitons and the duration and frequency of bound solitonic interaction, but they have little effect on the head-on solitonic interaction; (ii) through numerical simulation, stable evolution of the matter-wave solitons is realized with a perturbation of 5% initial random noise, and the spin-exchange interaction of atoms can be affected by the time-dependent modulation; (iii) under the influence of a periodically modulated trap potential and periodic atom gain or loss, rogue waves can emerge in the superposition of localized character and periodic oscillating properties.

  1. Nonautonomous matter waves in a spin-1 Bose-Einstein condensate.

    PubMed

    Shen, Yu-Jia; Gao, Yi-Tian; Zuo, Da-Wei; Sun, Yu-Hao; Feng, Yu-Jie; Xue, Long

    2014-06-01

    To investigate nonautonomous matter waves with time-dependent modulation in a one-dimensional trapped spin-1 Bose-Einstein condensate, we hereby work on the generalized three-coupled Gross-Pitaevskii equations by means of the Hirota bilinear method. By modulating the external trap potential, atom gain or loss, and coupling coefficients, we can obtain several nonautonomous matter-wave solitons and rogue waves including "bright" and "dark" shapes and arrive at the following conclusions: (i) the external trap potential and atom gain or loss can influence the propagation of matter-wave solitons and the duration and frequency of bound solitonic interaction, but they have little effect on the head-on solitonic interaction; (ii) through numerical simulation, stable evolution of the matter-wave solitons is realized with a perturbation of 5% initial random noise, and the spin-exchange interaction of atoms can be affected by the time-dependent modulation; (iii) under the influence of a periodically modulated trap potential and periodic atom gain or loss, rogue waves can emerge in the superposition of localized character and periodic oscillating properties.

  2. Bose-Einstein condensates with balanced gain and loss beyond mean-field theory

    NASA Astrophysics Data System (ADS)

    Dast, Dennis; Haag, Daniel; Cartarius, Holger; Main, Jörg; Wunner, Günter

    2016-11-01

    Most of the work done in the field of Bose-Einstein condensates with balanced gain and loss has been performed in the mean-field approximation using the P T -symmetric Gross-Pitaevskii equation. In this work we study the many-particle dynamics of a two-mode condensate with balanced gain and loss described by a master equation in Lindblad form whose purity periodically drops to small values but then is nearly completely restored. This effect cannot be covered by the mean-field approximation, in which a completely pure condensate is assumed. We present analytic solutions for the dynamics in the noninteracting limit and use the Bogoliubov backreaction method to discuss the influence of the on-site interaction. Our main result is that the strength of the purity revivals is almost exclusively determined by the strength of the gain and loss and is independent of the amount of particles in the system and the interaction strength. For larger particle numbers, however, strong revivals are shifted towards longer times, but by increasing the interaction strength these strong revivals again occur earlier.

  3. Tunneling dynamics and band structures of three weakly coupled Bose-Einstein condensates.

    PubMed

    Guo, Qiuyi; Chen, XuZong; Wu, Biao

    2014-08-11

    We study the tunneling dynamics and energy bands of three Bose-Einstein condensates which are coupled weakly with each other. The study is carried out with both the mean-filed model and the second-quantized model. The results from these two models are compared and found to agree with each other when the particle number is large. Without interaction, this system possesses a Dirac point in its energy band. This Dirac point is immediately destroyed and develops into a loop structure with arbitrary small interaction. This loop structure has a strong effect on the tunneling dynamics. We find that the tunneling dynamics in this system is very sensitive to the system parameter, e.g., the interaction strength. This sensitivity is found to be caused by the chaos in the mean-field model and the avoided energy crossings with tiny gaps in the second-quantized model. This result gives a certain indication on how the classical dynamics and quantum dynamics are connected in the semi-classical limit. Our mean-field results are also valid for three mutually coupled optical nonlinear waveguides.

  4. Energy Band and Josephson Dynamics of Spin-Orbit Coupled Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Yu, Zi-Fa; Xue, Ju-Kui

    2015-10-01

    We theoretically investigate the energy band structure and Josephson dynamics of a spin-orbit coupled Bose-Einstein condensate in a double-well potential. We study the energy band structure and the corresponding tunneling dynamics of the system by properly adjusting the SO coupling, Raman coupling, Zeeman field and atomic interactions. The coupled effects of SO coupling, Raman coupling, Zeeman field and atomic interactions lead to the appearance of complex energy band structure including the loop structure. Particularly, the emergence of the loop structure in energy band also depends on SO coupling, Raman coupling, Zeeman field and atomic interactions. Correspondingly, the Josephson dynamics of the system are strongly related to the energy band structure. Especially, the emergence of the loop structure results in complex tunneling dynamics, including suppression-revival transitions and self-trapping of atoms transfer between two spin states and two wells. This engineering provides a possible means for studying energy level and corresponding dynamics of two-species SO coupled BECs. Supported by the National Natural Science Foundation of China under Grant Nos. 11274255 and 11305132, by Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20136203110001, by the Natural Science Foundation of Gansu province under Grant No. 2011GS04358, and by Creation of Science and Technology of Northwest Normal University under Grant Nos. NWNU-KJCXGC-03-48, NWNU-LKQN-12-12

  5. Homogeneous one-dimensional Bose-Einstein condensate in the Bogoliubov’s regime

    NASA Astrophysics Data System (ADS)

    Castellanos, Elías

    2016-08-01

    We analyze the corrections caused by finite size effects upon the ground state properties of a homogeneous one-dimensional (1D) Bose-Einstein condensate. We assume from the very beginning that the Bogoliubov’s formalism is valid and consequently, we show that in order to obtain a well-defined ground state properties, finite size effects of the system must be taken into account. Indeed, the formalism described in the present paper allows to recover the usual properties related to the ground state of a homogeneous 1D Bose-Einstein condensate but corrected by finite size effects of the system. Finally, this scenario allows us to analyze the sensitivity of the system when the Bogoliubov’s regime is valid and when finite size effects are present. These facts open the possibility to apply these ideas to more realistic scenarios, e.g. low-dimensional trapped Bose-Einstein condensates.

  6. Thermalization and Bose-Einstein condensation of quantum light in bulk nonlinear media

    NASA Astrophysics Data System (ADS)

    Chiocchetta, A.; Larré, P.-É.; Carusotto, I.

    2016-07-01

    We study the thermalization and the Bose-Einstein condensation of a paraxial, spectrally narrow beam of quantum light propagating in a lossless bulk Kerr medium. The spatiotemporal evolution of the quantum optical field is ruled by a Heisenberg equation analogous to the quantum nonlinear Schrödinger equation of dilute atomic Bose gases. Correspondingly, in the weak-nonlinearity regime, the phase-space density evolves according to the Boltzmann equation. Expressions for the thermalization time and for the temperature and the chemical potential of the eventual Bose-Einstein distribution are found. After discussing experimental issues, we introduce an optical setup allowing the evaporative cooling of a guided beam of light towards Bose-Einstein condensation. This might serve as a novel source of coherent light.

  7. Parametric resonance of capillary waves at the interface between two immiscible Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Kobyakov, D.; Bychkov, V.; Lundh, E.; Bezett, A.; Marklund, M.

    2012-08-01

    We study the parametric resonance of capillary waves on the interface between two immiscible Bose-Einstein condensates pushed towards each other by an oscillating force. Guided by analytical models, we solve numerically the coupled Gross-Pitaevskii equations for a two-component Bose-Einstein condensate at zero temperature. We show that, at moderate amplitudes of the driving force, the instability is stabilized due to nonlinear modifications of the oscillation frequency. When the amplitude of the driving force is large enough, we observe a detachment of droplets from the Bose-Einstein condensates, resulting in the generation of quantum vortices (skyrmions). We analytically investigate the vortex dynamics, and conditions of quantized vortex generation.

  8. Cosmological perturbations during the Bose-Einstein condensation of dark matter

    SciTech Connect

    Freitas, R.C.; Gonçalves, S.V.B. E-mail: sergio.vitorino@pq.cnpq.br

    2013-04-01

    In the present work, we analyze the evolution of the scalar and tensorial perturbations and the quantities relevant for the physical description of the Universe, as the density contrast of the scalar perturbations and the gravitational waves energy density during the Bose-Einstein condensation of dark matter. The behavior of these parameters during the Bose-Einstein phase transition of dark matter is analyzed in details. To study the cosmological dynamics and evolution of scalar and tensorial perturbations in a Universe with and without cosmological constant we use both analytical and numerical methods. The Bose-Einstein phase transition modifies the evolution of gravitational waves of cosmological origin, as well as the process of large-scale structure formation.

  9. Spin-orbit-coupled Bose-Einstein condensates in a circular box

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Zhu; Xie, Mi

    2015-05-01

    In this paper we discuss the properties of the ground state of a Rashba spin-orbit (SO) coupled Bose-Einstein condensate (BEC) in a circular box with hard walls, especially the influence of the SO coupling. We first give the analytical solutions for non-interacting particles with Rashba coupling in a circular box. The solution shows that the eigenstate has a Skyrmion-type spin texture, but the Skyrmion charge is usually not an integer, which is different from the case of a harmonic trap. Then, we consider the ground state of a SO-coupled BEC with weak interparticle interaction by numerically solving the Gross-Pitaevskii (GP) equation. We show that a quantum phase transition will appear as the SO coupling strength increases and give the phase diagram. Various aspects of the BEC ground state are discussed, especially their changes before and after the phase transition, such as the energy, the particle distribution, and the spin distribution. When the SO coupling is very strong or the box is very large, the trapped system should be similar to that in free space. We also discuss the relation between the ground states in the box and in free space.

  10. Three-mode resonant coupling of collective excitations in a Bose-Einstein condensate

    SciTech Connect

    Ma Yongli; Huang, Guoxiang; Hu Bambi

    2005-04-01

    We make a systematic study of the resonant mode coupling of the collective excitations at zero temperature in a Bose-Einstein condensate (BEC). (i) Based on the Gross-Pitaevskii equation we derive a set of nonlinearly coupled envelope equations for a three-mode resonant interaction (TMRI) by means of a method of multiple scales. (ii) We calculate the coupling matrix elements for the TMRI and show that the divergence appearing in previous studies can be eliminated completely by using a Fetter-like variational approximation for the ground-state wave function of the condensate. (iii) We provide the selection rules in mode-mode interaction processes [including TMRI and second-harmonic generation (SHG)] according to the symmetry of the excitations. (iv) By solving the nonlinearly coupled envelope equations we obtain divergence-free nonlinear amplitudes for the TMRI and SHG processes and show that our theoretical results on the shape oscillations of the condensate agree well with the experimental ones. We suggest also an experiment to check the theoretical prediction of the present study on the TMRI of collective excitations in a BEC.

  11. Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps

    PubMed Central

    Zhang, Xiao-Fei; Han, Wei; Wen, Lin; Zhang, Peng; Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang

    2015-01-01

    Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures. PMID:25731962

  12. Tunable Spin-orbit Coupling and Quantum Phase Transition in a Trapped Bose-Einstein Condensate

    PubMed Central

    Zhang, Yongping; Chen, Gang; Zhang, Chuanwei

    2013-01-01

    Spin-orbit coupling (SOC), the intrinsic interaction between a particle spin and its motion, is responsible for various important phenomena, ranging from atomic fine structure to topological condensed matter physics. The recent experimental breakthrough on the realization of SOC for ultra-cold atoms provides a completely new platform for exploring spin-orbit coupled superfluid physics. However, the SOC strength in the experiment is not tunable. In this report, we propose a scheme for tuning the SOC strength through a fast and coherent modulation of the laser intensities. We show that the many-body interaction between atoms, together with the tunable SOC, can drive a quantum phase transition (QPT) from spin-balanced to spin-polarized ground states in a harmonic trapped Bose-Einstein condensate (BEC), which resembles the long-sought Dicke QPT. We characterize the QPT using the periods of collective oscillations of the BEC, which show pronounced peaks and damping around the quantum critical point. PMID:23727689

  13. Nonlinear polarization waves in a two-component Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Kamchatnov, A. M.; Kartashov, Y. V.; Larré, P.-É.; Pavloff, N.

    2014-03-01

    A two-component Bose-Einstein condensate whose dynamics is described by a system of coupled Gross-Pitaevskii equations accommodates waves with different symmetries. A first type of waves corresponds to excitations for which the motion of both components is locally in phase. For the second type of waves, the two components have a counterphase local motion. When the values of the inter- and intracomponent interaction constants are different, the long-wavelength behavior of these two modes corresponds to two types of sound with different velocities. In the limit of weak nonlinearity and small dispersion, the first mode is described by the well-known Korteweg-de Vries equation. In the same limit, we show that the second mode can be described by the Gardner equation if the values of the two intracomponent interaction constants are sufficiently close. This leads to a rich variety of nonlinear excitations (solitons, kinks, algebraic solitons, breathers) which do not exist in the Korteweg-de Vries description.

  14. Depairing and Bose-Einstein-condensation temperatures in a simple boson-fermion model of superconductors

    NASA Astrophysics Data System (ADS)

    Mamedov, T. A.; de Llano, M.

    2007-03-01

    Starting from the Friedberg-TD Lee Hamiltonian describing a coexisting and dynamically interacting many-particle binary boson-fermion gas mixture with a coupling (λ) -dependent gap 2Δ(λ) in the boson dispersion relation for the s -wave Cooper or BCS model interaction, we deduce several observed characteristic features of high-temperature superconductors at the simplest level. Analytic expressions for both the unpaired-fermion and boson number densities, as well for the fermion chemical potential μ(λ,T) , all of which vary with the degree of bosonization and with temperature T , are derived in detail using two-time, finite-temperature Green function techniques. Simple implicit formulas are then obtained for both two and three dimensions for the pseudogap T* and Bose-Einstein condensation Tc temperatures in terms of μ(λ,T) and 2Δ(λ) . In particular, even at the s -wave level we find a self-consistent description of the generic phase diagram observed in cuprates, including the appearance of a pseudogap and a dome-shaped Tc vs doping behavior both of which hinge on the gapped boson spectrum.

  15. Exotic vortex lattices in a rotating binary dipolar Bose-Einstein condensate.

    PubMed

    Zhang, Xiao-Fei; Wen, Lin; Dai, Cai-Qing; Dong, Rui-Fang; Jiang, Hai-Feng; Chang, Hong; Zhang, Shou-Gang

    2016-01-18

    In the last decade, considerable advances have been made in the investigation of dipolar quantum gases. Previous theoretical investigations of a rotating binary dipolar Bose-Einstein condensate, where only one component possesses dipole moment, were mainly focused on two special orientations of the dipoles: perpendicular or parallel to the plane of motion. Here we study the ground-state and rotational properties of such a system for an arbitrary orientation of the dipoles. We demonstrate the ground-state vortex structures depend strongly on the relative strength between dipolar and contact interactions and the rotation frequency, as well as on the orientation of the dipoles. In the absence of rotation, the tunable dipolar interaction can be used to induce the squeezing or expansion of the cloud, and to derive the phase transition between phase coexistence and separation. Under finite rotation, the system is found to exhibit exotic ground-state vortex configurations, such as kernel-shell, vortex necklace, and compensating stripe vortex structures. We also check the validity of the Feynman relation, and find no significant deviations from it. The obtained results open up alternate ways for the quantum control of dipolar quantum gases.

  16. Creating full-Bloch Bose-Einstein condensates with Raman q-plates

    NASA Astrophysics Data System (ADS)

    Schultz, Justin T.; Hansen, Azure; Murphree, Joseph D.; Jayaseelan, Maitreyi; Bigelow, Nicholas P.

    2016-06-01

    A coherent two-photon optical Raman interaction in a pseudo-spin-1/2 Bose-Einstein condensate (BEC) serves as a q-plate for atoms, converting spin to orbital angular momentum. This Raman q-plate has a singular pattern in its polarization distribution in analogy to the singular birefringent q-plates used in singular optics. The vortex winding direction and magnitude as well as the final spin state of the BEC depend on the initial spin state and the topology of the optical Raman q-plate beams. Drawing on the mathematical and geometric foundations of singular optics, we derive the equivalent Jones matrix for this Raman q-plate and use it to create and characterize atomic spin singularities in the BEC that are analogous to optical C-point singularities in polarization. By tuning the optical Raman parameters, we can generate a coreless vortex spin texture which contains every possible superposition in a two-state system. We identify this spin texture as a full-Bloch BEC since every point on the Bloch sphere is represented at some point in the cross section of the atomic cloud. This spin-orbit interaction and the spin textures it generates may allow for the observation of interesting geometric phases in matter waves and lead to schemes for topological quantum computation with spinor BECs.

  17. Integrability of the hyperbolic reduced Maxwell-Bloch equations for strongly correlated Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Arnaudon, Alexis; Gibbon, John D.

    2017-07-01

    We derive and study the hyperbolic reduced Maxwell-Bloch (HRMB) equations, a simplified model for the dynamics of strongly correlated Bose-Einstein condensates (BECs), and in particular for the interaction between the BEC atoms and its evaporated atoms under the strong interactions. This equation is one among four, which are proven to be integrable via the existence of a Lax pair, and thus the method of inverse scattering transform. Another equation is the reduced Maxwell-Bloch equation of quantum optics and the two others do not have physical applications yet. By studying the linear stability of the constant solutions of these four equations we observe various regimes, from stable, to modulational unstable, and unstable at all frequencies. The finite-dimensional reduction of the RMB equations is also used to give more insight into the constant solutions of these equations. From this study, we find that the HRMB equation arising from strongly correlated BECs is stable under the particular condition that the transition rate of evaporation is not too large compared to the number of evaporated atoms. We then derive explicit soliton solutions of the RMB equations and use numerical simulations to show collisions of solitons and kink solitons.

  18. Scattering of a vortex pair by a single quantum vortex in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Smirnov, L. A.; Smirnov, A. I.; Mironov, V. A.

    2016-01-01

    We analyze the scattering of vortex pairs (the particular case of 2D dark solitons) by a single quantum vortex in a Bose-Einstein condensate with repulsive interaction between atoms. For this purpose, an asymptotic theory describing the dynamics of such 2D soliton-like formations in an arbitrary smoothly nonuniform flow of a ultracold Bose gas is developed. Disregarding the radiation loss associated with acoustic wave emission, we demonstrate that vortex-antivortex pairs can be put in correspondence with quasiparticles, and their behavior can be described by canonical Hamilton equations. For these equations, we determine the integrals of motion that can be used to classify various regimes of scattering of vortex pairs by a single quantum vortex. Theoretical constructions are confirmed by numerical calculations performed directly in terms of the Gross-Pitaevskii equation. We propose a method for estimating the radiation loss in a collision of a soliton-like formation with a phase singularity. It is shown by direct numerical simulation that under certain conditions, the interaction of vortex pairs with a core of a single quantum vortex is accompanied by quite intense acoustic wave emission; as a result, the conditions for applicability of the asymptotic theory developed here are violated. In particular, it is visually demonstrated by a specific example how radiation losses lead to a transformation of a vortex-antivortex pair into a vortex-free 2D dark soliton (i.e., to the annihilation of phase singularities).

  19. Exotic vortex lattices in a rotating binary dipolar Bose-Einstein condensate

    PubMed Central

    Zhang, Xiao-Fei; Wen, Lin; Dai, Cai-Qing; Dong, Rui-Fang; Jiang, Hai-Feng; Chang, Hong; Zhang, Shou-Gang

    2016-01-01

    In the last decade, considerable advances have been made in the investigation of dipolar quantum gases. Previous theoretical investigations of a rotating binary dipolar Bose-Einstein condensate, where only one component possesses dipole moment, were mainly focused on two special orientations of the dipoles: perpendicular or parallel to the plane of motion. Here we study the ground-state and rotational properties of such a system for an arbitrary orientation of the dipoles. We demonstrate the ground-state vortex structures depend strongly on the relative strength between dipolar and contact interactions and the rotation frequency, as well as on the orientation of the dipoles. In the absence of rotation, the tunable dipolar interaction can be used to induce the squeezing or expansion of the cloud, and to derive the phase transition between phase coexistence and separation. Under finite rotation, the system is found to exhibit exotic ground-state vortex configurations, such as kernel-shell, vortex necklace, and compensating stripe vortex structures. We also check the validity of the Feynman relation, and find no significant deviations from it. The obtained results open up alternate ways for the quantum control of dipolar quantum gases. PMID:26778736

  20. Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps.

    PubMed

    Zhang, Xiao-Fei; Han, Wei; Wen, Lin; Zhang, Peng; Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang

    2015-03-03

    Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures.