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Sample records for bose-einstein condensed magnetoexcitons

  1. 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.

  2. 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…

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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).

  13. 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.

  14. 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).

  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. 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).

  17. 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.

  18. 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.

  19. 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).

  20. 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.

  1. 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.

  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. 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?

  4. 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.

  5. 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.

  6. 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.}

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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}

  16. 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.

  17. 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.

  18. 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].

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. 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.

  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. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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).

  7. 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.

  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. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  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. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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).

  3. 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}.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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.

  16. Properties of spin-orbit-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Zhang, Yongping; Mossman, Maren Elizabeth; Busch, Thomas; Engels, Peter; Zhang, Chuanwei

    2016-06-01

    The experimental and theoretical research of spin-orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work, has helped to lay the foundation, or has developed new and relevant techniques. After examining the experimental accessibility of all relevant spin-orbit coupling parameters, we discuss the fundamental properties and general applications of spin-orbit-coupled Bose-Einstein condensates (BECs) over a wide range of physical situations. For the harmonically trapped case, we show that the ground state phase transition is a Dicke-type process and that spin-orbit-coupled BECs provide a unique platform to simulate and study the Dicke model and Dicke phase transitions. For a homogeneous BEC, we discuss the collective excitations, which have been observed experimentally using Bragg spectroscopy. They feature a roton-like minimum, the softening of which provides a potential mechanism to understand the ground state phase transition. On the other hand, if the collective dynamics are excited by a sudden quenching of the spin-orbit coupling parameters, we show that the resulting collective dynamics can be related to the famous Zitterbewegung in the relativistic realm. Finally, we discuss the case of a BEC loaded into a periodic optical potential. Here, the spin-orbit coupling generates isolated flat bands within the lowest Bloch bands whereas the nonlinearity of the system leads to dynamical instabilities of these Bloch waves. The experimental verification of this instability illustrates the lack of Galilean invariance in the system.

  17. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Bose-Einstein condensates form in heuristics learned by ciliates deciding to signal 'social' commitments.

    PubMed

    Clark, Kevin B

    2010-03-01

    Fringe quantum biology theories often adopt the concept of Bose-Einstein condensation when explaining how consciousness, emotion, perception, learning, and reasoning emerge from operations of intact animal nervous systems and other computational media. However, controversial empirical evidence and mathematical formalism concerning decoherence rates of bioprocesses keep these frameworks from satisfactorily accounting for the physical nature of cognitive-like events. This study, inspired by the discovery that preferential attachment rules computed by complex technological networks obey Bose-Einstein statistics, is the first rigorous attempt to examine whether analogues of Bose-Einstein condensation precipitate learned decision making in live biological systems as bioenergetics optimization predicts. By exploiting the ciliate Spirostomum ambiguum's capacity to learn and store behavioral strategies advertising mating availability into heuristics of topologically invariant computational networks, three distinct phases of strategy use were found to map onto statistical distributions described by Bose-Einstein, Fermi-Dirac, and classical Maxwell-Boltzmann behavior. Ciliates that sensitized or habituated signaling patterns to emit brief periods of either deceptive 'harder-to-get' or altruistic 'easier-to-get' serial escape reactions began testing condensed on initially perceived fittest 'courting' solutions. When these ciliates switched from their first strategy choices, Bose-Einstein condensation of strategy use abruptly dissipated into a Maxwell-Boltzmann computational phase no longer dominated by a single fittest strategy. Recursive trial-and-error strategy searches annealed strategy use back into a condensed phase consistent with performance optimization. 'Social' decisions performed by ciliates showing no nonassociative learning were largely governed by Fermi-Dirac statistics, resulting in degenerate distributions of strategy choices. These findings corroborate

  4. Bose-Einstein condensates in strong electric fields: Effective gauge potentials and rotating states

    SciTech Connect

    Kailasvuori, J.M.; Hansson, T.H.; Kavoulakis, G.M.

    2002-11-01

    Magnetically trapped atoms in Bose-Einstein condensates are spin polarized. Since the magnetic field is inhomogeneous, the atoms acquire Berry phases of the Aharonov-Bohm type during adiabatic motion. In the presence of an electric field, there is an additional Aharonov-Casher effect. Taking into account the limitations on the strength of the electric fields due to the polarizability of the atoms, we investigate the extent to which these effects can be used to induce rotation in a Bose-Einstein condensate.

  5. Control of a Bose-Einstein condensate by dissipation: Nonlinear Zeno effect

    SciTech Connect

    Shchesnovich, V. S.; Konotop, V. V.

    2010-05-15

    We show that controlled dissipation can be used as a tool for exploring fundamental phenomena and managing mesoscopic systems of cold atoms and Bose-Einstein condensates. Even the simplest boson-Josephson junction, that is, a Bose-Einstein condensate in a double-well trap, subjected to removal of atoms from one of the two potential minima allows one to observe such phenomena as the suppression of losses and the nonlinear Zeno effect. In such a system the controlled dissipation can be used to create desired macroscopic states and implement controlled switching among different quantum regimes.

  6. 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.

  7. A spectral collocation method for a rotating Bose-Einstein condensation in optical lattices

    NASA Astrophysics Data System (ADS)

    Li, Z.-C.; Chen, S.-Y.; Chien, C.-S.; Chen, H.-S.

    2011-06-01

    We extend the study of spectral collocation methods (SCM) in Li et al. (2009) [1] for semilinear elliptic eigenvalue problems to that for a rotating Bose-Einstein condensation (BEC) and a rotating BEC in optical lattices. We apply the Lagrange interpolants using the Legendre-Gauss-Lobatto points to derive error bounds for the SCM. The optimal error bounds are derived for both H-norm and L-norm. Extensive numerical experiments on a rotating Bose-Einstein condensation and a rotating BEC in optical lattices are reported. Our numerical results show that the convergence rate of the SCM is exponential, and is independent of the collocation points we choose.

  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. 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

  11. 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.

  12. Effective-mass analysis of Bose-Einstein condensates in optical lattices: Stabilization and levitation

    SciTech Connect

    Pu, H.; Zhang, W.; Meystre, P.; Baksmaty, L.O.; Bigelow, N.P.

    2003-04-01

    We investigate the time evolution of a Bose-Einstein condensate in a periodic optical potential. Using an effective mass formalism, we study the equation of motion for the envelope function modulating the Bloch states of the lattice potential. In particular, we show how the negative effective-mass affects the dynamics of the condensate.

  13. 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

  14. On the occurrence and detectability of Bose-Einstein condensation in helium white dwarfs

    SciTech Connect

    Benvenuto, O.G.; Vito, M.A. De E-mail: adevito@fcaglp.unlp.edu.ar

    2011-02-01

    It has been recently proposed that helium white dwarfs may provide promising conditions for the occurrence of the Bose-Einstein condensation. The argument supporting this expectation is that in some conditions attained in the core of these objects, the typical De Broglie wavelength associated with helium nuclei is of the order of the mean distance between neighboring nuclei. In these conditions the system should depart from classical behavior showing quantum effects. As helium nuclei are bosons, they are expected to condense. In order to explore the possibility of detecting the Bose-Einstein condensation in the evolution of helium white dwarfs we have computed a set of models for a variety of stellar masses and values of the condensation temperature. We do not perform a detailed treatment of the condensation process but mimic it by suppressing the nuclei contribution to the equation of state by applying an adequate function. As the cooling of white dwarfs depends on average properties of the whole stellar interior, this procedure should be suitable for exploring the departure of the cooling process from that predicted by the standard treatment. We find that the Bose-Einstein condensation has noticeable, but not dramatic effects on the cooling process only for the most massive white dwarfs compatible with a helium dominated interior ( ≈ 0.50M{sub s}un) and very low luminosities (say, Log(L/L{sub s}un) < −4.0). These facts lead us to conclude that it seems extremely difficult to find observable signals of the Bose-Einstein condensation. Recently, it has been suggested that the population of helium white dwarfs detected in the globular cluster NGC 6397 is a good candidate for detecting signals of the Bose-Einstein condensation. We find that these stars have masses too low and are too bright to have an already condensed interior.

  15. 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.

  16. Bogoliubov space of a Bose-Einstein condensate and quantum spacetime fluctuations

    SciTech Connect

    Rivas, J. I.; Camacho, A.; Goeklue, E.

    2012-08-24

    We analyze the role that metric fluctuations could have on the features of a Bose-Einstein condensate. Particularly, the Bogoliubov space associated to it is considered and it will be shown that the pressure and the speed of sound of the ground state define an expression allowing us to determine the average size of these fluctuations.

  17. Zero-Temperature, Mean-Field Theory of Atomic Bose-Einstein Condensates

    PubMed Central

    Edwards, Mark; Dodd, R. J.; Clark, Charles W.; Burnett, K.

    1996-01-01

    We review the application of zero-temperature, mean-field theory to current experimental atomic Bose-Einstein condensates. We assess the validity of the approximations made by comparing the mean-field results with a variety of experimental data. PMID:27805108

  18. 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.

  19. Low-acceleration instability of a Bose-Einstein condensate in an optical lattice.

    PubMed

    Zheng, Yi; Kostrun, Marijan; Javanainen, Juha

    2004-12-03

    We study a Bose-Einstein condensate in a one-dimensional accelerated optical lattice using the mean-field version of the Bose-Hubbard model. Reminiscent of recent experiments [M. Cristiani et al., Opt. Express 12, 4 (2004)], we find a new type of an instability in this system that occurs in the limit when the acceleration is small.

  20. The Evolution of Hyperedge Cardinalities and Bose-Einstein Condensation in Hypernetworks

    PubMed Central

    Guo, Jin-Li; Suo, Qi; Shen, Ai-Zhong; Forrest, Jeffrey

    2016-01-01

    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. PMID:27669903

  1. Optical analog of the Iordanskii force in a Bose-Einstein condensate

    SciTech Connect

    Leonhardt, U.; Oehberg, P.

    2003-05-01

    A vortex in a Bose-Einstein condensate generates the optical analog of the Aharonov-Bohm effect when illuminated with slow light. In contrast to the original Aharonov-Bohm effect the vortex will exchange forces with the light that leads to a measurable motion of the vortex.

  2. Comment on 'Feshbach resonance and growth of a Bose-Einstein condensate'

    SciTech Connect

    Wu, Lei; Jiang, Ren-Jie; Pei, Yu-hua; Zhang, Jie-Fang

    2007-03-15

    Our analytical solution shows that the number of atoms continuously injected into Bose-Einstein condensate from the reservoir depends on the linear gain/loss coefficient, and cannot be controlled by applying the external magnetic field via Feshbach resonance reported by Yuce and Kilic [Phys. Rev. A 74, 033609 (2006)].

  3. Excess Noise Depletion of a Bose-Einstein Condensate in an Optical Cavity

    NASA Astrophysics Data System (ADS)

    Szirmai, G.; Nagy, D.; Domokos, P.

    2009-02-01

    Quantum fluctuations of a cavity field coupled into the motion of ultracold bosons can be strongly amplified by a mechanism analogous to the Petermann excess noise factor in lasers with unstable cavities. For a Bose-Einstein condensate in a stable optical resonator, the excess noise effect amounts to a significant depletion on long time scales.

  4. 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.

  5. 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.

  6. Ramsey fringes in a Bose-Einstein condensate between atoms and molecules.

    PubMed

    Kokkelmans, S J J M F; Holland, M J

    2002-10-28

    In a recent experiment, a Feshbach scattering resonance was exploited to observe Ramsey fringes in a 85Rb Bose-Einstein condensate. The oscillation frequency corresponded to the binding energy of the molecular state. We show that the observations are remarkably consistent with predictions of a resonance field theory in which the fringes arise from oscillations between atoms and molecules.

  7. Landau-Zener tunneling of Bose-Einstein condensates in an optical lattice

    SciTech Connect

    Konotop, V.V.; Kevrekidis, P.G.; Salerno, M.

    2005-08-15

    A theory of the nonsymmetric Landau-Zener tunneling of Bose-Einstein condensates in deep optical lattices is presented. It is shown that periodic exchange of matter between the bands is described by a set of linearly coupled nonlinear Schroedinger equations. The key role of the modulational instability in rendering the interband transitions irreversible is highlighted.

  8. 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.

  9. Tachyon condensation due to domain-wall annihilation in Bose-Einstein condensates.

    PubMed

    Takeuchi, Hiromitsu; Kasamatsu, Kenichi; Tsubota, Makoto; Nitta, Muneto

    2012-12-14

    We show theoretically that a domain-wall annihilation in two-component Bose-Einstein condensates causes tachyon condensation accompanied by spontaneous symmetry breaking in a two-dimensional subspace. Three-dimensional vortex formation from domain-wall annihilations is considered a kink formation in subspace. Numerical experiments reveal that the subspatial dynamics obey the dynamic scaling law of phase-ordering kinetics. This model is experimentally feasible and provides insights into how the extra dimensions influence subspatial phase transition in higher-dimensional space.

  10. Bose-Einstein Condensation in Semiconductors: The Key Role of Dark Excitons

    SciTech Connect

    Combescot, Monique; Betbeder-Matibet, Odile; Combescot, Roland

    2007-10-26

    Bose-Einstein condensation in semiconductors is controlled by the nonelementary-boson nature of excitons. Pauli exclusion between the fermionic components of composite excitons produces dramatic exchange couplings between bright and dark states. In microcavities, where bright excitons and photons form polaritons, they force the condensate to be linearly polarized, as observed. In bulk, they also force linear polarization, but of dark states, due to interband Coulomb scatterings. To evidence this dark condensate, indirect processes are thus needed.

  11. Photon antibunching upon scattering by an atomic Bose-Einstein condensate

    SciTech Connect

    Ilichev, L. V. Chapovsky, P. L.

    2010-05-15

    Antibunching of photodetections from different modes is shown to arise when two quantized light modes are scattered by an atomic Bose-Einstein condensate. This effect appears because of the uncertainty in the position of the condensate wave function relative to the optical lattice formed by the light beams. It is shown how the information contained in the history of photodetections leads to a spatial localization of the condensate wave function.

  12. Bose-Einstein Condensation of Photons versus Lasing and Hanbury Brown-Twiss Measurements with a Condensate of Light

    NASA Astrophysics Data System (ADS)

    Schmitt, Julian; Damm, Tobias; Dung, David; Vewinger, Frank; Klaers, Jan; Weitz, Martin

    The advent of controlled experimental accessibility of Bose-Einstein condensates, as realized with e.g. cold atomic gases, exciton-polaritons, and more recently photons in a dye-filled optical microcavity, has paved the way for new studies and tests of a plethora of fundamental concepts in quantum physics. We here describe recent experiments studying a transition between laser-like dynamics and Bose-Einstein condensation of photons in the dye microcavity system. Further, measurements of the second-order coherence of the photon condensate are presented. In the condensed state we observe photon number fluctuations of order of the total particle number, as understood from effective particle exchange with the photo-excitable dye molecules. The observed intensity fluctuation properties give evidence for Bose-Einstein condensation occurring in the grand-canonical statistical ensemble regime.

  13. Limits to the analog Hawking temperature in a Bose-Einstein condensate

    SciTech Connect

    Wuester, S.; Savage, C. M.

    2007-07-15

    Quasi-one-dimensional outflow from a dilute gas Bose-Einstein condensate reservoir is a promising system for the creation of analog Hawking radiation. We use numerical modeling to show that stable sonic horizons exist in such a system under realistic conditions, taking into account the transverse dimensions and three-body loss. We find that loss limits the analog Hawking temperatures achievable in the hydrodynamic regime, with sodium condensates allowing the highest temperatures. A condensate of 30 000 atoms, with transverse confinement frequency {omega}{sub perpendicular}=6800x2{pi} Hz, yields horizon temperatures of about 20 nK over a period of 50 ms. This is at least four times higher than for other atoms commonly used for Bose-Einstein condensates.

  14. Three-dimensional parallel vortex rings in Bose-Einstein condensates

    SciTech Connect

    Crasovan, Lucian-Cornel; Perez-Garcia, Victor M.; Danaila, Ionut; Mihalache, Dumitru; Torner, Lluis

    2004-09-01

    We construct three-dimensional structures of topological defects hosted in trapped wave fields, in the form of vortex stars, vortex cages, parallel vortex lines, perpendicular vortex rings, and parallel vortex rings, and we show that the latter exist as robust stationary, collective states of nonrotating Bose-Einstein condensates. We discuss the stability properties of excited states containing several parallel vortex rings hosted by the condensate, including their dynamical and structural stability.

  15. Kelvin-Tkachenko waves of few-vortex arrays in trapped Bose-Einstein condensates

    SciTech Connect

    Simula, T. P.; Machida, K.

    2010-12-15

    We have calculated the low-lying elementary excitations of three-dimensional few-vortex arrays in trapped Bose-Einstein condensates. The number of different Kelvin-Tkachenko vortex wave branches found matches the number of vortices in the condensate. The lowest odd-parity modes exhibit superfluid gyroscopic vortex motion. Experimentally, these modes could be excited and observed individually or in connection with the formation and decay of quantum turbulence.

  16. 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.

  17. Spin-Orbit-Coupled Bose-Einstein Condensates in a One-Dimensional Optical Lattice

    NASA Astrophysics Data System (ADS)

    Hamner, C.; Zhang, Yongping; Khamehchi, M. A.; Davis, Matthew J.; Engels, P.

    2015-02-01

    We investigate a spin-orbit-coupled Bose-Einstein condensate loaded into a translating optical lattice. We experimentally demonstrate the lack of Galilean invariance in the spin-orbit-coupled system, which leads to anisotropic behavior of the condensate depending on the direction of translation of the lattice. The anisotropy is theoretically understood by an effective dispersion relation. We experimentally confirm this theoretical picture by probing the dynamical instability of the system.

  18. High-energy gravitational scattering and Bose-Einstein condensates of gravitons

    NASA Astrophysics Data System (ADS)

    Kühnel, Florian; Sundborg, Bo

    2014-12-01

    Quantum black holes are difficult to describe. We consider two seemingly divergent approaches, high-energy scattering and the proposal to regard black holes as Bose-Einstein condensates of gravitons, and establish a connection between them. Results from the eikonal approximation of high-energy scattering are reconsidered and processed further by a saddle-point approximation. The dominant contribution to the scattering amplitude comes from a ladder diagram with the exchange of N gravitons, and the number of gravitons follows a Poisson distribution. This approximation supports the picture of a graviton Bose-Einstein condensate with an extent equal to the Schwarzschild radius, which grows with N in a way determined by the saddle point. The approach permits calculations of 1 /N corrections from the fluctuations around the saddle points and we comment on these. Scattering methods might be useful probes of quantum black holes, especially when interpreted in terms of condensates.

  19. 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.

  20. Bose-Einstein Condensation of Long-Lifetime Polaritons in Thermal Equilibrium.

    PubMed

    Sun, Yongbao; Wen, Patrick; Yoon, Yoseob; Liu, Gangqiang; Steger, Mark; Pfeiffer, Loren N; West, Ken; Snoke, David W; Nelson, Keith A

    2017-01-06

    The experimental realization of Bose-Einstein condensation (BEC) with atoms and quasiparticles has triggered wide exploration of macroscopic quantum effects. Microcavity polaritons are of particular interest because quantum phenomena such as BEC and superfluidity can be observed at elevated temperatures. However, polariton lifetimes are typically too short to permit thermal equilibration. This has led to debate about whether polariton condensation is intrinsically a nonequilibrium effect. Here we report the first unambiguous observation of BEC of optically trapped polaritons in thermal equilibrium in a high-Q microcavity, evidenced by equilibrium Bose-Einstein distributions over broad ranges of polariton densities and bath temperatures. With thermal equilibrium established, we verify that polariton condensation is a phase transition with a well-defined density-temperature phase diagram. The measured phase boundary agrees well with the predictions of basic quantum gas theory.

  1. Bose-Einstein Condensation of Long-Lifetime Polaritons in Thermal Equilibrium

    NASA Astrophysics Data System (ADS)

    Sun, Yongbao; Wen, Patrick; Yoon, Yoseob; Liu, Gangqiang; Steger, Mark; Pfeiffer, Loren N.; West, Ken; Snoke, David W.; Nelson, Keith A.

    2017-01-01

    The experimental realization of Bose-Einstein condensation (BEC) with atoms and quasiparticles has triggered wide exploration of macroscopic quantum effects. Microcavity polaritons are of particular interest because quantum phenomena such as BEC and superfluidity can be observed at elevated temperatures. However, polariton lifetimes are typically too short to permit thermal equilibration. This has led to debate about whether polariton condensation is intrinsically a nonequilibrium effect. Here we report the first unambiguous observation of BEC of optically trapped polaritons in thermal equilibrium in a high-Q microcavity, evidenced by equilibrium Bose-Einstein distributions over broad ranges of polariton densities and bath temperatures. With thermal equilibrium established, we verify that polariton condensation is a phase transition with a well-defined density-temperature phase diagram. The measured phase boundary agrees well with the predictions of basic quantum gas theory.

  2. 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.

  3. Subluminal to superluminal propagation of an optical pulse in an f-deformed Bose Einstein condensate

    NASA Astrophysics Data System (ADS)

    Haghshenasfard, Z.; Naderi, M. H.; Soltanolkotabi, M.

    2008-08-01

    In this paper, we investigate the propagation of a weak optical probe pulse in an f-deformed Bose-Einstein condensate of a gas with the Λ-type three-level atoms in the electromagnetically induced transparency regime. We use an f-deformed generalization of an effective two-level quantum model of the three-level Λ configuration in which Gardiner's phonon operators for Bose-Einstein condensates are deformed by an operator-valued function, f(\\hat n), of the particle-number operator \\hat n. By making use of the quantum approach of the angular momentum theory, we obtain the eigenvalues and eigenfunctions of the system up to a first-order approximation. We consider the collisions between the atoms as a special kind of f-deformation. The collision rate κ is regarded as the deformation parameter and light propagation in the deformed Bose-Einstein condensate is analysed. In particular, we show that the absorptive and dispersive properties of the deformed condensate can be controlled effectively by changing the deformation parameter κ and the total number of atoms. We find that by increasing the value of κ the group velocity of the probe pulse changes, through deformed condensate, from subluminal to superluminal.

  4. 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.

  5. A Ring with a Spin: Superfluidity in a toroidal Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Ramanathan, Anand Krishnan

    2011-12-01

    Superfluidity is a remarkable phenomenon. Superfluidity was initially characterized by flow without friction, first seen in liquid helium in 1938, and has been studied extensively since. Superfluidity is believed to be related to, but not identical to Bose-Einstein condensation, a statistical mechanical phenomena predicted by Albert Einstein in 1924 based on the statistics of Satyendra Nath Bose, where bosonic atoms make a phase transition to form a Bose-Einstein condensate (BEC), a gas which has macroscopic occupation of a single quantum state. Developments in laser cooling of neutral atoms and the subsequent realization of Bose-Einstein condensates in ultracold gases have opened a new window into the study of superfluidity and its relation to Bose-Einstein condensation. In our atomic sodium BEC experiment, we studied superfluidity and dissipationless flow in an all-optical toroidal trap, constructed using the combination of a horizontal "sheet"-like beam and vertical "ring"-like beam, which, like a circuit loop, allows flow around the ring. On inducing a single quantum of circulation in the condensate, the smoothness and uniformity of the toroidal BEC enabled the sustaining of a persistent current lasting 40 seconds, limited by the lifetime of the BEC due to background gas pressure. This success set the stage for further experiments studying superfluidity. In a first set of experiments, we studied the stability of the persistent current by inserting a barrier in the flow path of the ring. The superflow stopped abruptly at a barrier strength such that the local flow velocity at the barrier exceeded a critical velocity, which supported decay via the creation of a vortex-antivortex pair. Our precise control in inducing and arresting superflow in the BEC is a first step toward studying other aspects of superfluidity, such as the effect of temperature and dimensionality. This thesis discusses these experiments and also details partial-transfer absorption imaging, an

  6. A novel experiment for coupling a Bose-Einstein condensate with two crossed cavity modes

    NASA Astrophysics Data System (ADS)

    Leonard, Julian; Morales, Andrea; Zupancic, Philip; Donner, Tobias; Esslinger, Tilman

    2015-05-01

    Over the last decade, combining cavity quantum electrodynamics and quantum gases made it possible to explore the coupling of quantized light fields to coherent matter waves, leading e.g. to new optomechanical phenomena and the realization of quantum phase transitions. Triggered by the interest to study setups with more complex cavity geometries, we built a novel, highly flexible experimental system for coupling a Bose-Einstein condensate (BEC) with optical cavities, which allows to switch the cavity setups by means of an interchangeable science platform. report on our latest results on coupling a Bose-Einstein condensate with two crossed cavity modes intersecting under an angle of 60°. The mirrors have been machined in a way to spatially approach them, thus obtaining maximum single atom coupling rates of several MHz. This setup will allow the study of self-ordered phases in different lattice shapes, such as hexagonal and triangular geometries.

  7. Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system

    NASA Astrophysics Data System (ADS)

    Hamide Kazemi, S.; Ghanbari, S.; Mahmoudi, M.

    2016-01-01

    The propagation of a probe laser field in a cavity optomechanical system with a Bose-Einstein condensate is studied. The transmission properties of the system are investigated and it is shown that the group velocity of the probe pulse field can be controlled by Rabi frequency of the pump laser field. The effect of the decay rate of the cavity photons on the group velocity is studied and it is demonstrated that for small values of the decay rates, the light propagation switches from subluminal to superluminal just by changing the Rabi frequency of the pump field. Then, the gain-assisted superluminal light propagation due to the cross-Kerr nonlinearity is established in cavity optomechanical system with a Bose-Einstein condensate. Such behavior can not appear in the pump-probe two-level atomic systems in the normal phase. We also find that the amplification is achieved without inversion in the population of the quantum energy levels.

  8. Spontaneous creation of Kibble-Zurek solitons in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Lamporesi, Giacomo; Donadello, Simone; Serafini, Simone; Dalfovo, Franco; Ferrari, Gabriele

    2013-10-01

    When a system crosses a second-order phase transition on a finite timescale, spontaneous symmetry breaking can cause the development of domains with independent order parameters, which then grow and approach each other creating boundary defects. This is known as the Kibble-Zurek mechanism. Originally introduced in cosmology, it applies to both classical and quantum phase transitions, in a wide variety of physical systems. Here we report on the spontaneous creation of solitons in Bose-Einstein condensates through the Kibble-Zurek mechanism. We measure the power-law dependence of defect number on the quench time, and show that lower atomic densities enhance defect formation. These results provide a promising test bed for the determination of critical exponents in Bose-Einstein condensates.

  9. 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.

  10. Finite-temperature dynamics of vortices in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Gautam, S.; Roy, Arko; Mukerjee, Subroto

    2014-01-01

    We study the dynamics of a single vortex and a pair of vortices in quasi two-dimensional Bose-Einstein condensates at finite temperatures. To this end, we use the stochastic Gross-Pitaevskii equation, which is the Langevin equation for the Bose-Einstein condensate. For a pair of vortices, we study the dynamics of both the vortex-vortex and vortex-antivortex pairs, which are generated by rotating the trap and moving the Gaussian obstacle potential, respectively. Due to thermal fluctuations, the constituent vortices are not symmetrically generated with respect to each other at finite temperatures. This initial asymmetry coupled with the presence of random thermal fluctuations in the system can lead to different decay rates for the component vortices of the pair, especially in the case of two corotating vortices.

  11. Spin-momentum coupled Bose-Einstein condensates with lattice band pseudospins.

    PubMed

    Khamehchi, M A; Qu, Chunlei; Mossman, M E; Zhang, Chuanwei; Engels, P

    2016-02-29

    The quantum emulation of spin-momentum coupling, a crucial ingredient for the emergence of topological phases, is currently drawing considerable interest. In previous quantum gas experiments, typically two atomic hyperfine states were chosen as pseudospins. Here, we report the observation of a spin-momentum coupling achieved by loading a Bose-Einstein condensate into periodically driven optical lattices. The s and p bands of a static lattice, which act as pseudospins, are coupled through an additional moving lattice that induces a momentum-dependent coupling between the two pseudospins, resulting in s-p hybrid Floquet-Bloch bands. We investigate the band structures by measuring the quasimomentum of the Bose-Einstein condensate for different velocities and strengths of the moving lattice, and compare our measurements to theoretical predictions. The realization of spin-momentum coupling with lattice bands as pseudospins paves the way for engineering novel quantum matter using hybrid orbital bands.

  12. Bose-Einstein condensation in an electro-pneumatically transformed quadrupole-Ioffe magnetic trap

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Sarkar, Sumit; Verma, Gunjan; Vishwakarma, Chetan; Noaman, Md; Rapol, Umakant

    2015-02-01

    We report a novel approach for preparing a Bose-Einstein condensate (BEC) of 87Rb atoms using an electro-pneumatically driven transfer of atoms into a quadrupole-Ioffe magnetic trap (QUIC trap). More than 5 × {{10}8} atoms from a magneto-optical trap are loaded into a spherical quadrupole trap and then transferred into an Ioffe trap by moving the Ioffe coil towards the center of the quadrupole coil thereby changing the distance between the quadrupole trap center and the Ioffe coil. The transfer efficiency is more than 80%. This approach is different from the conventional approach of loading the atoms into a QUIC trap wherein the spherical quadrupole trap is transformed into a QUIC trap by changing the currents in the quadrupole and the Ioffe coils. The phase space density is then increased by forced rf evaporative cooling to achieve Bose-Einstein condensation of more than 105 atoms.

  13. Developing density functional theory for Bose-Einstein condensates. The case of chemical bonding

    SciTech Connect

    Putz, Mihai V.

    2015-01-22

    Since the nowadays growing interest in Bose-Einstein condensates due to the expanded experimental evidence on various atomic systems within optical lattices in weak and strong coupling regimes, the connection with Density Functional Theory is firstly advanced within the mean field framework at three levels of comprehension: the many-body normalization condition, Thomas-Fermi limit, and the chemical hardness closure with the inter-bosonic strength and universal Hohenberg-Kohn functional. As an application the traditional Heitler-London quantum mechanical description of the chemical bonding for homopolar atomic systems is reloaded within the non-linear Schrödinger (Gross-Pitaevsky) Hamiltonian; the results show that a two-fold energetic solution is registered either for bonding and antibonding states, with the bosonic contribution being driven by the square of the order parameter for the Bose-Einstein condensate density in free (gas) motion, while the associate wave functions remain as in classical molecular orbital model.

  14. Bose-Einstein condensation in low dimensional systems with deformed bosons

    NASA Astrophysics Data System (ADS)

    Algin, Abdullah; Olkun, Ali

    2017-08-01

    We study the low and high temperature thermostatistical properties of a deformed boson gas constructed by the bosonic intermediate-statistics particles confined in low spatial dimensions. Many of the deformed thermodynamical functions of the system such as internal energy and entropy are investigated by means of some elements of the Fibonacci calculus. Particular emphasis is given to a careful analysis on low dimensional systems of such deformed bosons, and the conditions under which the Bose-Einstein condensation would occur in such systems are discussed. We show that low dimensional systems with deformed bosons exhibit the Bose-Einstein condensation for values of the model deformation parameters (p , q) greater than one. We also study possible anyonic behavior of the model for high temperatures. The results obtained in this work reveal that the present deformed boson gas model can be used for modeling nonlinear behavior of systems with quasiparticles encountered in several areas of research particularly in quantum science.

  15. 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.

  16. Spin-momentum coupled Bose-Einstein condensates with lattice band pseudospins

    PubMed Central

    Khamehchi, M. A.; Qu, Chunlei; Mossman, M. E.; Zhang, Chuanwei; Engels, P.

    2016-01-01

    The quantum emulation of spin-momentum coupling, a crucial ingredient for the emergence of topological phases, is currently drawing considerable interest. In previous quantum gas experiments, typically two atomic hyperfine states were chosen as pseudospins. Here, we report the observation of a spin-momentum coupling achieved by loading a Bose-Einstein condensate into periodically driven optical lattices. The s and p bands of a static lattice, which act as pseudospins, are coupled through an additional moving lattice that induces a momentum-dependent coupling between the two pseudospins, resulting in s–p hybrid Floquet-Bloch bands. We investigate the band structures by measuring the quasimomentum of the Bose-Einstein condensate for different velocities and strengths of the moving lattice, and compare our measurements to theoretical predictions. The realization of spin-momentum coupling with lattice bands as pseudospins paves the way for engineering novel quantum matter using hybrid orbital bands. PMID:26924575

  17. Entropy density of an adiabatic relativistic Bose-Einstein condensate star

    SciTech Connect

    Khaidir, Ahmad Firdaus; Kassim, Hasan Abu; Yusof, Norhasliza

    2015-04-24

    Inspired by recent works, we investigate how the thermodynamics parameters (entropy, temperature, number density, energy density, etc) of Bose-Einstein Condensate star scale with the structure of the star. Below the critical temperature in which the condensation starts to occur, we study how the entropy behaves with varying temperature till it reaches its own stability against gravitational collapse and singularity. Compared to photon gases (pressure is described by radiation) where the chemical potential, μ is zero, entropy of photon gases obeys the Stefan-Boltzmann Law for a small values of T while forming a spiral structure for a large values of T due to general relativity. The entropy density of Bose-Einstein Condensate is obtained following the similar sequence but limited under critical temperature condition. We adopt the scalar field equation of state in Thomas-Fermi limit to study the characteristics of relativistic Bose-Einstein condensate under varying temperature and entropy. Finally, we obtain the entropy density proportional to (σT{sup 3}-3T) which obeys the Stefan-Boltzmann Law in ultra-relativistic condition.

  18. Kinetic description of Bose-Einstein condensation with test particle simulations

    NASA Astrophysics Data System (ADS)

    Zhou, Kai; Xu, Zhe; Zhuang, Pengfei; Greiner, Carsten

    2017-07-01

    We present a kinetic description of Bose-Einstein condensation for particle systems being out of thermal equilibrium, which may happen for gluons produced in the early stage of ultrarelativistic heavy-ion collisions. The dynamics of bosons towards equilibrium is described by a Boltzmann equation including Bose factors. To solve the Boltzmann equation with the presence of a Bose-Einstein condensate we make further developments of the kinetic transport model BAMPS (Boltzmann approach of multiparton scatterings). In this work we demonstrate the correct numerical implementations by comparing the final numerical results to the expected solutions at thermal equilibrium for systems with and without the presence of Bose-Einstein condensate. In addition, the onset of the condensation in an overpopulated gluon system is studied in more details. We find that both expected power-law scalings denoted by the particle and energy cascade are observed in the calculated gluon distribution function at infrared and intermediate momentum regions, respectively. Also, the time evolution of the hard scale exhibits a power-law scaling in a time window, which indicates that the distribution function is approximately self-similar during that time.

  19. 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.

  20. Analysis and calibration of absorptive images of Bose-Einstein condensate at nonzero temperatures

    SciTech Connect

    Szczepkowski, J.; Gartman, R.; Zawada, M.; Witkowski, M.; Tracewski, L.; Gawlik, W.

    2009-05-15

    We describe the method allowing quantitative interpretation of absorptive images of mixtures of Bose-Einstein condensate and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction and eliminates arbitrariness of most of the previous approaches. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group.

  1. Stability of the half-vortex in spin-orbit coupled Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Wu, Rukuan

    2016-12-01

    The half-vortex stability of the stripe phase in spin-orbit (SO) coupled Bose-Einstein condensate (BEC) is discussed through the multi-mode theory. We find that when the energy of the Rabi coupling is close to zero, the half-vortex in the trap center is always dynamically stable; when the energy becomes larger, the vortex may be structurally unstable. Both of the results are confirmed by the numerical simulation of the full Gross-Pitaevskii equation.

  2. Binary Quantum Turbulence Arising from Countersuperflow Instability in Two-Component Bose-Einstein Condensates

    SciTech Connect

    Takeuchi, Hiromitsu; Ishino, Shungo; Tsubota, Makoto

    2010-11-12

    We theoretically study the development of quantum turbulence from two counter-propagating superfluids of miscible Bose-Einstein condensates by numerically solving the coupled Gross-Pitaevskii equations. When the relative velocity exceeds a critical value, the countersuperflow becomes unstable and quantized vortices are nucleated, which leads to isotropic quantum turbulence consisting of two superflows. It is shown that the binary turbulence can be realized experimentally in a trapped system.

  3. Binary quantum turbulence arising from countersuperflow instability in two-component Bose-Einstein condensates.

    PubMed

    Takeuchi, Hiromitsu; Ishino, Shungo; Tsubota, Makoto

    2010-11-12

    We theoretically study the development of quantum turbulence from two counter-propagating superfluids of miscible Bose-Einstein condensates by numerically solving the coupled Gross-Pitaevskii equations. When the relative velocity exceeds a critical value, the countersuperflow becomes unstable and quantized vortices are nucleated, which leads to isotropic quantum turbulence consisting of two superflows. It is shown that the binary turbulence can be realized experimentally in a trapped system.

  4. Oblique Dark Solitons in Supersonic Flow of a Bose-Einstein Condensate

    SciTech Connect

    El, G. A.; Gammal, A.; Kamchatnov, A. M.

    2006-11-03

    In the framework of the Gross-Pitaevskii mean field approach, it is shown that the supersonic flow of a Bose-Einstein condensate can support a new type of pattern--an oblique dark soliton. The corresponding exact solution of the Gross-Pitaevskii equation is obtained. It is demonstrated by numerical simulations that oblique solitons can be generated by an obstacle inserted into the flow.

  5. Nucleation and growth of vortices in a rotating Bose-Einstein condensate.

    PubMed

    Vorov, O K; Isacker, P Van; Hussein, M S; Bartschat, K

    2005-12-02

    An analytic solution of the Gross-Pitaevskii equation for a rotating Bose-Einstein condensate of trapped atoms describes the onset of vorticity when the rotational speed is increased, starting with the entry of the first vortex and followed by the formation of growing symmetric Wigner molecules. It explains the staircase of angular momentum jumps and the behavior of the bosonic occupancies observed in numerical studies. The similarity of this behavior and mesoscopic superconductors is discussed.

  6. Oblique dark solitons in supersonic flow of a Bose-Einstein condensate.

    PubMed

    El, G A; Gammal, A; Kamchatnov, A M

    2006-11-03

    In the framework of the Gross-Pitaevskii mean field approach, it is shown that the supersonic flow of a Bose-Einstein condensate can support a new type of pattern--an oblique dark soliton. The corresponding exact solution of the Gross-Pitaevskii equation is obtained. It is demonstrated by numerical simulations that oblique solitons can be generated by an obstacle inserted into the flow.

  7. 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.

  8. Nucleation and Growth of Vortices in a Rotating Bose-Einstein Condensate

    SciTech Connect

    Vorov, O.K.; Van Isacker, P.; Hussein, M. S.; Bartschat, K.

    2005-12-02

    An analytic solution of the Gross-Pitaevskii equation for a rotating Bose-Einstein condensate of trapped atoms describes the onset of vorticity when the rotational speed is increased, starting with the entry of the first vortex and followed by the formation of growing symmetric Wigner molecules. It explains the staircase of angular momentum jumps and the behavior of the bosonic occupancies observed in numerical studies. The similarity of this behavior and mesoscopic superconductors is discussed.

  9. Phase-diffusion dynamics in weakly coupled bose-einstein condensates.

    PubMed

    Boukobza, Erez; Chuchem, Maya; Cohen, Doron; Vardi, Amichay

    2009-05-08

    We study the phase sensitivity of collisional phase diffusion between weakly coupled Bose-Einstein condensates, using a semiclassical picture of the two-mode Bose-Hubbard model. When weak coupling is allowed, zero relative phase locking is attained in the Josephson-Fock transition regime, whereas a pi relative phase is only locked in Rabi-Josephson point. Our analytic semiclassical estimates agree well with the numerical results.

  10. Controlling chaos in the Bose-Einstein condensate system of a double lattice

    SciTech Connect

    Wang Zhixia Ni Zhengguo; Cong Fuzhong; Liu Xueshen; Chen Lei

    2011-02-15

    We study the chaotic dynamics in the Bose-Einstein condensate (BEC) system of a double lattice. Chaotic space-time evolution is investigated for the particle number density in a BEC. By changing of the s-wave scattering length with a Feshbach resonance, the chaotic behavior can be well controlled to enter into periodicity. Numerical calculation shows that there is periodic orbit according to the s-wave scattering length only if the maximal Lyapunov exponent of the system is negative.

  11. 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.

  12. Local management of the nonlinearity of Bose-Einstein condensates with pinched potentials

    NASA Astrophysics Data System (ADS)

    Guerreiro, A.; Silva, Nuno A.

    2016-12-01

    We present a proposal for the local control of the nonlinearity in quasi-one-dimensional Bose-Einstein condensates induced by a local pinching of the transverse confining potential. We investigate the scattering of bright matter-wave solitons through a pinched potential using numerical simulations of the full three-dimensional Gross-Pitaevskii equation and the corresponding effective one-dimensional model with spatially varying nonlinearity.

  13. Phase-Diffusion Dynamics in Weakly Coupled Bose-Einstein Condensates

    SciTech Connect

    Boukobza, Erez; Vardi, Amichay; Chuchem, Maya; Cohen, Doron

    2009-05-08

    We study the phase sensitivity of collisional phase diffusion between weakly coupled Bose-Einstein condensates, using a semiclassical picture of the two-mode Bose-Hubbard model. When weak coupling is allowed, zero relative phase locking is attained in the Josephson-Fock transition regime, whereas a {pi} relative phase is only locked in Rabi-Josephson point. Our analytic semiclassical estimates agree well with the numerical results.

  14. Zero-energy states in rotating trapped Bose-Einstein condensates.

    PubMed

    Simula, Tapio

    2013-07-17

    We have calculated low-lying quasiparticle excitation spectra of rotating three-dimensional Bose-Einstein condensates. We find, as opposed to the prediction of hydrodynamic continuum theories, a minimum in the Tkachenko mode spectrum at intermediate rotation frequencies of the harmonic trap. Such a minimum can harbour a Tkachenko quasiparticle with zero excitation energy. We discuss the experimental signatures of such a zero mode.

  15. Evolution of a dark soliton in a parabolic potential: Application to Bose-Einstein condensates

    SciTech Connect

    Brazhnyi, V.A.; Konotop, V.V.

    2003-10-01

    Evolution of a dark soliton in a one-dimensional Bose-Einstein condensate trapped by a harmonic potential is studied analytically and numerically. In the case of a deep soliton, main characteristics of its motion such as frequency and amplitude of oscillations are calculated by means of the perturbation theory which in the leading order results in a Newtonian dynamics, corrections to which are computed as well.

  16. Driving Defect Modes of Bose-Einstein Condensates in Optical Lattices

    SciTech Connect

    Brazhnyi, Valeriy A.; Konotop, Vladimir V.; Perez-Garcia, Victor M.

    2006-02-17

    We present an approximate analytical theory and direct numerical computation of defect modes of a Bose-Einstein condensate loaded in an optical lattice and subject to an additional localized (defect) potential. Some of the modes are found to be remarkably stable and can be driven along the lattice by means of a defect moving following a steplike function defined by the period of Josephson oscillations and the macroscopic stability of the atoms.

  17. 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.

  18. 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

  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. Dirac monopoles and dipoles in ferromagnetic spinor Bose-Einstein condensates

    SciTech Connect

    Savage, C.M.; Ruostekoski, J.

    2003-10-01

    We investigate a radial spin hedgehog, analogous to the Dirac monopole, in an optically trapped atomic spin-1 Bose-Einstein condensate. By joining together a monopole-antimonopole pair, we may form a vortex line with free ends. We numerically simulate the three-dimensional dynamics and imaginary time relaxation of these structures to nonsingular textures and show that they can be observable for realistic experimental parameters.

  2. Effect of impurities on the vortex lattice in Bose-Einstein condensates on optical lattice

    NASA Astrophysics Data System (ADS)

    Mithun, T.; Porsezian, K.; Dey, Bishwajyoti

    2015-06-01

    We numerically solve the Gross-Pitaeveskii equation to study the Bose-Einstein condensate in the rotating harmonical tarp and co-rotating optical lattice. The effect of a pinning site or impurity shows that it is able to move the vortex lattice center to either left or right depending on the position of the impurity. Also, it is observed that the impurity at the random positions can destroy the vortex lattice and the resulting disordered lattice has more energy.

  3. 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.

  4. Vortex force in compressible spin-orbit-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Toikka, L. A.

    2017-09-01

    Using a (1+2)-dimensional boson-vortex duality between nonlinear electrodynamics and a two-component compressible Bose-Einstein condensate with spin-orbit (SO) coupling, we obtain hydrodynamic continuity and Euler equations where the phase defect and nondefect degrees of freedom enter separately, and a separate equation encompassing quantization of circulation. We obtain the generalized force on vortices under SO coupling, and associate the linear confinement of vortices due to SO coupling with instanton fluctuations of the dual theory.

  5. 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.

  6. 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.

  7. Dipole oscillations of a Bose-Einstein condensate in the presence of defects and disorder.

    PubMed

    Albert, M; Paul, T; Pavloff, N; Leboeuf, P

    2008-06-27

    We consider dipole oscillations of a trapped dilute Bose-Einstein condensate in the presence of a scattering potential consisting either in a localized defect or in an extended disordered potential. In both cases the breaking of superfluidity and the damping of the oscillations are shown to be related to the appearance of a nonlinear dissipative flow. At supersonic velocities the flow becomes asymptotically dissipationless.

  8. Coherent Atom Optics with Optical Potentials: A Summary of New Phenomena with Bose-Einstein Condensates at the University of Arizona

    DTIC Science & Technology

    2009-10-08

    Coherent atom optics with optical potentials: a summary of new phenomena with Bose- Einstein Condensates at the University of Arizona Final Project...AZ Abstract The Bose- Einstein condensation (BEC) laboratory at the University of Arizona has built a program of research that focuses on two areas of...universities and experimental work in Arizona progressing in tandem. Project report Among the research goals of the Bose- Einstein condensation lab at

  9. 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.

  10. 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.

  11. Spontaneous formation and nonequilibrium dynamics of a soliton-shaped Bose-Einstein condensate in a trap.

    PubMed

    Berman, Oleg L; Kezerashvili, Roman Ya; Kolmakov, German V; Pomirchi, Leonid M

    2015-06-01

    The Bose-stimulated self-organization of a quasi-two-dimensional nonequilibrium Bose-Einstein condensate in an in-plane potential is proposed. We obtained the solution of the nonlinear, driven-dissipative Gross-Pitaevskii equation for a Bose-Einstein condensate trapped in an external asymmetric parabolic potential within the method of the spectral expansion. We found that, in sharp contrast to previous observations, the condensate can spontaneously acquire a solitonlike shape for spatially homogeneous pumping. This condensate soliton performs oscillatory motion in a parabolic trap and, also, can spontaneously rotate. Stability of the condensate soliton in the spatially asymmetric trap is analyzed. In addition to the nonlinear dynamics of nonequilibrium Bose-Einstein condensates of ultracold atoms, our findings can be applied to the condensates of quantum well excitons and cavity polaritons in semiconductor heterostructure, and to the condensates of photons.

  12. Bose-Einstein condensates in the presence of Weyl spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Wu, Ting; Liao, Renyuan

    2017-01-01

    We consider two-component Bose-Einstein condensates subject to Weyl spin-orbit coupling. We obtain mean-field ground state phase diagram by variational method. In the regime where interspecies coupling is larger than intraspecies coupling, the system is found to be fully polarized and condensed at a finite momentum lying along the quantization axis. We characterize this phase by studying the excitation spectrum, the sound velocity, the quantum depletion of condensates, the shift of ground state energy, and the static structure factor. We find that spin-orbit coupling and interspecies coupling generally leads to competing effects.

  13. 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.

  14. A Phenomenological Model of the Growth of Two-Species Atomic Bose-Einstein Condensates

    NASA Astrophysics Data System (ADS)

    Pattinson, R. W.; Parker, N. G.; Proukakis, N. P.

    2014-04-01

    We introduce a phenomenological mean-field model to describe the growth of immiscible two-species atomic Bose-Einstein condensates towards some equilibrium. Our model is based on the coupled Gross-Pitaevskii equations with the addition of dissipative terms to account for growth. While our model may be applied generally, we take a recent Rb-Cs experiment [McCarron et al., Phys. Rev. A 84 011603(R) (2011)] as a case study. As the condensates grow, they can pass through ranging transient density structures which can be distinct from the equilibrium states, although such a model always predicts the predominance of one condensate species over longer evolution times.

  15. 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.

  16. Bose-Einstein condensate on a persistent-supercurrent atom chip

    NASA Astrophysics Data System (ADS)

    Imai, Hiromitsu; Inaba, Kensuke; Tanji-Suzuki, Haruka; Yamashita, Makoto; Mukai, Tetsuya

    2014-09-01

    A Bose-Einstein condensate was achieved in a stable magnetic trap on a persistent-supercurrent atom chip with a superconducting closed-loop circuit. We determined precisely the shape of the magnetic trapping potential by systematically controlling the persistent supercurrent. The condensation was verified by time-of-flight imaging and by atom number decay measurements. The measured decay rates agreed quantitatively with numerical simulations on the three-body loss process assuming all of the atoms to be a condensate. We also discuss the feasibility of creating a quasi-one-dimensional Bose gas on our atom chip.

  17. 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.

  18. Atom Michelson Interferometer on a Chip Using a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Wang, Ying-Ju; Anderson, Dana Z.; Bright, Victor M.; Cornell, Eric A.; Diot, Quentin; Kishimoto, Tetsuo; Prentiss, Mara; Saravanan, R. A.; Segal, Stephen R.; Wu, Saijun

    2005-03-01

    An atom Michelson interferometer is implemented on an “atom chip.” The chip uses lithographically patterned conductors and external magnetic fields to produce and guide a Bose-Einstein condensate. Splitting, reflecting, and recombining of condensate atoms are achieved by a standing-wave light field having a wave vector aligned along the atom waveguide. A differential phase shift between the two arms of the interferometer is introduced by either a magnetic-field gradient or with an initial condensate velocity. Interference contrast is still observable at 20% with an atom propagation time of 10 ms.

  19. Atom Michelson interferometer on a chip using a Bose-Einstein condensate.

    PubMed

    Wang, Ying-Ju; Anderson, Dana Z; Bright, Victor M; Cornell, Eric A; Diot, Quentin; Kishimoto, Tetsuo; Prentiss, Mara; Saravanan, R A; Segal, Stephen R; Wu, Saijun

    2005-03-11

    An atom Michelson interferometer is implemented on an "atom chip." The chip uses lithographically patterned conductors and external magnetic fields to produce and guide a Bose-Einstein condensate. Splitting, reflecting, and recombining of condensate atoms are achieved by a standing-wave light field having a wave vector aligned along the atom waveguide. A differential phase shift between the two arms of the interferometer is introduced by either a magnetic-field gradient or with an initial condensate velocity. Interference contrast is still observable at 20% with an atom propagation time of 10 ms.

  20. 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.

  1. Bogoliubov theory of acoustic Hawking radiation in Bose-Einstein condensates

    SciTech Connect

    Recati, A.; Pavloff, N.; Carusotto, I.

    2009-10-15

    We apply the microscopic Bogoliubov theory of dilute Bose-Einstein condensates to analyze quantum and thermal fluctuations in a flowing atomic condensate in the presence of a sonic horizon. For the simplest case of a step-like horizon, closed-form analytical expressions are found for the spectral distribution of the analog Hawking radiation and for the density correlation function. The peculiar long-distance density correlations that appear as a consequence of the Hawking emission features turns out to be reinforced by a finite initial temperature of the condensate. The analytical results are in good quantitative agreement with first principle numerical calculations.

  2. Size and dynamics of vortex dipoles in dilute Bose-Einstein condensates

    SciTech Connect

    Kuopanportti, Pekko; Huhtamaeki, Jukka A. M.

    2011-01-15

    Recently, Freilich et al. [Science 329, 1182 (2010)] experimentally discovered stationary states of vortex dipoles, pairs of vortices of opposite circulation, in dilute Bose-Einstein condensates. To explain their observations, we perform simulations based on the Gross-Pitaevskii equation and obtain excellent quantitative agreement on the size of the stationary dipole. We also investigate how their imaging method, in which atoms are repeatedly extracted from a single condensate, affects the vortex dynamics. We find that it mainly induces isotropic size oscillations of the condensate without otherwise disturbing the vortex trajectories. Thus, the imaging technique appears to be a promising tool for studying real-time superfluid dynamics.

  3. 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.

  4. 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.

  5. Sound propagation in a Bose-Einstein condensate at finite temperatures

    SciTech Connect

    Meppelink, R.; Koller, S. B.; Straten, P. van der

    2009-10-15

    We study the propagation of a density wave in a magnetically trapped Bose-Einstein condensate at finite temperatures. The thermal cloud is in the hydrodynamic regime and the system is therefore described by the two-fluid model. A phase-contrast imaging technique is used to image the cloud of atoms and allows us to observe small density excitations. The propagation of the density wave in the condensate is used to determine the speed of sound as a function of the temperature. We find the speed of sound to be in good agreement with calculations based on the Landau two-fluid model.

  6. 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.

  7. 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.

  8. Non-autonomous bright matter wave solitons in spinor Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Kanna, T.; Babu Mareeswaran, R.; Sakkaravarthi, K.

    2014-01-01

    We investigate the dynamics of bright matter wave solitons in spin-1 Bose-Einstein condensates with time modulated nonlinearities. We obtain soliton solutions of an integrable autonomous three-coupled Gross-Pitaevskii (3-GP) equations using Hirota's method involving a non-standard bilinearization. The similarity transformations are developed to construct the soliton solutions of non-autonomous 3-GP system. The non-autonomous solitons admit different density profiles. An interesting phenomenon of soliton compression is identified for kink-like nonlinearity coefficient with Hermite-Gaussian-like potential strength. Our study shows that these non-autonomous solitons undergo non-trivial collisions involving condensate switching.

  9. 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.

  10. Reduced dimensionality and spatial entanglement in highly anisotropic Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Tacla, Alexandre B.; Caves, Carlton M.

    2014-07-01

    We investigate the reduced dimensionality of highly anisotropic Bose-Einstein condensates (BECs) in connection with the entanglement between the spatial degrees of freedom. We argue that the reduced dimensionality of the BEC is physically meaningful in a regime where spatial correlations are negligible. We handle the problem analytically within the mean-field approximation for general quasi-one-dimensional and quasi-two-dimensional geometries and obtain the optimal reduced-dimension, pure-state description of the condensate mean field. We give explicit solutions for the case of harmonic potentials, which we compare against exact numerical integration of the three-dimensional Gross-Pitaevskii equation.

  11. Bragg spectroscopy of the multibranch Bogoliubov spectrum of elongated Bose-Einstein condensates.

    PubMed

    Steinhauer, J; Katz, N; Ozeri, R; Davidson, N; Tozzo, C; Dalfovo, F

    2003-02-14

    We measure the response of an elongated Bose-Einstein condensate to a two-photon Bragg pulse. If the duration of the pulse is long, the total momentum transferred to the condensate exhibits a nontrivial behavior which reflects the structure of the underlying Bogoliubov spectrum. It is thus possible to perform a spectroscopic analysis in which axial phonons with a different number of radial nodes are resolved. The local density approximation is shown to fail in this regime, while the observed data agree well with the results of simulations based on the numerical solution of the Gross-Pitaevskii equation.

  12. Zero Kelvin Big Bang, an Alternative Paradigm: II. Bose-Einstein condensation and the Primeval Atom

    NASA Astrophysics Data System (ADS)

    Haynes, Royce

    2011-11-01

    In the first of a series of three papers, we described how logic suggests a "cosmic fabric" as the starting point for our universe: a sparse distribution of spin-oriented hydrogen atoms at zero kelvin, perhaps infinite and (almost) eternal. This second paper describes how a portion of this cosmic fabric could have condensed into a Bose-Einstein condensate (BEC). This cold ball of highly concentrated matter may be the "primeval atom" proposed by Georges Lemaître in 1931, as the beginning of our universe.

  13. 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.

  14. Reaching the hydrodynamic regime in a Bose-Einstein condensate by suppression of avalanches

    SciTech Connect

    Stam, K. M. R. van der; Meppelink, R.; Vogels, J. M.; Straten, P. van der

    2007-03-15

    We report the realization of a Bose-Einstein condensate (BEC) in the hydrodynamic regime. The hydrodynamic regime is reached by evaporative cooling at a relatively low density suppressing the effect of avalanches. With the suppression of avalanches a BEC containing more than 10{sup 8} atoms is produced. The collisional opacity can be tuned from the collisionless regime to a collisional opacity of more than 2 by compressing the trap after condensation. In the collisional opaque regime a significant heating of the cloud at time scales shorter than half of the radial trap period is measured, which is a direct proof that the BEC is hydrodynamic.

  15. Realization of a Sonic Black Hole Analog in a Bose-Einstein Condensate

    SciTech Connect

    Lahav, Oren; Itah, Amir; Blumkin, Alex; Gordon, Carmit; Rinott, Shahar; Zayats, Alona; Steinhauer, Jeff

    2010-12-10

    We have created an analog of a black hole in a Bose-Einstein condensate. In this sonic black hole, sound waves, rather than light waves, cannot escape the event horizon. A steplike potential accelerates the flow of the condensate to velocities which cross and exceed the speed of sound by an order of magnitude. The Landau critical velocity is therefore surpassed. The point where the flow velocity equals the speed of sound is the sonic event horizon. The effective gravity is determined from the profiles of the velocity and speed of sound. A simulation finds negative energy excitations, by means of Bragg spectroscopy.

  16. Elementary excitations of a Bose-Einstein condensate in an effective magnetic field

    SciTech Connect

    Murray, D. R.; Barnett, Stephen M.; Oehberg, P.; Gomila, Damia

    2007-11-15

    We calculate the low-energy elementary excitations of a Bose-Einstein condensate in an effective magnetic field. The field is created by the interplay between light beams carrying orbital angular momentum and the trapped atoms [G. Juzeliunas et al., Phys. Rev. A 71, 053614 (2005)]. We examine the role of the homogeneous magnetic field, familiar from studies of rotating condensates, and also investigate spectra for vector potentials with a more general radial dependence. We discuss the instabilities which arise and how these may be manifested.

  17. A Kinetic Approach to Bose-Einstein Condensates: Self-Phase Modulation and Bogoliubov Oscillations

    SciTech Connect

    Mendonca, J.T.; Bingham, R.; Shukla, P.K.

    2005-11-01

    A kinetic approach to Bose-Einstein condensates (BECs) is proposed based on the Wigner-Moyal equation (WME). In the semiclassical limit, the WME reduces to the particle-number conservation equation. Two examples of applications are (i) a self-phase modulation of a BE condensate beam, where we show that part of the beam is decelerated and eventually stops as a result of the gradient of the effective self-potential, and (ii) the derivation of a kinetic dispersion relation for sound waves in BECs, including collisionless Landau damping.

  18. Diffraction of a Bose-Einstein Condensate from a Magnetic Lattice on a Microchip

    SciTech Connect

    Guenther, A.; Kraft, S.; Kemmler, M.; Koelle, D.; Kleiner, R.; Zimmermann, C.; Fortagh, J.

    2005-10-21

    We experimentally study the diffraction of a Bose-Einstein condensate from a magnetic lattice, realized by a set of 372 parallel gold conductors which are microfabricated on a silicon substrate. The conductors generate a periodic potential for the atoms with a lattice constant of 4 {mu}m. After exposing the condensate to the lattice for several milliseconds we observe diffraction up to fifth order by standard time of flight imaging techniques. The experimental data can be quantitatively interpreted with a simple phase imprinting model. The demonstrated diffraction grating offers promising perspectives for the construction of an integrated atom interferometer.

  19. Creation and dynamics of two-dimensional skyrmions in antiferromagnetic spin-1 Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ollikainen, T.; Ruokokoski, E.; Möttönen, M.

    2014-03-01

    We numerically simulate the creation process of two-dimensional skyrmionic excitations in antiferromagnetic spin-1 Bose-Einstein condensates by solving the full three-dimensional dynamics of the system from the Gross-Pitaevskii equation. Our simulations reproduce quantitatively the experimental results of Choi et al. [Phys. Rev. Lett. 108, 035301 (2012), 10.1103/PhysRevLett.108.035301] without any fitting parameters. Furthermore, we examine the stability of the skyrmion by computing the temporal evolution of the condensate in a harmonic potential. The presence of both the quadratic Zeeman effect and dissipation in the simulations is vital for reproducing the experimentally observed decay time.

  20. Metastable helium Bose-Einstein condensate with a large number of atoms

    SciTech Connect

    Tychkov, A. S.; Jeltes, T.; McNamara, J. M.; Tol, P. J. J.; Herschbach, N.; Hogervorst, W.; Vassen, W.

    2006-03-15

    We have produced a Bose-Einstein condensate of metastable helium ({sup 4}He*) containing over 1.5x10{sup 7} atoms, which is a factor of 25 higher than previously achieved. The improved starting conditions for evaporative cooling are obtained by applying one-dimensional Doppler cooling inside a magnetic trap. The same technique is successfully used to cool the spin-polarized fermionic isotope ({sup 3}He*), for which thermalizing collisions are highly suppressed. Our detection techniques include absorption imaging, time-of-flight measurements on a microchannel plate detector, and ion counting to monitor the formation and decay of the condensate.

  1. Bose-Einstein condensation of Sr88 through sympathetic cooling with Sr87

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    We report Bose-Einstein condensation of Sr88, which has a small, negative s-wave scattering length (a88=-2a0). We overcome the poor evaporative cooling characteristics of this isotope by sympathetic cooling with Sr87 atoms. Sr87 is effective in this role despite the fact that it is a fermion because of the large ground-state degeneracy arising from a nuclear spin of I=9/2, which reduces the impact of Pauli blocking of collisions. We observe a limited number of atoms in the condensate (Nmax≈104) that is consistent with the value of a88 and the optical dipole trap parameters.

  2. Rotational fluxons of Bose-Einstein condensates in coplanar double-ring traps

    SciTech Connect

    Brand, J.; Haigh, T. J.; Zuelicke, U.

    2009-07-15

    Rotational analogs to magnetic fluxons in conventional Josephson junctions are predicted to emerge in the ground state of rotating tunnel-coupled annular Bose-Einstein condensates (BECs). Such topological condensate-phase structures can be manipulated by external potentials. We determine conditions for observing macroscopic quantum tunneling of a fluxon. Rotational fluxons in double-ring BECs can be created, manipulated, and controlled by external potentials in different ways than is possible in the solid-state system, thus rendering them a promising candidate system for studying and utilizing quantum properties of collective many-particle degrees of freedom.

  3. 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.

  4. Quantum Enhancement of Higher-Order Phononlike Excitations of a Bose-Einstein Condensate

    SciTech Connect

    Rowen, E. E.; Bar-Gill, N.; Davidson, N.

    2008-07-04

    In a Bose-Einstein condensate, the excitation of a Bogoliubov phonon with low momentum (e.g., by a two-photon Bragg process) is strongly suppressed due to destructive interference between two indistinguishable excitation pathways. Here we show that scattering of this sound excitation into a double-momentum mode is strongly enhanced due to constructive interference. This enhancement yields an inherent amplification of second-order sound excitations of the condensate, as we confirm experimentally. We further show that due to parity considerations, this effect is extended to higher-order excitations.

  5. 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.

  6. Role of quantum statistics in the photoassociation of Bose-Einstein condensates

    SciTech Connect

    Olsen, M. K.; Plimak, L. I.

    2003-09-01

    We show that the photoassociation of an atomic Bose-Einstein condensate to form condensed molecules is a chemical process which not only does not obey the Arrhenius rules for chemical reactions, but that it can also depend on the quantum statistics of the reactants. Comparing the predictions of a truncated Wigner representation for different initial quantum states, we find that, even when the quantum prediction for an initial coherent state is close to the Gross-Pitaevskii prediction, other quantum states may result in very different dynamics.

  7. Realization of a sonic black hole analog in a Bose-Einstein condensate.

    PubMed

    Lahav, Oren; Itah, Amir; Blumkin, Alex; Gordon, Carmit; Rinott, Shahar; Zayats, Alona; Steinhauer, Jeff

    2010-12-10

    We have created an analog of a black hole in a Bose-Einstein condensate. In this sonic black hole, sound waves, rather than light waves, cannot escape the event horizon. A steplike potential accelerates the flow of the condensate to velocities which cross and exceed the speed of sound by an order of magnitude. The Landau critical velocity is therefore surpassed. The point where the flow velocity equals the speed of sound is the sonic event horizon. The effective gravity is determined from the profiles of the velocity and speed of sound. A simulation finds negative energy excitations, by means of Bragg spectroscopy.

  8. Disorder-Induced Order in Two-Component Bose-Einstein Condensates

    SciTech Connect

    Niederberger, A.; Schulte, T.; Wehr, J.; Lewenstein, M.; Sanchez-Palencia, L.; Sacha, K.

    2008-01-25

    We propose and analyze a general mechanism of disorder-induced order in two-component Bose-Einstein condensates, analogous to corresponding effects established for XY spin models. We show that a random Raman coupling induces a relative phase of {pi}/2 between the two BECs and that the effect is robust. We demonstrate it in one, two, and three dimensions at T=0 and present evidence that it persists at small T>0. Applications to phase control in ultracold spinor condensates are discussed.

  9. Periodic shedding of vortex dipoles from a moving penetrable obstacle in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Kwon, Woo Jin; Seo, Sang Won; Shin, Yong-il

    2015-09-01

    We investigate vortex shedding from a moving penetrable obstacle in a highly oblate Bose-Einstein condensate. The penetrable obstacle is formed by a repulsive Gaussian laser beam that has the potential barrier height lower than the chemical potential of the condensate. The moving obstacle periodically generates vortex dipoles and the vortex shedding frequency fv linearly increases with the obstacle velocity v as fv=a (v -vc) , where vc is a critical velocity. Based on the periodic shedding behavior, we demonstrate deterministic generation of a single vortex dipole by applying a short linear sweep of a laser beam. This method will allow further controlled vortex experiments such as dipole-dipole collisions.

  10. Phase structure of binary Bose-Einstein condensates at finite temperature

    NASA Astrophysics Data System (ADS)

    Tran, Huu Phat; Nguyen, Tuan Anh; Le, Viet Hoa; Dang, Thi Minh Hue

    2016-08-01

    The dynamical stability and its connection with phase structures of binary Bose-Einstein condensates (BECs) are systematically studied within framework of the Gross-Pitaevskii (GP) theory. We find that (a) the dynamical stability is the main factor governing both the symmetry breaking and the formation of various phases associated with the scenarios: symmetry restoration (SR) and inverse symmetry breaking (ISB); (b) the condensation of Bose gases might occur at constant temperature for chemical potentials varying in some definite regions. We suggest how to experimentally observe the foregoing phenomena whose possible existences in nature are theoretically confirmed.

  11. 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.

  12. 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.

  13. 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.

  14. Quantum kinetic theory. VI. The growth of a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Lee, M. D.; Gardiner, C. W.

    2000-09-01

    A detailed analysis of the growth of a Bose-Einstein condensate is given, based on quantum kinetic theory, in which we take account of the evolution of the occupations of lower trap levels, and of the full Bose-Einstein formula for the occupations of higher trap levels, as well as the Bose-stimulated direct transfer of atoms to the condensate level introduced by Gardiner et al. [Phys. Rev. Lett. 79, 1793 (1997); 81, 5266 (1998)]. We find good agreement with experiment at higher temperatures, but at lower temperatures the experimentally observed growth rate is somewhat more rapid. We also confirm the picture of the ``kinetic'' region of evolution, introduced by Kagan, Svistunov, and Shlyapnikov (Zh. Eksp. Teor. Fiz. 101, 528 (1992) [Sov. Phys. JETP 75, 387 (1992)]), for the time up to the initiation of the condensate. The behavior after initiation essentially follows our original growth equation, but with a substantially increased rate coefficient. Our modeling of growth implicitly gives a model of the spatial shape of the density profile of the condensate-vapor system as the condensate grows, and thus provides an alternative to the present phenomenological fitting procedure, based on the sum of a zero-chemical potential vapor and a Thomas-Fermi-shaped condensate. Our method gives substantially different results for condensate numbers and temperatures obtained from phenomenological fits, but fits the published column density data very well.

  15. Impurity Crystal in a Bose-Einstein Condensate

    SciTech Connect

    Roberts, David C.; Rica, Sergio

    2009-01-16

    We investigate the behavior of impurity fields immersed in a larger condensate field in various dimensions. We discuss the localization of a single impurity field within a condensate and note the effects of surface energy. We derive the functional form of the attractive condensate-mediated interaction between two impurities. Generalizing the analysis to N impurity fields, we show that within various parameter regimes a crystal of impurity fields can form spontaneously in the condensate. Finally, the system of condensate and crystallized impurity structure is shown to have nonclassical rotational inertia, which is characteristic of superfluidity; i.e., the system can be seen to exhibit supersolid behavior.

  16. 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.

  17. 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.

  18. 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.

  19. Cavity Exciton-Polaritons, Bose Einstein Condensation and Spin Dynamics

    SciTech Connect

    Malpuech, Guillaume; Solnyshkov, Dmitry; Shelykh, Ivan

    2009-10-07

    An introduction giving elementary properties of cavity exciton-polariton will be given. The condition of occurrence of the polariton lasing effect and of the polariton Bose Eintein condensation will be discussed. The impact of the structural disorder on the superfluid behavior of polariton condensates will be analysed. The spin properties of polariton condensates will be discussed. I will show how the anisotropy of the polariton-polariton interaction leads to the suppression of zeeman splitting for polariton condensates (spin Meissner effects). I will show how the combined impact of disorder and spin Meissner effect can lead to the formation of a new condense phase. I will show how these phenomena can allow for the realization of a polaritonic Datta Das spin transistor.

  20. A cylindrically symmetric magnetic trap for compact Bose-Einstein condensate atom interferometer gyroscopes.

    PubMed

    Horne, R A; Sackett, C A

    2017-01-01

    We present a variant of the time-orbiting potential trap suitable for Bose-Einstein condensate atom interferometers, which provides weak, cylindrically symmetric confinement as well as support for the atoms against gravity. This trapping configuration is well-suited for the implementation of a compact atom interferometer based gyroscope. The trap is made up of six coils, which were produced using photolithographic techniques and take up a modest volume of approximately 1 cubic inch inside a vacuum chamber. The trapping frequencies and thermal characteristics of the trap are presented, showing cylindrical symmetry and scalability of the trapping frequencies from 1 Hz to 8 Hz in the symmetry plane.

  1. 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.

  2. Energies and damping rates of elementary excitations in spin-1 Bose-Einstein-condensed gases

    NASA Astrophysics Data System (ADS)

    Szirmai, Gergely; Szépfalusy, Péter; Kis-Szabó, Krisztián

    2003-08-01

    The finite temperature Green’s function technique is used to calculate the energies and damping rates of the elementary excitations of homogeneous, dilute, spin-1 Bose gases below the Bose-Einstein condensation temperature in both the density and spin channels. For this purpose a self-consistent dynamical Hartree-Fock model is formulated, which takes into account the direct and exchange processes on equal footing by summing up certain classes of Feynman diagrams. The model is shown to satisfy the Goldstone theorem and to exhibit the hybridization of one-particle and collective excitations correctly. The results are applied to gases of 23Na and 87Rb atoms.

  3. Stabilization of Solitons Generated by a Supersonic Flow of Bose-Einstein Condensate Past an Obstacle

    SciTech Connect

    Kamchatnov, A. M.; Pitaevskii, L. P.

    2008-04-25

    The stability of dark solitons generated by supersonic flow of a Bose-Einstein condensate past an obstacle is investigated. It is shown that in the reference frame attached to the obstacle a transition occurs at some critical value of the flow velocity from absolute instability of dark solitons to their convective instability. This leads to the decay of disturbances of solitons at a fixed distance from the obstacle and the formation of effectively stable dark solitons. This phenomenon explains the surprising stability of the flow picture that has been observed in numerical simulations.

  4. 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

  5. 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.

  6. Vortex formation of a Bose-Einstein condensate in a rotating deep optical lattice

    SciTech Connect

    Kato, Akira; Nakano, Yuki; Kasamatsu, Kenichi; Matsui, Tetsuo

    2011-11-15

    We study the dynamics of vortex nucleation and lattice formation in a Bose-Einstein condensate in a rotating square optical lattice by numerical simulations of the Gross-Pitaevskii equation. Different dynamical regimes of vortex nucleation are found, depending on the depth and period of the optical lattice. We make an extensive comparison with the experiments by R. A. Williams et al.[Phys. Rev. Lett. 104, 050404 (2010)], especially focusing on the issues of the critical rotation frequency for the first vortex nucleation and the vortex number as a function of rotation frequency.

  7. Defect modes of a Bose-Einstein condensate in an optical lattice with a localized impurity

    SciTech Connect

    Brazhnyi, Valeriy A.; Konotop, Vladimir V.; Perez-Garcia, Victor M.

    2006-08-15

    We study defect modes of a Bose-Einstein condensate in an optical lattice with a localized defect within the framework of the one-dimensional Gross-Pitaevskii equation. It is shown that for a significant range of parameters the defect modes can be accurately described by an expansion over Wannier functions, whose envelope is governed by the coupled nonlinear Schroedinger equations with a {delta} impurity. The stability of the defect modes is verified by direct numerical simulations of the underlying Gross-Pitaevskii equation with a periodic and defect potentials. We also discuss possibilities of driving defect modes through the lattice and suggest ideas for their experimental generation.

  8. 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.

  9. 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.

  10. 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.

  11. 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}

  12. 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

  13. 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.

  14. 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.

  15. Analysis of dynamical tunneling experiments with a Bose-Einstein condensate

    SciTech Connect

    Hensinger, W.K.; Mouchet, A.; Julienne, P. S.; Delande, D.; Heckenberg, N.R.; Rubinsztein-Dunlop, H.

    2004-07-01

    Dynamical tunneling is a quantum phenomenon where a classically forbidden process occurs that is prohibited not by energy but by another constant of motion. The phenomenon of dynamical tunneling has been recently observed in a sodium Bose-Einstein condensate. We present a detailed analysis of these experiments using numerical solutions of the three-dimensional Gross-Pitaevskii equation and the corresponding Floquet theory. We explore the parameter dependency of the tunneling oscillations and we move the quantum system towards the classical limit in the experimentally accessible regime.

  16. Photon recoil momentum in a Bose-Einstein condensate of a dilute gas

    NASA Astrophysics Data System (ADS)

    Avetisyan, Yu A.; Malyshev, V. A.; Trifonov, E. D.

    2017-04-01

    We develop a ‘minimal’ microscopic model to describe a two-pulse-Ramsey-interferometer-based scheme of measurement of the photon recoil momentum in a Bose-Einstein condensate of a dilute gas (Campbell et al 2005 Phys. Rev. Lett. 94 170403). We exploit the truncated coupled Maxwell-Schrödinger equations to elaborate the problem. Our approach provides a theoretical tool to reproduce essential features of the experimental results. Additionally, we calculate the quantum-mechanical mean value of the recoil momentum and its statistical distribution that provides a detailed information about the recoil event.

  17. Einstein-Podolsky-Rosen Correlations via Dissociation of a Molecular Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Kheruntsyan, K. V.; Olsen, M. K.; Drummond, P. D.

    2005-10-01

    Recent experimental measurements of atomic intensity correlations through atom shot noise suggest that atomic quadrature phase correlations may soon be measured with a similar precision. We propose a test of local realism with mesoscopic numbers of massive particles based on such measurements. Using dissociation of a Bose-Einstein condensate of diatomic molecules into bosonic atoms, we demonstrate that strongly entangled atomic beams may be produced which possess Einstein-Podolsky-Rosen (EPR) correlations in field quadratures in direct analogy to the position and momentum correlations originally considered by EPR.

  18. Slow light in a cavity optomechanical system with a Bose-Einstein condensate

    SciTech Connect

    Chen Bin; Jiang Cheng; Zhu Kadi

    2011-05-15

    We theoretically investigate the light propagation in a cavity optomechanical system with a Bose-Einstein condensate (BEC). It is shown that slow light can easily be realized in this system via a BEC coupled to an optical cavity field. The numerical results further demonstrate that the transmitted probe beam from the cavity can be delayed as much as 0.8 ms by suitably selecting the pump field detuning from the cavity field frequency. The scheme proposed here may have potential applications in telecommunication and interferometry.

  19. Bose-Einstein condensation of {alpha} particles and Airy structure in nuclear rainbow scattering

    SciTech Connect

    Ohkubo, S.; Hirabayashi, Y.

    2004-10-01

    It is shown that the dilute density distribution of {alpha} particles in nuclei can be observed in the Airy structure in nuclear rainbow scattering. We have analyzed {alpha}+{sup 12}C rainbow scattering to the 0{sub 2}{sup +} (7.65 MeV) state of {sup 12}C in a coupled-channel method with the precise wave functions for {sup 12}C. It is found that the enhanced Airy oscillations in the experimental angular distributions for the 0{sub 2}{sup +} state is caused by the dilute density distribution of this state in agreement for the idea of Bose-Einstein condensation of the three alpha particles.

  20. Solitary waves of Bose-Einstein-condensed atoms confined in finite rings

    SciTech Connect

    Smyrnakis, J.; Magiropoulos, M.; Kavoulakis, G. M.; Jackson, A. D.

    2010-08-15

    Motivated by recent progress in trapping Bose-Einstein-condensed atoms in toroidal potentials, we examine solitary-wave solutions of the nonlinear Schroedinger equation subject to periodic boundary conditions. When the circumference of the ring is much larger than the size of the wave, the density profile is well approximated by that of an infinite ring; however, the density and the velocity of propagation cannot vanish simultaneously. When the size of the ring becomes comparable to the size of the wave, the density variation becomes sinusoidal and the velocity of propagation saturates to a constant value.

  1. Full-time dynamics of modulational instability in spinor Bose-Einstein condensates

    SciTech Connect

    Doktorov, Evgeny V.; Rothos, Vassilis M.; Kivshar, Yuri S.

    2007-07-15

    We describe the full-time dynamics of modulational instability in F=1 spinor Bose-Einstein condensates for the case of the integrable three-component model associated with the matrix nonlinear Schroedinger equation. We obtain an exact homoclinic solution of this model by employing the dressing method which we generalize to the case of the higher-rank projectors. This homoclinic solution describes the development of modulational instability beyond the linear regime, and we show that the modulational instability demonstrates the reversal property when the growth of the modulated amplitude is changed by its exponential decay.

  2. Tunneling in the self-trapped regime of a two-well Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Pudlik, Tadeusz; Hennig, Holger; Witthaut, Dirk; Campbell, David K.

    2014-11-01

    Starting from a mean-field model of the Bose-Einstein condensate dimer, we reintroduce classically forbidden tunneling through a Bohr-Sommerfeld quantization approach. We find closed-form approximations to the tunneling frequency more accurate than those previously obtained using different techniques. We discuss the central role that tunneling in the self-trapped regime plays in a quantitatively accurate model of a dissipative dimer leaking atoms to the environment. Finally, we describe the prospects of experimental observation of tunneling in the self-trapped regime, both with and without dissipation.

  3. Excitations from a Bose-Einstein condensate of magnons in coupled spin ladders.

    PubMed

    Garlea, V O; Zheludev, A; Masuda, T; Manaka, H; Regnault, L-P; Ressouche, E; Grenier, B; Chung, J-H; Qiu, Y; Habicht, K; Kiefer, K; Boehm, M

    2007-04-20

    The weakly coupled quasi-one-dimensional spin ladder compound (CH3)2CHNH3CuCl3 is studied by neutron scattering in magnetic fields exceeding the critical field of Bose-Einstein condensation of magnons. Commensurate long-range order and the associated Goldstone mode are detected and found to be similar to those in reference to spin-dimer materials. However, for the upper two massive magnon branches, the observed behavior is totally different, culminating in a drastic collapse of excitation bandwidth beyond the transition point.

  4. Excitations from a Bose-Einstein Condensate of Magnons in Coupled Spin Ladders

    SciTech Connect

    Garlea, Vasile O; Zheludev, Andrey I; Masuda, T.; Manaka, H.; Regnault, L.-P.; Ressouche, E.; Grenier, B.; Chung, J.-H.; Qiu, Y.; Habicht, Klaus; Kiefer, K.; Boehm, Martin

    2007-01-01

    The weakly coupled quasi-one-dimensional spin ladder compound CH32HHNH3CuCl3 is studied by neutron scattering in magnetic fields exceeding the critical field of Bose-Einstein condensation of magnons. Commensurate long-range order and the associated Goldstone mode are detected and found to be similar to those in reference to spin-dimer materials. However, for the upper two massive magnon branches, the observed behavior is totally different, culminating in a drastic collapse of excitation bandwidth beyond the transition point.

  5. Decoherence of a quantum harmonic oscillator monitored by a Bose-Einstein condensate

    SciTech Connect

    Brouard, S.; Alonso, D.; Sokolovski, D.

    2011-07-15

    We investigate the dynamics of a quantum oscillator, whose evolution is monitored by a Bose-Einstein condensate (BEC) trapped in a symmetric double-well potential. It is demonstrated that the oscillator may experience various degrees of decoherence depending on the variable being measured and the state in which the BEC is prepared. These range from a ''coherent'' regime in which only the variances of the oscillator position and momentum are affected by measurement, to a slow (power-law) or rapid (Gaussian) decoherence of the mean values themselves.

  6. Effect of scattering lengths on the dynamics of a two-component Bose-Einstein condensate

    SciTech Connect

    Csire, Gabor; Apagyi, Barnabas

    2010-12-15

    We examine the effect of the intra- and interspecies scattering lengths on the dynamics of a two-component Bose-Einstein condensate, particularly focusing on the existence and stability of solitonic excitations. For each type of possible soliton pairs, stability ranges are presented in tabulated form. We also compare the numerically established stability of bright-bright, bright-dark, and dark-dark solitons with our analytical prediction and with that of Painleve analysis of the dynamical equation. We demonstrate that tuning the interspecies scattering length away from the predicted value (keeping the intraspecies coupling fixed) breaks the stability of the soliton pairs.

  7. 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.

  8. 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.

  9. 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.

  10. Bose-Einstein condensate collapse: A comparison between theory and experiment

    SciTech Connect

    Savage, C.M.; Robins, N.P.; Hope, J.J.

    2003-01-01

    We solve the Gross-Pitaevskii equation numerically for the collapse induced by a switch from positive to negative scattering lengths. We compare our results with experiments performed with Bose-Einstein condensates of {sup 85}Rb, in which the scattering length was controlled using a Feshbach resonance. Building on previous theoretical work we identify quantitative differences between the predictions of mean-field theory and the results of the experiments. In addition to the previously reported difference between the predicted and observed critical atom number for collapse, we also find that the predicted collapse times systematically exceed those observed experimentally.

  11. Creation and Detection of Skyrmions in a Bose-Einstein Condensate

    SciTech Connect

    Leslie, L. S.; Deutsch, B. M.; Hansen, A.; Wright, K. C.; Bigelow, N. P.

    2009-12-18

    We present the first experimental realization and characterization of two-dimensional Skyrmions and half-Skyrmions in a spin-2 Bose-Einstein condensate. The continuous rotation of the local spin of the Skyrmion through an angle of pi (and half-Skyrmion through an angle of pi/2) across the cloud is confirmed by the spatial distribution of the three spin states as parametrized by the bending angle of the l vector. The winding number w=(0,1,2) of the internal spin states comprising the Skyrmions is confirmed through matter-wave interference.

  12. 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.

  13. A hybrid two-component Bose-Einstein condensate interferometer for measuring magnetic field gradients

    NASA Astrophysics Data System (ADS)

    Xu, Fei; Huang, Jiahao; Liu, Quan

    2017-03-01

    We have proposed a scheme to detect magnetic field gradients via an interferometer based on a double-well two-component Bose-Einstein condensate (BEC). Utilizing a sequence of quantum control operations on both external and internal degree of the BEC, one can extract the magnetic field gradients by measuring either the population in one component or the fidelity between the final external state and the initial ground state. Our scheme can be implemented by current experimental techniques of manipulating ultracold atoms.

  14. Low-Acceleration Instability of a Bose-Einstein Condensate in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Kos̆Trun, Marijan; Javanainen, Juha

    2004-11-01

    We study a Bose-Einstein condensate in a one-dimensional accelerated optical lattice using the mean-field version of the Bose-Hubbard model. Reminiscent of recent experiments [

    M. Cristiani et al., Opt. Express 12, 4 (2004)OPEXFF1094-408710.1364/OPEX.12.000004
    ], we find a new type of an instability in this system that occurs in the limit when the acceleration is small.

  15. 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.

  16. Manipulation of collective quantum states in Bose-Einstein condensates by continuous imaging

    NASA Astrophysics Data System (ADS)

    Wade, Andrew C. J.; Sherson, Jacob F.; Mølmer, Klaus

    2016-02-01

    We develop a Gaussian state treatment that allows a transparent quantum description of the continuous, nondestructive imaging of and feedback on a Bose-Einstein condensate. We have previously demonstrated [A. C. J. Wade et al., Phys. Rev. Lett. 115, 060401 (2015), 10.1103/PhysRevLett.115.060401] that the measurement backaction of stroboscopic imaging leads to selective squeezing and entanglement of quantized density oscillations. Here, we investigate how the squeezing and entanglement are affected by the finite spatial resolution and geometry of the probe laser beam and of the detector and how they can be optimized.

  17. Nonlinear localized eigenmodes for a Bose-Einstein condensate in a double-well potential

    NASA Astrophysics Data System (ADS)

    Xie, Qiongtao; Liu, Xiaoliang; Rong, Shiguang

    2015-09-01

    In this paper, we investigate the nonlinear localized eigenmodes for a Bose-Einstein condensate in a double-well potential. For a specific choice of the potential parameters, certain exact analytical solutions for nonlinear localized eigenmodes are presented. By applying the linear stability analysis, the stability regions of these exact nonlinear localized eigenmodes are obtained numerically. It is shown that under certain conditions, the unstable nonlinear localized modes display the breathing behavior characterized by repeated appearance of symmetric and asymmetric distributions in the two potentials. This breathing behavior is shown to arise from the symmetry breaking for these nonlinear localized eigenmodes.

  18. Observation of Spontaneous Coherence in Bose-Einstein Condensate of Magnons

    SciTech Connect

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

    2008-02-01

    The room-temperature dynamics of a magnon gas driven by short microwave pumping pulses is studied. An overpopulation of the lowest energy level of the system following the pumping is observed. Using the sensitivity of the Brillouin light scattering technique to the coherence degree of the scattering magnons we demonstrate the spontaneous emergence of coherence of the magnons at the lowest level, if their density exceeds a critical value. This finding is clear proof of the quantum nature of the observed phenomenon and direct evidence of Bose-Einstein condensation of magnons at room temperature.

  19. 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.

  20. Very Cold Indeed: The Nanokelvin Physics of Bose-Einstein Condensation

    PubMed Central

    Cornell, Eric

    1996-01-01

    As atoms get colder, they start to behave more like waves and less like particles. Cool a cloud of identical atoms so cold that the wave of each atom starts to overlap with the wave of its neighbor atom, and all of a sudden you wind up with a sort of quantum identity crisis known as Bose-Einstein condensation. How do we get something that cold? And what is the nature of the strange goop that results? These questions were addressed in a colloquium at the National Institute of Standards and Technology in Gaithersburg, Maryland, on February 23, 1996. This paper is an edited transcript of that presentation. PMID:27805098

  1. Quantum Kibble-Zurek Mechanism in a Spin-1 Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Anquez, M.; Robbins, B. A.; Bharath, H. M.; Boguslawski, M.; Hoang, T. M.; Chapman, M. S.

    2016-04-01

    The dynamics of a quantum phase transition are explored using slow quenches from the polar to the broken-axisymmetry phases in a small spin-1 ferromagnetic Bose-Einstein condensate. Measurements of the evolution of the spin populations reveal a power-law scaling of the temporal onset of excitations versus quench speed as predicted from quantum extensions of the Kibble-Zurek mechanism. The satisfactory agreement of the measured scaling exponent with the analytical theory and numerical simulations provides experimental confirmation of the quantum Kibble-Zurek model.

  2. 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.

  3. Nonlinear resonant tunneling of Bose-Einstein condensates in tilted optical lattices

    SciTech Connect

    Rapedius, K.; Elsen, C.; Korsch, H. J.; Witthaut, D.; Wimberger, S.

    2010-12-15

    We study the tunneling decay of a Bose-Einstein condensate from tilted optical lattices within the mean-field approximation. We introduce a method to calculate ground and excited resonance eigenstates of the Gross-Pitaevskii equation, based on a grid relaxation procedure with complex absorbing potentials. This algorithm works efficiently in a wide range of parameters where established methods fail. It allows us to study the effects of the nonlinearity in detail in the regime of resonant tunneling, where the decay rate is enhanced by resonant coupling to excited unstable states.

  4. 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.

  5. Splitting Times of Doubly Quantized Vortices in Dilute Bose-Einstein Condensates

    SciTech Connect

    Huhtamaeki, J. A. M.; Pietilae, V.; Virtanen, S. M. M.; Moettoenen, M.; Isoshima, T.

    2006-09-15

    Recently, the splitting of a topologically created doubly quantized vortex into two singly quantized vortices was experimentally investigated in dilute atomic cigar-shaped Bose-Einstein condensates [Y. Shin et al., Phys. Rev. Lett. 93, 160406 (2004)]. In particular, the dependency of the splitting time on the peak particle density was studied. We present results of theoretical simulations which closely mimic the experimental setup. We show that the combination of gravitational sag and time dependency of the trapping potential alone suffices to split the doubly quantized vortex in time scales which are in good agreement with the experiments.

  6. 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.}

  7. 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.

  8. Cooperative ring exchange and quantum melting of vortex lattices in atomic Bose-Einstein condensates

    SciTech Connect

    Ghosh, Tarun Kanti; Baskaran, G.

    2004-02-01

    Cooperative ring exchange is suggested as a mechanism of quantum melting of vortex lattices in a rapidly rotating quasi-two-dimensional atomic Bose-Einstein condensate (BEC). Using an approach pioneered by Kivelson et al. [Phys. Rev. Lett. 56, 873 (1986)] for the fractional quantized Hall effect, we calculate the condition for quantum melting instability by considering large-correlated ring exchanges in a two-dimensional Wigner crystal of vortices in a strong 'pseudomagnetic field' generated by the background superfluid Bose particles. BEC may be profitably used to address issues of quantum melting of a pristine Wigner solid devoid of complications of real solids.

  9. Guiding-center dynamics of vortex dipoles in Bose-Einstein condensates

    SciTech Connect

    Middelkamp, S.; Schmelcher, P.; Torres, P. J.; Kevrekidis, P. G.; Frantzeskakis, D. J.; Carretero-Gonzalez, R.; Freilich, D. V.; Hall, D. S.

    2011-07-15

    A quantized vortex dipole is the simplest vortex molecule, comprising two countercirculating vortex lines in a superfluid. Although vortex dipoles are endemic in two-dimensional superfluids, the precise details of their dynamics have remained largely unexplored. We present here several striking observations of vortex dipoles in dilute-gas Bose-Einstein condensates, and develop a vortex-particle model that generates vortex line trajectories that are in good agreement with the experimental data. Interestingly, these diverse trajectories exhibit essentially identical quasiperiodic behavior, in which the vortex lines undergo stable epicyclic orbits.

  10. 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.

  11. 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.

  12. Vortex entanglement in Bose-Einstein condensates coupled to Laguerre-Gauss beams

    SciTech Connect

    Lo Gullo, N.; McEndoo, S.; Busch, T.; Paternostro, M.

    2010-05-15

    We study the establishment of vortex entanglement in remote Bose-Einstein condensates (BECs). We consider a two-mode photonic resource entangled in its orbital angular momentum (OAM) degree of freedom and, by exploiting the process of light-to-BEC OAM transfer, demonstrate that such entanglement can be efficiently passed to the matterlike systems. Our proposal thus represents a building block for novel dissipation-free and long-memory communication channels based on OAM. We discuss issues of practical realizability, stressing the feasibility of our scheme, and present an operative technique for the indirect inference of the set vortex entanglement.

  13. 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.

  14. Diffraction of a Bose-Einstein condensate in the time domain

    SciTech Connect

    Colombe, Yves; Mercier, Brigitte; Perrin, Helene; Lorent, Vincent

    2005-12-15

    We have observed the diffraction of a Bose-Einstein condensate of rubidium atoms on a vibrating mirror potential. The matter wave packet bounces back at normal incidence on a blue-detuned evanescent light field after a 3.6 mm free fall. The mirror vibrates at a frequency of 500 kHz with an amplitude of 3 nm. The atomic carrier and side bands are directly imaged during their ballistic expansion. The locations and the relative weights of the diffracted atomic wave packets are in very good agreement with the theoretical prediction of Henkel et al. [J. Phys. II 4, 1877 (1994)].

  15. Einstein-Podolsky-Rosen Correlations via Dissociation of a Molecular Bose-Einstein Condensate

    SciTech Connect

    Kheruntsyan, K.V.; Drummond, P.D.; Olsen, M.K.

    2005-10-07

    Recent experimental measurements of atomic intensity correlations through atom shot noise suggest that atomic quadrature phase correlations may soon be measured with a similar precision. We propose a test of local realism with mesoscopic numbers of massive particles based on such measurements. Using dissociation of a Bose-Einstein condensate of diatomic molecules into bosonic atoms, we demonstrate that strongly entangled atomic beams may be produced which possess Einstein-Podolsky-Rosen (EPR) correlations in field quadratures in direct analogy to the position and momentum correlations originally considered by EPR.

  16. Controlling phase separation of binary Bose-Einstein condensates via mixed-spin-channel Feshbach resonance

    SciTech Connect

    Tojo, Satoshi; Taguchi, Yoshihisa; Masuyama, Yuta; Hayashi, Taro; Hirano, Takuya; Saito, Hiroki

    2010-09-15

    We investigate controlled phase separation of a binary Bose-Einstein condensate in the proximity of a mixed-spin-channel Feshbach resonance in the |F=1,m{sub F}=+1> and |F=2,m{sub F}=-1> states of {sup 87}Rb at a magnetic field of 9.10 G. Phase separation occurs on the lower-magnetic-field side of the Feshbach resonance while the two components overlap on the higher-magnetic-field side. The Feshbach resonance curve of the scattering length is obtained from the shape of the atomic cloud by comparison with the numerical analysis of coupled Gross-Pitaevskii equations.

  17. Finite-size effects in Anderson localization of one-dimensional Bose-Einstein condensates

    SciTech Connect

    Cestari, J. C. C.; Foerster, A.; Gusmao, M. A.

    2010-12-15

    We investigate the disorder-induced localization transition in Bose-Einstein condensates for the Anderson and Aubry-Andre models in the noninteracting limit using exact diagonalization. We show that, in addition to the standard superfluid fraction, other tools such as the entanglement and fidelity can provide clear signatures of the transition. Interestingly, the fidelity exhibits good sensitivity even for small lattices. Effects of the system size on these quantities are analyzed in detail, including the determination of a finite-size-scaling law for the critical disorder strength in the case of the Anderson model.

  18. 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.

  19. Bose-Einstein Condensation in a Dilute Gas; the First 70 Years and Some Recent Experiments

    NASA Astrophysics Data System (ADS)

    Cornell, E. A.; Wieman, C. E.

    Bose-Einstein condensation, or BEC, has a long and rich history dating from the early 1920s. In this article we will trace briefly over this history and some of the developments in physics that made possible our successful pursuit of BEC in a gas. We will then discuss what was involved in this quest. In this discussion we will go beyond the usual technical description to try and address certain questions that we now hear frequently, but are not covered in our past research papers. These are questions along the lines of ``How did you get the idea and decide to pursue it? Did you know it was going to work? How long did it take you and why?'' We will review some of our favorites from among the experiments we have carried out with BEC. There will then be a brief encore on why we are optimistic that BEC can be created with nearly any species of magnetically trappable atom. Throughout this article we will try to explain what makes BEC in a dilute gas so interesting, unique, and experimentally challenging. This article is our ``Nobel Lecture'' and as such takes a relatively personal approach to the story of the development of experimental Bose-Einstein condensation. For a somewhat more scholarly treatment of the history, the interested reader is referred to E. A. Cornell, J. R. Ensher and C. E. Wieman, ``Experiments in dilute atomic Bose-Einstein condensation in Bose-Einstein Condensation in Atomic Gases, Proceedings of the International School of Physics ``Enrico Fermi'' Course CXL'' (M. Inguscio, S. Stringari and C. E. Wieman, Eds., Italian Physical Society, 1999), pp. 15-66, which is also available as cond-mat/9903109. For a reasonably complete technical review of the three years of explosive progress that immediately followed the first observation of BEC, we recommend reading the above article in combination with the corresponding review from Ketterle, cond-mat/9904034.

  20. Theory of microwave superradiance from a Bose-Einstein condensate of magnons

    SciTech Connect

    Rezende, Sergio M.

    2009-02-01

    We show that the nearly uniform mode generated by the confluence of Bose-Einstein condensate (BEC) magnon pairs produced by microwave radiation in a film of yttrium iron garnet (YIG) is a coherent magnon state. This state corresponds to a macroscopic precessing magnetization which emits a superradiant microwave signal as a result of the cooperative action of the spins. The theory explains quantitatively recent experimental observations of microwave emission from a BEC of magnons in a YIG film when the driving power exceeds a critical value.

  1. 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.

  2. Stability of the graviton Bose-Einstein condensate in the brane-world

    NASA Astrophysics Data System (ADS)

    Casadio, Roberto; da Rocha, Roldão

    2016-12-01

    We consider a solution of the effective four-dimensional Einstein equations, obtained from the general relativistic Schwarzschild metric through the principle of Minimal Geometric Deformation (MGD). Since the brane tension can, in general, introduce new singularities on a relativistic Eötvös brane model in the MGD framework, we require the absence of observed singularities, in order to constrain the brane tension. We then study the corresponding Bose-Einstein condensate (BEC) gravitational system and determine the critical stability region of BEC MGD stellar configurations. Finally, the critical stellar densities are shown to be related with critical points of the information entropy.

  3. Measurement of collective excitations in a spin-orbit-coupled Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Khamehchi, M. A.; Zhang, Yongping; Hamner, Chris; Busch, Thomas; Engels, Peter

    2014-12-01

    We measure the collective excitation spectrum of a spin-orbit-coupled Bose-Einstein condensate using Bragg spectroscopy. The spin-orbit coupling is generated by Raman dressing of atomic hyperfine states. When the Raman detuning is reduced, mode softening at a finite momentum is revealed, which provides insight into a supersolid-like phase transition. We find that for the parameters of our system, this softening stops at a finite excitation gap and is symmetric under a sign change of the Raman detuning. Finally, using a moving barrier that is swept through the BEC, we also show the effect of the collective excitation on the fluid dynamics.

  4. Bright solitons in spin-orbit-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Xu, Yong; Zhang, Yongping; Wu, Biao

    2013-01-01

    We study bright solitons in a Bose-Einstein condensate with a spin-orbit coupling that has been realized experimentally. Both stationary bright solitons and moving bright solitons are found. The stationary bright solitons are the ground states and possess well-defined spin-parity, a symmetry involving both spatial and spin degrees of freedom; these solitons are real valued but not positive definite, and the number of their nodes depends on the strength of spin-orbit coupling. For the moving bright solitons, their shapes are found to change with velocity due to the lack of Galilean invariance in the system.

  5. 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.

  6. Excitonic Bose-Einstein condensation in Ta2NiSe5 above room temperature

    NASA Astrophysics Data System (ADS)

    Seki, K.; Wakisaka, Y.; Kaneko, T.; Toriyama, T.; Konishi, T.; Sudayama, T.; Saini, N. L.; Arita, M.; Namatame, H.; Taniguchi, M.; Katayama, N.; Nohara, M.; Takagi, H.; Mizokawa, T.; Ohta, Y.

    2014-10-01

    We show that finite temperature variational cluster approximation (VCA) calculations on an extended Falicov-Kimball model can reproduce angle-resolved photoemission spectroscopy (ARPES) results on Ta2NiSe5 across a semiconductor-to-semiconductor structural phase transition at 325 K. We demonstrate that the characteristic temperature dependence of the flat-top valence band observed by ARPES is reproduced by the VCA calculation on the realistic model for an excitonic insulator only when the strong excitonic fluctuation is taken into account. The present calculations indicate that Ta2NiSe5 falls in the Bose-Einstein condensation regime of the excitonic insulator state.

  7. All-optical transistor based on a cavity optomechanical system with a Bose-Einstein condensate

    SciTech Connect

    Chen, Bin; Jiang, Cheng; Li, Jin-Jin; Zhu, Ka-Di

    2011-11-15

    We propose a scheme of an all-optical transistor based on a coupled Bose-Einstein condensate cavity system. The calculated results show that, in such an optomechanical system, the transmission of the probe beam is strongly dependent on the optical pump power. Therefore, the optical pump field can serve as a ''gate'' field of the transistor, effectively controlling the propagation of the probe field (the ''signal'' field). The scheme proposed here may have potential applications in optical communication and quantum information processing.

  8. Chaos enhancing tunneling in a coupled Bose-Einstein condensate with a double driving.

    PubMed

    Rong, Shiguang; Hai, Wenhua; Xie, Qiongtao; Zhu, Qianquan

    2009-09-01

    We study the effects of chaotic dynamics on atomic tunneling between two weakly coupled Bose-Einstein condensates driven by a double-frequency periodic field. Under the Melnikov's chaos criterion, we divide the parameter space into three parts of different types, regular region, low-chaoticity region, and high-chaoticity region, and give the accurate boundaries between the different regions. It is found that the atomic tunneling can be enhanced in the presence of chaos. Particularly, in the high-chaoticity regions, the chaos-induced inversion of the population imbalance is observed numerically.

  9. Dynamics of bubbles in a two-component Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Sasaki, Kazuki; Suzuki, Naoya; Saito, Hiroki

    2011-03-01

    The dynamics of a phase-separated two-component Bose-Einstein condensate are investigated, in which a bubble of one component moves through the other component. Numerical simulations of the Gross-Pitaevskii equation reveal a variety of dynamics associated with the creation of quantized vortices. In two dimensions, a circular bubble deforms into an ellipse and splits into fragments with vortices, which undergo the Magnus effect. The Bénard-von Kármán vortex street is also generated. In three dimensions, a spherical bubble deforms into toruses with vortex rings. When two rings are formed, they exhibit leapfrogging dynamics.

  10. Dynamics of bubbles in a two-component Bose-Einstein condensate

    SciTech Connect

    Sasaki, Kazuki; Suzuki, Naoya; Saito, Hiroki

    2011-03-15

    The dynamics of a phase-separated two-component Bose-Einstein condensate are investigated, in which a bubble of one component moves through the other component. Numerical simulations of the Gross-Pitaevskii equation reveal a variety of dynamics associated with the creation of quantized vortices. In two dimensions, a circular bubble deforms into an ellipse and splits into fragments with vortices, which undergo the Magnus effect. The Benard-von Karman vortex street is also generated. In three dimensions, a spherical bubble deforms into toruses with vortex rings. When two rings are formed, they exhibit leapfrogging dynamics.

  11. Moving obstacle potential in a spin-orbit-coupled Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

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

    2017-09-01

    We investigate the dynamics around an obstacle potential moving in the plane-wave state of a pseudospin-1 /2 Bose-Einstein condensate with Rashba spin-orbit coupling. We numerically investigate the dynamics of the system and find that it depends not only on the velocity of the obstacle but also significantly on the direction of obstacle motion, both of which are verified by the Bogoliubov analysis. The excitation diagram with respect to the velocity and direction is obtained. The dependence of the critical velocity on the strength of the spin-orbit coupling and the size of the obstacle is also investigated.

  12. High-fidelity manipulation of a Bose-Einstein condensate using an optical standing wave

    SciTech Connect

    Hughes, K. J.; Deissler, B.; Burke, J. H. T.; Sackett, C. A.

    2007-09-15

    The use of off-resonant standing light waves to manipulate ultracold atoms is investigated. Previous work has illustrated that Bragg diffraction can provide efficient beam-splitting and reflection operations for atomic wave packets. The performance of these operations is characterized experimentally using Bose-Einstein condensates confined in a weak magnetic trap. Fidelities of 0.99 for beam splitting and 0.98 for reflection are observed, and splitting operations of up to third order are achieved. The dependence of the operations on light intensity and atomic velocity is measured and found to agree well with theoretical estimates.

  13. 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.

  14. Superfluidity of a nonequilibrium Bose-Einstein condensate of polaritons

    SciTech Connect

    Wouters, Michiel; Savona, Vincenzo

    2010-02-01

    We study theoretically superfluidity in a driven-dissipative Bose gas out of thermal equilibrium, and discuss the relation with conventional superfluids. We show how the superfluid behavior is characterized by a dramatic increase in the lifetime of a quantized vortex and point out the influence of the spatial geometry of the condensate. We apply our study to a condensate of polaritons in a semiconductor microcavity, whose properties can be directly inferred from optical spectroscopy. We propose three different experimental schemes to measure the vorticity of the polariton condensate.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  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. Dynamics of Spin-Orbit Coupled Bose-Einstein Condensates in a Random Potential

    NASA Astrophysics Data System (ADS)

    Mardonov, Sh.; Modugno, M.; Sherman, E. Ya.

    2015-10-01

    Disorder plays a crucial role in spin dynamics in solids and condensed matter systems. We demonstrate that for a spin-orbit coupled Bose-Einstein condensate in a random potential two mechanisms of spin evolution that can be characterized as "precessional" and "anomalous" are at work simultaneously. The precessional mechanism, typical for solids, is due to the condensate displacement. The unconventional anomalous mechanism is due to the spin-dependent velocity producing the distribution of the condensate spin polarization. The condensate expansion is accompanied by a random displacement and fragmentation, where it becomes sparse, as clearly revealed in the spin dynamics. Thus, different stages of the evolution can be characterized by looking at the condensate spin.

  2. Stepwise Bose-Einstein Condensation in a Spinor Gas

    NASA Astrophysics Data System (ADS)

    Frapolli, C.; Zibold, T.; Invernizzi, A.; Jiménez-García, K.; Dalibard, J.; Gerbier, F.

    2017-08-01

    We observe multistep condensation of sodium atoms with spin F =1 , where the different Zeeman components mF=0 ,±1 condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the magnetization mz and on the quadratic Zeeman energy q (QZE) in an applied magnetic field. For large QZE, the overall structure of the phase diagram is the same as for an ideal spin-1 gas, although the precise locations of the phase boundaries are significantly shifted by interactions. For small QZE, antiferromagnetic interactions qualitatively change the phase diagram with respect to the ideal case, leading, for instance, to condensation in mF=±1 , a phenomenon that cannot occur for an ideal gas with q >0 .

  3. Stepwise Bose-Einstein Condensation in a Spinor Gas.

    PubMed

    Frapolli, C; Zibold, T; Invernizzi, A; Jiménez-García, K; Dalibard, J; Gerbier, F

    2017-08-04

    We observe multistep condensation of sodium atoms with spin F=1, where the different Zeeman components m_{F}=0,±1 condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the magnetization m_{z} and on the quadratic Zeeman energy q (QZE) in an applied magnetic field. For large QZE, the overall structure of the phase diagram is the same as for an ideal spin-1 gas, although the precise locations of the phase boundaries are significantly shifted by interactions. For small QZE, antiferromagnetic interactions qualitatively change the phase diagram with respect to the ideal case, leading, for instance, to condensation in m_{F}=±1, a phenomenon that cannot occur for an ideal gas with q>0.

  4. Finite-temperature vortex dynamics in Bose-Einstein condensates

    SciTech Connect

    Jackson, B.; Proukakis, N. P.; Barenghi, C. F.; Zaremba, E.

    2009-05-15

    We study the dynamics of a vortex in an atomic Bose-condensed gas at finite temperature within the Zaremba-Nikuni-Griffin formalism. In a harmonically trapped pancake-shaped condensate, an off-centered vortex is known to decay by spiraling out toward the edge of the condensate. We quantify the dependence of this decay on temperature, atomic collisions, and thermal cloud rotation. Near the trap center where the density varies slowly, we show that our numerical results agree with the predictions of the Hall-Vinen phenomenological friction force model used to describe quantized vorticity in superfluid systems. Our result thus clarifies the microscopic origin of the friction and provides an ab initio determination of its value.

  5. Bose-Einstein Condensation and Bose Glasses in an S = 1 Organo-metallic quantum magnet

    SciTech Connect

    Zapf, Vivien

    2012-06-01

    I will speak about Bose-Einstein condensation (BEC) in quantum magnets, in particular the compound NiCl2-4SC(NH2)2. Here a magnetic field-induced quantum phase transition to XY antiferromagnetism can be mapped onto BEC of the spins. The tuning parameter for BEC transition is the magnetic field rather than the temperature. Some interesting phenomena arise, for example the fact that the mass of the bosons that condense can be strongly renormalized by quantum fluctuations. I will discuss the utility of this mapping for both understanding the nature of the quantum magnetism and testing the thermodynamic limit of Bose-Einstein Condensation. Furthermore we can dope the system in a clean and controlled way to create the long sought-after Bose Glass transition, which is the bosonic analogy of Anderson localization. I will present experiments and simulations showing evidence for a new scaling exponent, which finally makes contact between theory and experiments. Thus we take a small step towards the difficult problem of understanding the effect of disorder on bosonic wave functions.

  6. A stripe phase with supersolid properties in spin-orbit-coupled Bose-Einstein condensates.

    PubMed

    Li, Jun-Ru; Lee, Jeongwon; Huang, Wujie; Burchesky, Sean; Shteynas, Boris; Top, Furkan Çağrı; Jamison, Alan O; Ketterle, Wolfgang

    2017-03-01

    Supersolidity combines superfluid flow with long-range spatial periodicity of solids, two properties that are often mutually exclusive. The original discussion of quantum crystals and supersolidity focused on solid (4)He and triggered extensive experimental efforts that, instead of supersolidity, revealed exotic phenomena including quantum plasticity and mass supertransport. The concept of supersolidity was then generalized from quantum crystals to other superfluid systems that break continuous translational symmetry. Bose-Einstein condensates with spin-orbit coupling are predicted to possess a stripe phase with supersolid properties. Despite several recent studies of the miscibility of the spin components of such a condensate, the presence of stripes has not been detected. Here we observe the predicted density modulation of this stripe phase using Bragg reflection (which provides evidence for spontaneous long-range order in one direction) while maintaining a sharp momentum distribution (the hallmark of superfluid Bose-Einstein condensates). Our work thus establishes a system with continuous symmetry-breaking properties, associated collective excitations and superfluid behaviour.

  7. Bose-Einstein condensation in dark power-law laser traps

    SciTech Connect

    Jaouadi, A.; Gaaloul, N.; Viaris de Lesegno, B.; Pruvost, L.; Telmini, M.; Charron, E.

    2010-08-15

    We investigate theoretically an original route to achieve Bose-Einstein condensation using dark power-law laser traps. We propose to create such traps with two crossing blue-detuned Laguerre-Gaussian optical beams. Controlling their azimuthal order l allows for the exploration of a multitude of power-law trapping situations in one, two, and three dimensions, ranging from the usual harmonic trap to an almost square-well potential, in which a quasihomogeneous Bose gas can be formed. The usual cigar-shaped and disk-shaped Bose-Einstein condensates obtained in a 1D or 2D harmonic trap take the generic form of a 'finger' or of a 'hockey puck' in such Laguerre-Gaussian traps. In addition, for a fixed atom number, higher transition temperatures are obtained in such configurations when compared with a harmonic trap of the same volume. This effect, which results in a substantial acceleration of the condensation dynamics, requires a better but still reasonable focusing of the Laguerre-Gaussian beams.

  8. Bose-Einstein condensation in dark power-law laser traps

    NASA Astrophysics Data System (ADS)

    Jaouadi, A.; Gaaloul, N.; Viaris de Lesegno, B.; Telmini, M.; Pruvost, L.; Charron, E.

    2010-08-01

    We investigate theoretically an original route to achieve Bose-Einstein condensation using dark power-law laser traps. We propose to create such traps with two crossing blue-detuned Laguerre-Gaussian optical beams. Controlling their azimuthal order ℓ allows for the exploration of a multitude of power-law trapping situations in one, two, and three dimensions, ranging from the usual harmonic trap to an almost square-well potential, in which a quasihomogeneous Bose gas can be formed. The usual cigar-shaped and disk-shaped Bose-Einstein condensates obtained in a 1D or 2D harmonic trap take the generic form of a “finger” or of a “hockey puck” in such Laguerre-Gaussian traps. In addition, for a fixed atom number, higher transition temperatures are obtained in such configurations when compared with a harmonic trap of the same volume. This effect, which results in a substantial acceleration of the condensation dynamics, requires a better but still reasonable focusing of the Laguerre-Gaussian beams.

  9. Observation of Vortex Nucleation in a Rotating Two-Dimensional Lattice of Bose-Einstein Condensates

    SciTech Connect

    Williams, R. A.; Al-Assam, S.; Foot, C. J.

    2010-02-05

    We report the observation of vortex nucleation in a rotating optical lattice. A {sup 87}Rb Bose-Einstein condensate was loaded into a static two-dimensional lattice and the rotation frequency of the lattice was then increased from zero. We studied how vortex nucleation depended on optical lattice depth and rotation frequency. For deep lattices above the chemical potential of the condensate we observed a linear dependence of the number of vortices created with the rotation frequency, even below the thermodynamic critical frequency required for vortex nucleation. At these lattice depths the system formed an array of Josephson-coupled condensates. The effective magnetic field produced by rotation introduced characteristic relative phases between neighboring condensates, such that vortices were observed upon ramping down the lattice depth and recombining the condensates.

  10. Vortices in a toroidal Bose-Einstein condensate with a rotating weak link

    NASA Astrophysics Data System (ADS)

    Yakimenko, A. I.; Bidasyuk, Y. M.; Weyrauch, M.; Kuriatnikov, Y. I.; Vilchinskii, S. I.

    2015-03-01

    Motivated by a recent experiment [K. C. Wright et al., Phys. Rev. Lett. 110, 025302 (2013), 10.1103/PhysRevLett.110.025302], we investigate deterministic discontinuous jumps between quantized circulation states in a toroidally trapped Bose-Einstein condensate. These phase slips are induced by vortex excitations created by a rotating weak link. We analyze the influence of a localized condensate density depletion and atomic superflows, governed by the rotating barrier, on the energetic and dynamical stability of the vortices in the ring-shaped condensate. We simulate in a three-dimensional dissipative mean-field model the dynamics of the condensate using parameters similar to the experimental conditions. Moreover, we consider the dynamics of the stirred condensate far beyond the experimentally explored region and reveal surprising manifestations of complex vortex dynamics.

  11. Stability and Metastability of Trapless Bose-Einstein Condensates and Quantum Liquids

    NASA Astrophysics Data System (ADS)

    Zloshchastiev, Konstantin G.

    2017-07-01

    Various kinds of Bose-Einstein condensates are considered, which evolve without any geometric constraints or external trap potentials including gravitational. For studies of their collective oscillations and stability, including the metastability and macroscopic tunneling phenomena, both the variational approach and the Vakhitov-Kolokolov (VK) criterion are employed; calculations are done for condensates of an arbitrary spatial dimension. It is determined that that the trapless condensate described by the logarithmic wave equation is essentially stable, regardless of its dimensionality, while the trapless condensates described by wave equations of a polynomial type with respect to the wavefunction, such as the Gross-Pitaevskii (cubic), cubic-quintic, and so on, are at best metastable. This means that trapless "polynomial" condensates are unstable against spontaneous delocalization caused by fluctuations of their width, density and energy, leading to a finite lifetime.

  12. 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.

  13. 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.

  14. 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.

  15. Generalized Mean Fields for Trapped Atomic Bose-Einstein Condensates

    PubMed Central

    Proukakis, N. P.; Burnett, K.

    1996-01-01

    We describe generalized time-dependent mean-field equations for partially condensed samples of trapped and evaporatively cooled atoms. These equations give a way of investigating the various order parameters that may be present as well as the existence of a mean value of the field due to condensed atoms. Our approach provides us with a closed system of self-consistent equations for the order parameters present. The equations we derive are shown to reduce to other treatments in the literature in various limits. We also show how the equation of motion method allows us to construct a formalism that can handle the evolution of these mean fields due to two-loop kinetics. PMID:27805101

  16. Calorimetry of a Bose-Einstein-condensed photon gas.

    PubMed

    Damm, Tobias; Schmitt, Julian; Liang, Qi; Dung, David; Vewinger, Frank; Weitz, Martin; Klaers, Jan

    2016-04-19

    Phase transitions, as the condensation of a gas to a liquid, are often revealed by a discontinuous behaviour of thermodynamic quantities. For liquid helium, for example, a divergence of the specific heat signals the transition from the normal fluid to the superfluid state. Apart from liquid helium, determining the specific heat of a Bose gas has proven to be a challenging task, for example, for ultracold atomic Bose gases. Here we examine the thermodynamic behaviour of a trapped two-dimensional photon gas, a system that allows us to spectroscopically determine the specific heat and the entropy of a nearly ideal Bose gas from the classical high temperature to the Bose-condensed quantum regime. The critical behaviour at the phase transition is clearly revealed by a cusp singularity of the specific heat. Regarded as a test of quantum statistical mechanics, our results demonstrate a quantitative agreement with its predictions at the microscopic level.

  17. Calorimetry of a Bose-Einstein-condensed photon gas

    NASA Astrophysics Data System (ADS)

    Damm, Tobias; Schmitt, Julian; Liang, Qi; Dung, David; Vewinger, Frank; Weitz, Martin; Klaers, Jan

    2016-04-01

    Phase transitions, as the condensation of a gas to a liquid, are often revealed by a discontinuous behaviour of thermodynamic quantities. For liquid helium, for example, a divergence of the specific heat signals the transition from the normal fluid to the superfluid state. Apart from liquid helium, determining the specific heat of a Bose gas has proven to be a challenging task, for example, for ultracold atomic Bose gases. Here we examine the thermodynamic behaviour of a trapped two-dimensional photon gas, a system that allows us to spectroscopically determine the specific heat and the entropy of a nearly ideal Bose gas from the classical high temperature to the Bose-condensed quantum regime. The critical behaviour at the phase transition is clearly revealed by a cusp singularity of the specific heat. Regarded as a test of quantum statistical mechanics, our results demonstrate a quantitative agreement with its predictions at the microscopic level.

  18. Direct Observation of Zitterbewegung in a Bose Einstein Condensate

    DTIC Science & Technology

    2013-07-03

    analogous to the Higgs mechanism where a Higgs condensate (a coherent matter wave) generates mass in the standard model [28].) The zitterbewegung of...directly realize Dirac– boson systems in the laboratory [12, 29], permitting access to new classes of experimental systems. Though BECs near these Dirac...http://www.njp.org/) 10 in an optical lattice, can stably populate these states [34, 35], for example leading to bosonic composite-fermion states [36, 37

  19. Black-hole radiation in Bose-Einstein condensates

    SciTech Connect

    Macher, Jean; Parentani, Renaud

    2009-10-15

    We study the phonon fluxes emitted when the condensate velocity crosses the speed of sound, i.e., in backgrounds which are analogous to that of a black hole. We focus on elongated one-dimensional condensates and on stationary flows. Our theoretical analysis and numerical results are based on the Bogoliubov-de Gennes equation without further approximation. The spectral properties of the fluxes and of the long distance density-density correlations are obtained, both with and without an initial temperature. In realistic conditions, we show that the condensate temperature dominates the fluxes and thus hides the presence of the spontaneous emission (the Hawking effect). We also explain why the temperature amplifies the long distance correlations which are intrinsic to this effect. This confirms that the correlation pattern offers a neat signature of the Hawking effect. Optimal conditions for observing the pattern are discussed, as well as correlation patterns associated with scattering of classical waves. Flows associated with white holes are also considered.

  20. Dynamical and Wave Chaos in the Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Reinhardt, William P.; McKinney, Sarah B.

    2001-10-01

    Within the past five years Albert Einstein's concept of a dilute atomic Bose Condensate has been realized in many experimental laboratories. Temperatures in the nano-Kelvin regime have been achieved using magnetic and optical trapping of laser and evaporatively cooled atoms. At such temperatures the relative de Broglie wavelengths of the gaseous trapped atoms can become long compared to their mean spacing, and through a process of bosonic amplification a "quantum phase transition" takes place involving 103 to 1011 atoms, most of which end up in identical single particle quantum states, whose length scales are determined by the external trap. Rb, Na, Li and atomic H have been trapped at variable densities of the order of 1013/cm3, and in traps of varying geometries. Of these all but Li have an effective repulsive atomic pair interaction, but utilization of molecular Feshbach resonances allows the interactions of other species to be tuned over wide ranges of strengths, including control of the sign of the effective atomic pair interactions. Fully quantum and macroscopic systems at such low densities are a theorist's dream: simple Hartree type mean field theory provides a startlingly accurate description of density profiles, low energy excitation frequencies, and such a description, commonly called the Non-linear Schrödinger Equation (NLSE) or the Gross-Pitaevskii (GP) Equation, will be explored here. The NLSE appropriate for attractive atomic interactions is known to lead to chaotically unstable dynamics, and eventual implosion of the condensate should the local number density exceed a critical value. In this work we illustrate this type of chaotic collapse for attractive condensates, and then explore the types of chaotic dynamics of solitons and vortices, which are the signatures of dynamical non-linearity in the repulsive case. Finally the implications of the symmetry-breaking associated with phase rigidity are explored in model simulations of repulsive

  1. Tunneling Dynamics of a Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Potnis, Shreyas

    The simplicity and versatility of ultra-cold atoms make it an ideal system for studying Quantum Mechanical phenomenon like tunneling. This thesis describes progress towards experimentally measuring the time spent by a tunneling particle in the classically forbidden region. A detailed analysis of the experimental requirements to measure the tunneling time is presented along with the experimental tools developed to meet these requirements. These include a thin 1.3mum optical tunnel barrier, a smooth atomic waveguide, and a Larmor clock to measure the tunneling time. Delta-kick cooling is used to achieve the extremely low temperatures required for the tunneling time experiments. A 2.4x reduction in the atomic velocity spread is demonstrated, reducing the rms velocity spread to 0.46(5)mm/s. This corresponds to cooling to an effective temperature of 2.0(4)nK. The thin optical barrier opens up the possibility to study the decay of quasi-bound condensates via tunneling. We develop a novel trapping configuration for this purpose, in which the barrier acts as one of the walls of the trap. Inter-atomic interactions strongly dictate the escape dynamics of the condensate out of this trap, giving rise to three distinct regimes--- classical over the barrier spilling, quantum tunneling driven by interactions, and decay dominated by background losses. We show that in the tunneling regime, the decay rate depends exponentially with the chemical potential of the condensate. Experimental results show good agreement with numerical solutions of the 3D Gross-Pitaevskii equation.

  2. Stable and unstable vortices in multicomponent bose-einstein condensates

    PubMed

    Garcia-Ripoll; Perez-Garcia

    2000-05-08

    We study the stability and dynamics of vortices in two-species condensates as prepared in the recent JILA experiment [Matthews et al., Phys. Rev. Lett. 83, 2498 (1999)]. We find that of the two possible configurations, in which one species has vorticity m = 1 and the other one has m = 0, only one is linearly stable, which agrees with the experimental results. However, it is found that in the unstable case the vortex is not destroyed by the instability, but may be transferred from one species to the other or display complex spatiotemporal dynamics.

  3. Vortex patterns in a fast rotating Bose-Einstein condensate

    SciTech Connect

    Aftalion, Amandine; Blanc, Xavier; Dalibard, Jean

    2005-02-01

    For a fast rotating condensate in a harmonic trap, we investigate the structure of the vortex lattice using wave functions minimizing the Gross-Pitaevskii energy in the lowest Landau level. We find that the minimizer of the energy in the rotating frame has a distorted vortex lattice for which we plot the typical distribution. We compute analytically the energy of an infinite regular lattice and of a class of distorted lattices. We find the optimal distortion and relate it to the decay of the wave function. Finally, we generalize our method to other trapping potentials.

  4. Spin-orbit-coupled dipolar Bose-Einstein condensates.

    PubMed

    Deng, Y; Cheng, J; Jing, H; Sun, C-P; Yi, S

    2012-03-23

    We propose an experimental scheme to create spin-orbit coupling in spin-3 Cr atoms using Raman processes. By employing the linear Zeeman effect and optical Stark shift, two spin states within the ground electronic manifold are selected, which results in a pseudospin-1/2 model. We further study the ground state structures of a spin-orbit-coupled Cr condensate. We show that, in addition to the stripe structures induced by the spin-orbit coupling, the magnetic dipole-dipole interaction gives rise to the vortex phase, in which a spontaneous spin vortex is formed.

  5. Cold-atom gravimetry with a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Debs, J. E.; Altin, P. A.; Barter, T. H.; Döring, D.; Dennis, G. R.; McDonald, G.; Anderson, R. P.; Close, J. D.; Robins, N. P.

    2011-09-01

    We present a cold-atom gravimeter operating with a sample of Bose-condensed 87Rb atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of (83±6)% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources and observe a reduced visibility of (58±4)% for the thermal source. We suspect the loss in visibility is caused partly by wave-front aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and we present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely falling, coherent atomic sources.

  6. Bose-Einstein condensation in a frustrated triangular optical lattice

    NASA Astrophysics Data System (ADS)

    Janzen, Peter; Huang, Wen-Min; Mathey, L.

    2016-12-01

    The recent experimental condensation of ultracold atoms in a triangular optical lattice with a negative effective tunneling parameter paves the way for the study of frustrated systems in a controlled environment. Here, we explore the critical behavior of the chiral phase transition in such a frustrated lattice in three dimensions. We represent the low-energy action of the lattice system as a two-component Bose gas corresponding to the two minima of the dispersion. The contact repulsion between the bosons separates into intra- and intercomponent interactions, referred to as V0 and V12, respectively. We first employ a Huang-Yang-Luttinger approximation of the free energy. For V12/V0=2 , which corresponds to the bare interaction, this approach suggests a first-order phase transition, at which both the U (1 ) symmetry of condensation and the Z2 symmetry of the emergent chiral order are broken simultaneously. Furthermore, we perform a renormalization-group calculation at one-loop order. We demonstrate that the coupling regime 0 1 we show that V0 flows to a negative value, while V12 increases and remains positive. This results in a breakdown of the effective quartic-field theory due to a cubic anisotropy and, again, suggests a discontinuous phase transition.

  7. Cold-atom gravimetry with a Bose-Einstein condensate

    SciTech Connect

    Debs, J. E.; Altin, P. A.; Barter, T. H.; Doering, D.; Dennis, G. R.; McDonald, G.; Close, J. D.; Robins, N. P.; Anderson, R. P.

    2011-09-15

    We present a cold-atom gravimeter operating with a sample of Bose-condensed {sup 87}Rb atoms. Using a Mach-Zehnder configuration with the two arms separated by a two-photon Bragg transition, we observe interference fringes with a visibility of (83{+-}6)% at T=3 ms. We exploit large momentum transfer (LMT) beam splitting to increase the enclosed space-time area of the interferometer using higher-order Bragg transitions and Bloch oscillations. We also compare fringes from condensed and thermal sources and observe a reduced visibility of (58{+-}4)% for the thermal source. We suspect the loss in visibility is caused partly by wave-front aberrations, to which the thermal source is more susceptible due to its larger transverse momentum spread. Finally, we discuss briefly the potential advantages of using a coherent atomic source for LMT, and we present a simple mean-field model to demonstrate that with currently available experimental parameters, interaction-induced dephasing will not limit the sensitivity of inertial measurements using freely falling, coherent atomic sources.

  8. 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.

  9. Bose-Einstein condensation of magnons pumped by the bulk spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Tserkovnyak, Yaroslav; Bender, Scott A.; Duine, Rembert A.; Flebus, Benedetta

    2016-03-01

    We propose inducing Bose-Einstein condensation of magnons in a magnetic insulator by a heat flow oriented toward its boundary. At a critical heat flux, the oversaturated thermal gas of magnons accumulated at the boundary precipitates the condensate, which then grows gradually as the thermal bias is dialed up further. The thermal magnons thus pumped by the magnonic bulk (spin) Seebeck effect must generally overcome both the local Gilbert damping associated with the coherent magnetic dynamics as well as the radiative spin-wave losses toward the magnetic bulk, in order to achieve the threshold of condensation. We quantitatively estimate the requisite bias in the case of the ferrimagnetic yttrium iron garnet, discuss different physical regimes of condensation, and contrast it with the competing (so-called Doppler-shift) bulk instability.

  10. 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.

  11. 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.

  12. Planck-scale traces from the interference pattern of two Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Castellanos, E.; Rivas, J. I.

    2015-04-01

    We analyze the possible effects arising from the Planck scale regime upon the interference pattern of two noninteracting Bose-Einstein condensates. We start with the analysis of the free expansion of a condensate, and have taken into account the effects produced by a deformed dispersion relation, suggested in several quantum-gravity models. The analysis of the condensate free expansion, in particular, the modified free velocity expansion, suggests in a natural way, a modified uncertainty principle that could lead to new phenomenological implications related to the quantum structure of space-time. Finally, we analyze the corresponding separation between the interference fringes after the two condensates overlap, in order to explore the sensitivity of the system to possible signals caused by the Planck scale regime.

  13. Exploring the quantum-classical transition in an optical Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Zhang, Keye; Meystre, Pierre; Zhang, Weiping

    2014-05-01

    Recent experiments have demonstrated the Bose-Einstein condensation of photons in a dye microcavity. A remarkable feature is that it behaves as a condensate of massive particles essentially at room temperature and is coupled to the heat reservoir that realizes grand-canonical conditions. We analyze theoretically the control of that system by a secondary coherent cavity field that produces an optomechanical-like coupling between the probe and the condensate. We find that the controllable quantum statistics associated with the size of the reservoir allow one to prepare the photon condensate in a variety of nonclassical states, carry out quantum nondemolition measurements of its number fluctuations, and provide an effective tool to explore the physics of the quantum-classical transition regime.

  14. Finite temperature expansion dynamics of Bose-Einstein condensates in ring traps

    NASA Astrophysics Data System (ADS)

    Roy, Arko; Angom, D.

    2017-08-01

    We explore the effects of finite temperature on the dynamics of Bose-Einstein condensates (BECs) after it is released from the confining potential. In addition, we examine the variation in the expansion dynamics of the BECs as the confining potential is transformed from a multiply to a simply connected geometry. To include the effects of finite temperatures we use the frozen thermal cloud approximation, and observe unique features of the condensate density distribution when released from the confining potential. We find that at T ≠ 0, during the initial stages of expansion, the multiply connected condensate has more pronounced interference rings compared to the case of zero temperature. Such difference in the dynamical evolution is also evident for simply connected condensates.

  15. 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.

  16. 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.

  17. 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.

  18. Supercurrent in a room-temperature Bose-Einstein magnon condensate

    NASA Astrophysics Data System (ADS)

    Bozhko, Dmytro A.; Serga, Alexander A.; Clausen, Peter; Vasyuchka, Vitaliy I.; Heussner, Frank; Melkov, Gennadii A.; Pomyalov, Anna; L'Vov, Victor S.; Hillebrands, Burkard

    2016-11-01

    A supercurrent is a macroscopic effect of a phase-induced collective motion of a quantum condensate. So far, experimentally observed supercurrent phenomena such as superconductivity and superfluidity have been restricted to cryogenic temperatures. Here, we report on the discovery of a supercurrent in a Bose-Einstein magnon condensate prepared in a room-temperature ferrimagnetic film. The magnon condensate is formed in a parametrically pumped magnon gas and is subject to a thermal gradient created by local laser heating of the film. The appearance of the supercurrent, which is driven by a thermally induced phase shift in the condensate wavefunction, is evidenced by analysis of the temporal evolution of the magnon density measured by means of Brillouin light scattering spectroscopy. Our findings offer opportunities for the investigation of room-temperature macroscopic quantum phenomena and their potential applications at ambient conditions.

  19. 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

  20. 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)].

  1. Dynamical Hartree-Fock-Bogoliubov theory of vortices in Bose-Einstein condensates at finite temperature

    SciTech Connect

    Wild, B. G.; Hutchinson, D. A. W.

    2011-06-15

    We present a method utilizing the continuity equation for the condensate density to make predictions of the precessional frequency of single off-axis vortices and of vortex arrays in Bose-Einstein condensates at finite temperature. We also present an orthogonalized Hartree-Fock-Bogoliubov (HFB) formalism. We solve the continuity equation for the condensate density self-consistently with the orthogonalized HFB equations and find stationary solutions in the frame rotating at this frequency. As an example of the utility of this formalism we obtain time-independent solutions for quasi-two-dimensional rotating systems in the corotating frame. We compare these results with time-dependent predictions where we simulate stirring of the condensate.

  2. Vector dark-antidark solitary waves in multicomponent Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Danaila, I.; Khamehchi, M. A.; Gokhroo, V.; Engels, P.; Kevrekidis, P. G.

    2016-11-01

    Multicomponent Bose-Einstein condensates exhibit an intriguing variety of nonlinear structures. In recent theoretical work [C. Qu, L. P. Pitaevskii, and S. Stringari, Phys. Rev. Lett. 116, 160402 (2016), 10.1103/PhysRevLett.116.160402], the notion of magnetic solitons has been introduced. Here we examine a variant of this concept in the form of vector dark-antidark solitary waves in multicomponent Bose-Einstein condensates (BECs). We first provide concrete experimental evidence for such states in an atomic BEC and subsequently illustrate the broader concept of these states, which are based on the interplay between miscibility and intercomponent repulsion. Armed with this more general conceptual framework, we expand the notion of such states to higher dimensions presenting the possibility of both vortex-antidark states and ring-antidark-ring (dark soliton) states. We perform numerical continuation studies, investigate the existence of these states, and examine their stability using the method of Bogoliubov-de Gennes analysis. Dark-antidark and vortex-antidark states are found to be stable for broad parametric regimes. In the case of ring dark solitons, where the single-component ring state is known to be unstable, the vector entity appears to bear a progressively more and more stabilizing role as the intercomponent coupling is increased.

  3. Spin and field squeezing in a spin-orbit coupled Bose-Einstein condensate

    PubMed Central

    Huang, Yixiao; Hu, Zheng-Da

    2015-01-01

    Recently, strong spin-orbit coupling with equal Rashba and Dresselhaus strength has been realized in neutral atomic Bose-Einstein condensates via a pair of Raman lasers. In this report, we investigate spin and field squeezing of the ground state in spin-orbit coupled Bose-Einstein condensate. By mapping the spin-orbit coupled BEC to the well-known quantum Dicke model, the Dicke type quantum phase transition is presented with the order parameters quantified by the spin polarization and occupation number of harmonic trap mode. This Dicke type quantum phase transition may be captured by the spin and field squeezing arising from the spin-orbit coupling. We further consider the effect of a finite detuning on the ground state and show the spin polarization and the quasi-momentum exhibit a step jump at zero detuning. Meanwhile, we also find that the presence of the detuning enhances the occupation number of harmonic trap mode, while it suppresses the spin and the field squeezing. PMID:25620051

  4. All-optical runaway evaporation to Bose-Einstein condensation

    NASA Astrophysics Data System (ADS)

    Clément, J.-F.; Brantut, J.-P.; Robert-de-Saint-Vincent, M.; Nyman, R. A.; Aspect, A.; Bourdel, T.; Bouyer, P.

    2009-06-01

    We demonstrate runaway evaporative cooling directly with a tightly confining optical-dipole trap and achieve fast production of condensates of 1.5×105 R87b atoms. Our scheme uses a misaligned crossed-beam far off-resonance optical-dipole trap (MACRO-FORT). It is characterized by independent control of the trap confinement and depth allowing forced all-optical evaporation in the runaway regime. Although our configuration is particularly well suited to the case of R87b atoms in a 1565 nm optical trap, where an efficient initial loading is possible, our scheme is general and will allow all-optical evaporative cooling at constant stiffness for every optically trappable atomic or even molecular species.

  5. Bose-Einstein condensates of bosonic Thomson atoms

    NASA Astrophysics Data System (ADS)

    Schneider, Tobias; Blümel, Reinhold

    1999-10-01

    A system of charged particles in a harmonic trap is a realization of Thomson's raisin cake model. Therefore, we call it a Thomson atom. Bosonic, fermionic and mixed Thomson atoms exist. In this paper we focus on bosonic Thomson atoms in isotropic traps. Approximating the exact ground state by a condensate we investigate ground-state properties at temperature T = 0 using the Hartree-Fock theory for bosons. In order to assess the quality of our mean-field approach we compare the Hartree-Fock results for bosonic Thomson helium with an exact diagonalization. In contrast to the weakly interacting Bose gas (alkali vapours) mean-field calculations are reliable in the limit of large particle density. The Wigner regime (low particle density) is discussed.

  6. Analysis of a Bose-Einstein Condensate Double-Well Atom Interferometer

    SciTech Connect

    Faust, Douglas K.; Reinhardt, William P.

    2010-12-10

    Motivated by an open theoretical question in Bose-Einstein condensate atom interferometry, we introduce a novel computational method to describe the condensate order parameter in the presence of a central barrier. We are able to follow the full dynamics of the system during the raising of a barrier, from a single macroscopically occupied ground state to a state where imaging shows a split density and, finally, to the observation of a phase-controlled interference pattern. We are able to discriminate between a mean-field and a two-mode state via the Penrose-Onsager criterion. By simulating the first such experiment, where in spite of the observed splitting of the condensate density there is never more than a single macroscopically occupied state, we provide a definitive interpretation of these systems as a novel many-body form of Young's double-slit experiment.

  7. Analysis of a Bose-Einstein condensate double-well atom interferometer.

    PubMed

    Faust, Douglas K; Reinhardt, William P

    2010-12-10

    Motivated by an open theoretical question in Bose-Einstein condensate atom interferometry, we introduce a novel computational method to describe the condensate order parameter in the presence of a central barrier. We are able to follow the full dynamics of the system during the raising of a barrier, from a single macroscopically occupied ground state to a state where imaging shows a split density and, finally, to the observation of a phase-controlled interference pattern. We are able to discriminate between a mean-field and a two-mode state via the Penrose-Onsager criterion. By simulating the first such experiment, where in spite of the observed splitting of the condensate density there is never more than a single macroscopically occupied state, we provide a definitive interpretation of these systems as a novel many-body form of Young's double-slit experiment.

  8. Analysis of a Bose-Einstein Condensate Double-Well Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Faust, Douglas K.; Reinhardt, William P.

    2010-12-01

    Motivated by an open theoretical question in Bose-Einstein condensate atom interferometry, we introduce a novel computational method to describe the condensate order parameter in the presence of a central barrier. We are able to follow the full dynamics of the system during the raising of a barrier, from a single macroscopically occupied ground state to a state where imaging shows a split density and, finally, to the observation of a phase-controlled interference pattern. We are able to discriminate between a mean-field and a two-mode state via the Penrose-Onsager criterion. By simulating the first such experiment, where in spite of the observed splitting of the condensate density there is never more than a single macroscopically occupied state, we provide a definitive interpretation of these systems as a novel many-body form of Young’s double-slit experiment.

  9. Optimized evaporative cooling for sodium Bose-Einstein condensation against three-body loss

    SciTech Connect

    Shobu, Takahiko; Yamaoka, Hironobu; Imai, Hiromitsu; Morinaga, Atsuo; Yamashita, Makoto

    2011-09-15

    We report on a highly efficient evaporative cooling optimized experimentally. We successfully created sodium Bose-Einstein condensates with 6.4x10{sup 7} atoms starting from 6.6x10{sup 9} thermal atoms trapped in a magnetic trap by employing a fast linear sweep of radio frequency at the final stage of evaporative cooling so as to overcome the serious three-body losses. The experimental results such as the cooling trajectory and the condensate growth quantitatively agree with the numerical simulations of evaporative cooling on the basis of the kinetic theory of a Bose gas carefully taking into account our specific experimental conditions. We further discuss theoretically a possibility of producing large condensates, more than 10{sup 8} sodium atoms, by simply increasing the number of initial thermal trapped atoms and the corresponding optimization of evaporative cooling.

  10. 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.

  11. Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein condensates

    SciTech Connect

    Rooney, S. J.; Blakie, P. B.; Bradley, A. S.; Anderson, B. P.

    2011-08-15

    We study the Kelvin mode excitations on a vortex line in a three-dimensional trapped Bose-Einstein condensate at finite temperature. Our stochastic Gross-Pitaevskii simulations show that the activation of these modes can be suppressed by tightening the confinement along the direction of the vortex line, leading to a strong suppression in the vortex decay rate as the system enters a regime of two-dimensional vortex dynamics. As the system approaches the condensation transition temperature, we find that the vortex decay rate is strongly sensitive to dimensionality and temperature, observing a large enhancement for quasi-two-dimensional traps. Three-dimensional simulations of the recent vortex dipole decay experiment of Neely et al.[Phys. Rev. Lett. 104, 160401 (2010)] confirm two-dimensional vortex dynamics and predict a dipole lifetime consistent with experimental observations and suppression of Kelvon-induced vortex decay in highly oblate condensates.

  12. Pair dynamics in the formation of molecules in a Bose-Einstein condensate

    SciTech Connect

    Naidon, Pascal; Masnou-Seeuws, Francoise

    2003-09-01

    We revisit the mean-field treatment of photoassociation and Feshbach resonances in a Bose-Einstein condensate previously used by various authors. Generalizing the Cherny and Shanenko approach [Phys. Rev. E 62, 1646 (2000)] where the finite size of the potentials is explicitly introduced, we develop a two-channel model for a mixed atomic-molecular condensate. Besides the individual dynamics of the condensed and noncondensed atoms, the model also takes into account their pair dynamics by means of pair wave functions. We show that the resulting set of coupled equations can be reduced to the usual coupled Gross-Pitaevskii equations when the time scale of the pair dynamics is short compared to that of the individual dynamics. Such time scales are discussed in the case of typical photoassociation experiments with cw lasers. We show that the individual dynamics plays a minor role, demonstrating the validity of the rates predicted by the usual models describing photoassociation in a nondegenerate gas.

  13. 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.

  14. 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.

  15. Vortex structures of rotating Bose-Einstein condensates in an anisotropic harmonic potential

    SciTech Connect

    Matveenko, S. I.

    2010-09-15

    We found an analytical solution for the vortex structure in a rapidly rotating trapped Bose-Einstein condensate in the lowest Landau level approximation. This solution is exact in the limit of a large number of vortices and is obtained for the case of a condensate in a anisotropic harmonic potential. The solution describes as limiting cases both a triangle vortex lattice in the symmetric potential trap and a quasi-one-dimensional structure of vortex rows in an asymmetric case, when the rotation frequency is very close to the lower trapping potential frequency. The shape of the density profile is found to be close to the Thomas-Fermi inverted paraboloid form, except in the vicinity of edges of a condensate cloud.

  16. 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.

  17. {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.

  18. 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.

  19. 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.

  20. Self-consistent theory of a Bose-Einstein condensate with impurity at finite temperature

    NASA Astrophysics Data System (ADS)

    Boudjemâa, Abdelâali

    2015-01-01

    We study the properties of Bose-Einstein condensate-impurity mixtures at finite temperatures employing the Balian-Vénéroni variational principle. The method leads to a set of coupled nonlinear equations of motion for the condensate and its normal and anomalous fluctuations on the one hand, and for the impurity on the other. We show that the obtained equations satisfy the energy and number conserving laws. Useful analytic expressions for the chemical potential and the radius of both the condensate and anomalous components are derived in the framework of the Thomas-Fermi approximation in a d-dimensional regime. The effects of the impurity on these quantities are discussed.

  1. Mechanism of stimulated Hawking radiation in a laboratory Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Wang, Yi-Hsieh; Jacobson, Ted; Edwards, Mark; Clark, Charles W.

    2017-08-01

    We model a sonic black-hole analog in a quasi-one-dimensional Bose-Einstein condensate, using a Gross-Pitaevskii equation matching the configuration of a recent experiment by Steinhauer [Nat. Phys. 10, 864 (2014), 10.1038/nphys3104]. The model agrees well with important features of the experimental observations, demonstrating their hydrodynamic nature. We find that a zero-frequency bow wave is generated at the inner (white-hole) horizon, which grows in proportion to the square of the background condensate density. The relative motion of the black- and white-hole horizons produces a Doppler shift of the bow wave at the black hole, where it stimulates the emission of monochromatic Hawking radiation. The mechanism is confirmed using temporal and spatial windowed Fourier spectra of the condensate. Mean field behavior similar to that in the experiment can thus be fully explained without the presence of self-amplifying Hawking radiation.

  2. 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.

  3. Full counting statistics of the interference contrast from independent Bose-Einstein condensates

    SciTech Connect

    Rath, Steffen Patrick; Zwerger, Wilhelm

    2010-11-15

    We show that the visibility in interference experiments with Bose-Einstein condensates is directly related to the condensate fraction. The probability distribution of the contrast over many runs of an interference experiment thus gives the full counting statistics of the condensed atom number. For two-dimensional Bose gases, we discuss the universal behavior of the probability distribution in the superfluid regime and provide analytical expressions for the distributions for both homogeneous and harmonically trapped samples. They are non-Gaussian and unimodal with a variance that is directly related to the superfluid density. In general, the visibility is a self-averaging observable only in the presence of long-range phase coherence. Close to the transition temperature, the visibility distribution reflects the universal order-parameter distribution in the vicinity of the critical point.

  4. Thermal friction on quantum vortices in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Moon, Geol; Kwon, Woo Jin; Lee, Hyunjik; Shin, Yong-il

    2015-11-01

    We investigate the dissipative dynamics of a corotating vortex pair in a highly oblate axisymmetric Bose-Einstein condensate trapped in a harmonic potential. The initial vortex state is prepared by creating a doubly charged vortex at the center of the condensate and letting it dissociate into two singly charged vortices. The separation of the vortex pair gradually increases over time and its increasing rate becomes higher with increasing the sample temperature T . The evolution of the vortex state is well described with a dissipative point vortex model including longitudinal friction on the vortex motion. For condensates of sodium atoms having a chemical potential of μ ≈kB×120 nK, we find that the dimensionless friction coefficient α increases from 0.01 to 0.03 over the temperature range of 200 nK

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Analogue cosmological particle creation: Quantum correlations in expanding Bose-Einstein condensates

    SciTech Connect

    Prain, Angus; Liberati, Stefano; Fagnocchi, Serena

    2010-11-15

    We investigate the structure of quantum correlations in an expanding Bose-Einstein condensate (BEC) through the analogue gravity framework. We consider both a 3+1 isotropically expanding BEC as well as the experimentally relevant case of an elongated, effectively 1+1 dimensional, expanding condensate. In this case we include the effects of inhomogeneities in the condensate, a feature rarely included in the analogue gravity literature. In both cases we link the BEC expansion to a simple model for an expanding spacetime and then study the correlation structure numerically and analytically (in suitable approximations). We also discuss the expected strength of such correlation patterns and experimentally feasible BEC systems in which these effects might be detected in the near future.

  10. Critical velocity for vortex shedding in a Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Kwon, Woo Jin; Moon, Geol; Seo, Sang Won; Shin, Y.

    2015-05-01

    We present measurements of the critical velocity for vortex shedding in a highly oblate Bose-Einstein condensate with a moving repulsive Gaussian laser beam. As a function of the barrier height V0, the critical velocity vc shows a dip structure having a minimum at V0≈μ , where μ is the chemical potential of the condensate. At fixed V0≈7 μ , we observe that the ratio of vc to the speed of sound cs monotonically increases for decreasing σ /ξ , where σ is the beam width and ξ is the condensate healing length. We explain our results with the density reduction effect of the soft boundary of the Gaussian obstacle, based on the local Landau criterion for superfluidity. The measured value of vc/cs with our stiffest obstacle is about 0.4, which is in good agreement with theoretical predictions for a two-dimensional superflow past a circular cylinder.

  11. Wave function of a microwave-driven Bose-Einstein magnon condensate

    SciTech Connect

    Rezende, Sergio M.

    2010-01-01

    It has been observed experimentally that a magnon gas in a film of yttrium-iron garnet at room temperature driven by a microwave field exhibits Bose-Einstein condensation (BEC) when the driving power exceeds a critical value. In a previous paper we presented a model for the dynamics of the magnon system in wave-vector space that provides firm theoretical support for the formation of the BEC. Here we show that the wave function of the magnon condensate in configuration space satisfies a Gross-Pitaevskii equation similarly to other BEC systems. The theory is consistent with the previous model in wave-vector space, and its results are in qualitative agreement with recent measurements of the spatial distribution of the magnon condensate driven by a nonuniform microwave field.

  12. 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.

  13. 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.

  14. 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.

  15. Decoherence effects in Bose-Einstein condensate interferometry I. General theory

    SciTech Connect

    Dalton, B.J.

    2011-03-15

    Research Highlights: > Theory of dephasing, decoherence effects for Bose-Einstein condensate interferometry. > Applies to single component, two mode condensate in double potential well. > Phase space theory using Wigner, positive P representations for condensate, non-condensate fields. > Stochastic condensate, non-condensate field equations and properties of noise fields derived. > Based on mean field theory with condensate modes given by generalised Gross-Pitaevskii equations. - Abstract: The present paper outlines a basic theoretical treatment of decoherence and dephasing effects in interferometry based on single component Bose-Einstein condensates in double potential wells, where two condensate modes may be involved. Results for both two mode condensates and the simpler single mode condensate case are presented. The approach involves a hybrid phase space distribution functional method where the condensate modes are described via a truncated Wigner representation, whilst the basically unoccupied non-condensate modes are described via a positive P representation. The Hamiltonian for the system is described in terms of quantum field operators for the condensate and non-condensate modes. The functional Fokker-Planck equation for the double phase space distribution functional is derived. Equivalent Ito stochastic equations for the condensate and non-condensate fields that replace the field operators are obtained, and stochastic averages of products of these fields give the quantum correlation functions that can be used to interpret interferometry experiments. The stochastic field equations are the sum of a deterministic term obtained from the drift vector in the functional Fokker-Planck equation, and a noise field whose stochastic properties are determined from the diffusion matrix in the functional Fokker-Planck equation. The stochastic properties of the noise field terms are similar to those for Gaussian-Markov processes in that the stochastic averages of odd

  16. Synergy dynamics of vortices and solitons in an atomic Bose-Einstein condensate excited by an oscillating potential

    SciTech Connect

    Fujimoto, Kazuya; Tsubota, Makoto

    2010-10-15

    The hydrodynamics of quantized vortices and solitons in an atomic Bose-Einstein condensate excited by an oscillating potential are studied by numerically solving the two-dimensional Gross-Pitaevskii equation. The oscillating potential keeps nucleating vortex dipoles, whose impulses alternately change their direction synchronously with the oscillation of the potential. This leads to synergy dynamics of vortices and solitons in quantum fluids.

  17. Explicit solutions to an effective Gross-Pitaevskii equation: One-dimensional Bose-Einstein condensate in specific traps

    SciTech Connect

    Kengne, E.; Liu, X. X.; Liu, W. M.; Malomed, B. A.; Chui, S. T.

    2008-02-15

    An effective Gross-Pitaevskii equation, which describes the dynamics of quasi-one-dimensional Bose-Einstein condensates in specific potential traps, is considered, and new families of exact solutions are reported, which include periodic and solitary waves. The solutions are applied to the description of BEC patterns trapped in optical-lattice potentials.

  18. 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.

  19. 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.

  20. 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).