A Model for Macroscopic Quantum Tunneling of Bose-Einstein Condensate with Attractive Interaction
YAN Ke-Zhu; TAN Wei-Han
2000-01-01
Based on the numerical wave function solutions of neutral atoms with attractive interaction in a harmonic trap, we propose an exactly solvable model for macroscopic quantum tunneling of a Bose condensate with attractive interaction. We calculate the rate of macroscopic quantum tunneling from a metastable condensate state to the collapse state and analyze the stability of the attractive Bose-Einstein condensation.
Collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction
Chavanis, Pierre-Henri
2016-01-01
We study the collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction. Equilibrium states in which the gravitational attraction and the attraction due to the self-interaction are counterbalanced by the quantum pressure exist only below a maximum mass $M_{\\rm max}=1.012\\hbar/\\sqrt{Gm|a_s|}$ where $a_sM_{\\rm max}$ the system is expected to collapse and form a black hole. We study the collapse dynamics by making a Gaussian ansatz for the wave function. We find tha...
Collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction
Chavanis, Pierre-Henri
2016-01-01
We study the collapse of a self-gravitating Bose-Einstein condensate with attractive self-interaction. Equilibrium states in which the gravitational attraction and the attraction due to the self-interaction are counterbalanced by the quantum pressure exist only below a maximum mass $M_{\\rm max}=1.012\\hbar/\\sqrt{Gm|a_s|}$ where $a_sM_{\\rm max}$ the system is expected to collapse and form a black hole. We study the collapse dynamics by making a Gaussian ansatz for the wave function. We find that the collapse time scales as $(M/M_{\\rm max}-1)^{-1/4}$ for $M\\rightarrow M_{\\rm max}^+$ and as $M^{-1/2}$ for $M\\gg M_{\\rm max}$. We apply our results to standard axions with mass $m=10^{-4}\\, {\\rm eV}/c^2$ and scattering length $a_s=-5.8\\times 10^{-53}\\, {\\rm m}$ for which $M_{\\rm max}=6.5\\times 10^{-14}M_{\\odot}$ and $R=3.3\\times 10^{-4}\\, R_{\\odot}$. We confirm our previous claim that bosons with attractive self-interaction, such as standard axions, may form low mass stars but cannot form dark matter halos of relevan...
Vortices in Attractive Bose-Einstein Condensates in Two Dimensions
The form and stability of quantum vortices in Bose-Einstein condensates with attractive atomic interactions is elucidated. They appear as ring bright solitons, and are a generalization of the Townes soliton to nonzero winding number m. An infinite sequence of radially excited stationary states appear for each value of m, which are characterized by concentric matter-wave rings separated by nodes, in contrast to repulsive condensates, where no such set of states exists. It is shown that robustly stable as well as unstable regimes may be achieved in confined geometries, thereby suggesting that vortices and their radial excited states can be observed in experiments on attractive condensates in two dimensions
Bose-Einstein atoms in atomic traps with predominantly attractive two-body interactions
Using the Perron-Frobenius theorem, we prove that the results by Wilkin, Gunn, and Smith [Phys. Rev. Lett. 80, 2265 (1998)] for the ground states at angular momentum L of N harmonically trapped Bose atoms, interacting via weak attractive δ2(r) forces, are valid for a broad class of predominantly attractive interactions V(r), not necessarily attractive for any r. This class is described by sufficient conditions on the two-body matrix elements of the potential V(r). It includes, in particular, the Gaussian attraction of arbitrary radius, -1/r-Coulomb and log(r)-Coulomb forces, as well as all the short-range interactions satisfying inequality ∫d2r-vectorV(r)<0. In the precollapse regime, the angular momentum L is concentrated in the collective 'center-of-mass' mode, and there is no condensation at high L
Observation of attractive and repulsive polarons in a Bose-Einstein condensate
Jørgensen, Nils B.; Wacker, Lars; Skalmstang, Kristoffer T.;
2016-01-01
for an impurity interacting with a Bose-Einstein condensate (BEC). We measure the energy of the impurity both for attractive and repulsive interactions with the BEC, and find excellent agreement with theories that incorporate three-body correlations, both in the weak-coupling limits and across...
Attraction-induced dynamical stability of a Bose-Einstein condensate in a nonlinear lattice
Dasgupta, Raka; Venkatesh, B. Prasanna; Watanabe, Gentaro
2016-06-01
We study multiple-period Bloch states of a Bose-Einstein condensate with spatially periodic interatomic interaction. Solving the Gross-Pitaevskii equation for the continuum model, and also using a simplified discrete version of it, we investigate the energy-band structures and the corresponding stability properties. We observe an "attraction-induced dynamical stability" mechanism caused by the localization of the density distribution in the attractive domains of the system and the isolation of these higher-density regions. This makes the superfluid stable near the zone boundary and also enhances the stability of higher-periodic states if the nonlinear interaction strength is sufficiently high.
Observation of Attractive and Repulsive Polarons in a Bose-Einstein Condensate
Jørgensen, Nils B.; Wacker, Lars; Skalmstang, Kristoffer T.;
2016-01-01
The behavior of a mobile impurity particle interacting with a quantum-mechanical medium is of fundamental importance in physics. Due to the great flexibility of atomic gases, our understanding of the impurity problem has improved dramatically since it was realized experimentally in a particularly...... for an impurity interacting with a Bose-Einstein condensate (BEC). We measure the energy of the impurity both for attractive and repulsive interactions with the BEC, and find excellent agreement with theories that incorporate three-body correlations, both in the weak-coupling limits and across unitarity. Our...
Observation of attractive and repulsive polarons in a Bose-Einstein condensate
Jørgensen, Nils Byg
2016-01-01
The problem of an impurity particle moving through a bosonic medium plays a fundamental role in physics, ranging from organic electronics to the Standard Model. However, despite intense theoretical investigation, the canonical scenario of a mobile impurity immersed in a Bose-Einstein condensate...... (BEC) has not yet been realized. Here, we use radio frequency spectroscopy of ultracold bosonic 39K atoms to experimentally demonstrate the existence of a well-defined quasiparticle state of an impurity interacting with a BEC. We measure the energy of the impurity both for attractive and repulsive...
39K Bose-Einstein condensate with tunable interactions.
Roati, G.; Zaccanti, M.; D'Errico, C; Catani, Jacopo; Modugno, Michele; Simoni, Andrea; Inguscio, M.; Inguscio, Massimo
2007-01-01
We produce a Bose-Einstein condensate of 39K atoms. Condensation of this species with a naturally small and negative scattering length is achieved by a combination of sympathetic cooling with 87Rb and direct evaporation, exploiting the magnetic tuning of both inter- and intraspecies interactions at Feshbach resonances. We explore the tunability of the self-interactions by studying the expansion and the stability of the condensate. We find that a 39K condensate is interesting for future experi...
Generation and interaction of solitons in Bose-Einstein condensates
Burger, S.; Carr, L. D.; Ohberg, P.; Sengstock, K.; Sanpera, A.
2002-01-01
Generation, interaction and detection of dark solitons in Bose-Einstein condensates is considered. In particular, we focus on the dynamics resulting from phase imprinting and density engineering. The generation of soliton pairs as well as their interaction is also considered. Finally, motivated by the recent experimental results of Cornish et al. (Phys. Rev Lett. 85, 1795, 2000), we analyze the stability of dark solitons under changes of the scattering length and thereby demonstrate a new way...
Macroscopic quantum tunneling of Bose-Einstein condensates with long-range interaction
Marquardt, Kai; Wieland, Pascal; Häfner, Rolf; Cartarius, Holger; Main, Jörg; Wunner, Günter
2012-01-01
The ground state of Bose-Einstein condensates with attractive particle interaction is metastable. One of the decay mechanisms of the condensate is a collapse by macroscopic quantum tunneling, which can be described by the bounce trajectory as solution of the time-dependent Gross-Pitaevskii equation in imaginary time. For condensates with an electromagnetically induced gravity-like interaction the bounce trajectory is computed with an extended variational approach using coupled Gaussian functi...
A general approach to the Bose-einstein condensation of neutral atoms with repellent interaction
A general approach to the Bose-Einstein condensation of neutral atoms with repellent interaction is presented. Especially in the case of free atoms (V = 0) with repellent interaction, an exact solution for the atom's wave function can be derived, and therefore the calculation of atom's Bose-Einstein condensation is completed
Collapse of Bose-Einstein condensate with dipole-dipole interactions
Lushnikov, Pavel M.
2002-01-01
A dynamics of Bose-Einstein condensate of a gas of bosonic particles with long-range dipole-dipole interactions in a harmonic trap is studied. Sufficient analytical criteria are found both for catastrophic collapse of Bose-Einstein condensate and for long-time condensate existence. Analytical criteria are compared with variational analysis.
Resistive flow in a weakly interacting Bose-Einstein condensate.
Jendrzejewski, F; Eckel, S; Murray, N; Lanier, C; Edwards, M; Lobb, C J; Campbell, G K
2014-07-25
We report the direct observation of resistive flow through a weak link in a weakly interacting atomic Bose-Einstein condensate. Two weak links separate our ring-shaped superfluid atomtronic circuit into two distinct regions, a source and a drain. Motion of these weak links allows for creation of controlled flow between the source and the drain. At a critical value of the weak link velocity, we observe a transition from superfluid flow to superfluid plus resistive flow. Working in the hydrodynamic limit, we observe a conductivity that is 4 orders of magnitude larger than previously reported conductivities for a Bose-Einstein condensate with a tunnel junction. Good agreement with zero-temperature Gross-Pitaevskii simulations and a phenomenological model based on phase slips indicate that the creation of excitations plays an important role in the resulting conductivity. Our measurements of resistive flow elucidate the microscopic origin of the dissipation and pave the way for more complex atomtronic devices. PMID:25105631
Mean-field model of interaction between bright vortex solitons in Bose-Einstein condensates
Using the explicit numerical solution of the axially symmetric Gross-Pitaevskii equation we study the dynamics of interaction among vortex solitons in a rotating matter-wave bright soliton train in a radially trapped and axially free Bose-Einstein condensate to understand certain features of the experiment by Strecker et al (2002 Nature 417 150). In a soliton train, solitons of opposite phase (phase δ = π) repel and stay apart without changing shape; solitons with π = 0 attract, interact and coalesce, but eventually come out; solitons with a general δ usually repel but interact inelastically by exchanging matter. We study this and suggest future experiments with vortex solitons
85Rb tunable-interaction Bose-Einstein condensate machine
We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of 85Rb with tunable interparticle interactions. We use sympathetic cooling with 87Rb 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 85Rb atoms. Typical 85Rb condensates contain 4x104 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 85Rb BEC machine at JILA, which we discuss at the end of this article.
Effect of interaction strength on gap solitons of Bose-Einstein condensates in optical lattices
Yang Ru-Shu; Yang Jiang-He
2008-01-01
We have developed a systematic analytical approach to the study on the dynamic properties of the linear and the nonlinear excitations for quasi-one-dimensional Bose-Einstein condensate trapped in optical lattices. A novel linear dispersion relation and an algebraic soliton solution of the condensate are derived analytically under consideration of Bose-Einstein condensate with a periodic potential. By analysing the soliton solution, we find that the interatomic interaction strength has an important effect on soliton dynamic properties of Bose-Einstein condensate.
Observation of Attractive and Repulsive Polarons in a Bose-Einstein Condensate
Jørgensen, Nils B.; Wacker, Lars; Skalmstang, Kristoffer T.; Parish, Meera M.; Levinsen, Jesper; Christensen, Rasmus S.; Bruun, Georg M.; Arlt, Jan J.
2016-07-01
The problem of an impurity particle moving through a bosonic medium plays a fundamental role in physics. However, the canonical scenario of a mobile impurity immersed in a Bose-Einstein condensate (BEC) has not yet been realized. Here, we use radio frequency spectroscopy of ultracold bosonic 39K atoms to experimentally demonstrate the existence of a well-defined quasiparticle state of an impurity interacting with a BEC. We measure the energy of the impurity both for attractive and repulsive interactions, and find excellent agreement with theories that incorporate three-body correlations, both in the weak-coupling limits and across unitarity. The spectral response consists of a well-defined quasiparticle peak at weak coupling, while for increasing interaction strength, the spectrum is strongly broadened and becomes dominated by the many-body continuum of excited states. Crucially, no significant effects of three-body decay are observed. Our results open up exciting prospects for studying mobile impurities in a bosonic environment and strongly interacting Bose systems in general.
Semiclassical dynamics of quasi-one-dimensional, attractive Bose-Einstein condensates
Tovbis, Alexander, E-mail: atovbis@pegasus.cc.ucf.ed [Department of Mathematics, University of Central Florida, Orlando, FL 32816 (United States); Hoefer, M.A. [Department of Mathematics, North Carolina State University, Raleigh, NC 27695 (United States)
2011-01-17
The strongly interacting regime for attractive Bose-Einstein condensates (BECs) tightly confined in an extended cylindrical trap is studied. For appropriately prepared, non-collapsing BECs, the ensuing dynamics are found to be governed by the one-dimensional focusing Nonlinear Schroedinger equation (NLS) in the semiclassical (small dispersion) regime. In spite of the modulational instability of this regime, some mathematically rigorous results on the strong asymptotics of the semiclassical limiting solutions were obtained recently. Using these results, 'implosion-like' and 'explosion-like' events are predicted whereby an initial hump focuses into a sharp spike which then expands into rapid oscillations. Seemingly related behavior has been observed in three-dimensional experiments and models, where a BEC with a sufficient number of atoms undergoes collapse. The dynamical regimes studied here, however, are not predicted to undergo collapse. Instead, distinct, ordered structures, appearing after the 'implosion', yield interesting new observables that may be experimentally accessible.
Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates
The interaction of ring dark solitons/vortexes with the ring-shaped repulsive and attractive impurities in two-dimensional Bose-Einstein condensates is investigated numerically. Very rich interaction phenomena are obtained, i.e., not only the interaction between the ring soliton and the impurity, but also the interaction between vortexes and the impurity. The interaction characters, i.e., snaking of ring soliton, quasitrapping or reflection of ring soliton and vortexes by the impurity, strongly depend on initial ring soliton velocity, impurity strength, initial position of ring soliton and impurity. The numerical results also reveal that ring dark solitons/vortexes can be trapped and dragged by an adiabatically moving attractive ring impurity
Complex solitons in Bose-Einstein condensates with two- and three-body interactions
Roy, Utpal [Universita di Camerino, I-62032 Camerino (Italy); Atre, Rajneesh [Jaypee Institute of Engineering and Technology, Guna 473 226 (India); Sudheesh, C [Indian Institute of Science, Bangalore 560 012 (India); Kumar, C Nagaraja [Punjab University, Chandigarh 160 014 (India); Panigrahi, Prasanta K, E-mail: utpal.roy@unicam.i, E-mail: utpalphys@gmail.co, E-mail: prasanta@prl.res.i [Physical Research Laboratory, Ahmedabad 380 009 (India)
2010-01-28
For the first time, we find the complex solitons for a quasi-one-dimensional Bose-Einstein condensate with two- and three-body interactions. These localized solutions are characterized by a power law behaviour. Both dark and bright solitons can be excited in the experimentally allowed parameter domain, when two- and three-body interactions are, respectively, repulsive and attractive. The dark solitons travel with a constant speed, which is quite different from the Lieb mode, where profiles with different speeds, bounded above by sound velocity, can exist for specified interaction strengths. We also study the properties of these solitons in the presence of harmonic confinement with time-dependent nonlinearity and loss. The modulational instability and the Vakhitov-Kolokolov criterion of stability are also studied.
Casimir force on an interacting Bose-Einstein condensate
Biswas, Shyamal; Majumder, Dwipesh; Saha, Kush [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Bhattacharjee, J K [S.N. Bose National Centre for Basic Sciences, Sector 3, JD Block, Salt Lake, Kolkata 700098 (India); Chakravarty, Nabajit, E-mail: tpsb2@iacs.res.i [Positional Astronomy Centre, Block AQ, Plot 8, Sector 5, Salt Lake, Kolkata 700091 (India)
2010-04-28
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wavefunction as well as for the phonon field. We have shown that the condensate wavefunction (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of the Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
Casimir force on interacting Bose-Einstein condensate
Biswas, Shyamal; Bhattacharjee, J K; Majumder, Dwipesh; Saha, Kush; Chakravarty, Nabajit
2009-01-01
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate (BEC) which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wave function as well as for the phonon field. We have shown that, the condensate wave function (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
Droplet formation in a Bose-Einstein condensate with strong dipole-dipole interaction
Xi, Kui-Tian; Saito, Hiroki
2016-01-01
Motivated by the recent experiment [H. Kadau et al., arXiv:1508.05007], we study roton instability and droplet formation in a Bose-Einstein condensate of 164Dy atoms with strong magnetic dipole-dipole interaction. We numerically solve the cubic-quintic Gross-Pitaevskii equation with dipole-dipole interaction, and show that the three-body interaction plays a significant role in the formation of droplet patterns. We numerically demonstrate the formation of droplet patterns and crystalline structures, decay of droplets, and hysteresis behavior, which are in good agreement with the experiment. Our numerical simulations provide the first prediction on the values of the three-body interaction in a 164Dy Bose-Einstein condensate. We also predict that the droplets remain stable during the time-of-flight expansion. From our results, further experiments investigating the three-body interaction in dipolar quantum gases are required.
Interaction Effects on Number Fluctuations in a Bose-Einstein Condensate of Light
van der Wurff, E. C. I.; de Leeuw, A. -W.; Duine, R. A.; Stoof, H.T.C.
2014-01-01
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 discuss possible mechanisms fo...
Interaction effects on number fluctuations in a Bose-Einstein condensate of light.
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. PMID:25302898
We study the ground states of rotating atomic Bose-Einstein condensates with dipolar interactions. We present the results of numerical studies on a periodic geometry which show vortex lattice ground states of various symmetries: triangular and square vortex lattices, ''stripe crystal,'' and ''bubble crystal.'' We present the phase diagram (for systems with a large number of vortices) as a function of the ratio of dipolar to contact interactions and of the chemical potential. We discuss the experimental requirements for observing transitions between vortex lattice ground states via dipolar interactions. We finally investigate the stability of mean-field supersolid phases of a quasi-two-dimensional nonrotating Bose gas with dipolar interactions
The Bose-Einstein correlations in deep inelastic μ p interactions at 280 GeV
Arneodo, M.; Arvidson, A.; Aubert, J. J.; Badelek, B.; Beaufays, J.; Bee, C. P.; Benchouk, C.; Berghoff, G.; Bird, I.; Blum, D.; Böhm, E.; de Bouard, X.; Brasse, F. W.; Braun, H.; Broll, C.; Brown, S.; Brück, H.; Calen, H.; Chima, J. S.; Ciborowski, J.; Cliftt, R.; Coignet, G.; Combley, F.; Coughlan, J.; D'Agostini, G.; Dahlgren, S.; Dengler, F.; Derado, I.; Dreyer, T.; Drees, J.; Düren, M.; Eckardt, V.; Edwards, A.; Edwards, M.; Ernst, T.; Eszes, G.; Favier, J.; Ferrero, M. I.; Figiel, J.; Flauger, W.; Foster, J.; Gabathuler, E.; Gajewski, J.; Gamet, R.; Gayler, J.; Geddes, N.; Grafström, P.; Grard, F.; Haas, J.; Hagberg, E.; Hasert, F. J.; Hayman, P.; Heusse, P.; Jaffre, M.; Jacholkowska, A.; Janata, F.; Jancso, G.; Johnson, A. S.; Kabuss, E. M.; Kellner, G.; Korbel, V.; Krüger, J.; Kullander, S.; Landgraf, U.; Lanske, D.; Loken, J.; Long, K.; Maire, M.; Malecki, P.; Manz, A.; Maselli, S.; Mohi, W.; Montanet, F.; Montgomery, H. E.; Nagy, E.; Nassalski, J.; Norton, P. R.; Oakham, F. G.; Osborne, A. M.; Osborne, L. S.; Pascaud, C.; Pawlik, B.; Payre, P.; Peroni, C.; Peschel, H.; Pessard, H.; Pettingale, J.; Pietrzyk, B.; Pönsgen, B.; Pötsch, M.; Renton, P.; Ribarics, P.; Rith, K.; Rondio, E.; Sandacz, A.; Scheer, M.; Schlagböhmer, A.; Schiemann, H.; Schmitz, N.; Schneegans, M.; Sholz, M.; Schröder, T.; Schouten, M.; Schultze, K.; Sloan, T.; Stier, H. E.; Studt, M.; Taylor, G. N.; Thenard, J. M.; Thompson, J. C.; de La Torre, A.; Toth, J.; Urban, L.; Urban, L.; Wallucks, W.; Whalley, M.; Wheeler, S.; Williams, W. S. C.; Wimpenny, S. J.; Windmolders, R.; Wolf, G.
1986-03-01
The Bose-Einstein correlation has been observed for pions in deep inelastic μ p interactions at 280 GeV. The importance of non-interference correlations in the sample of like charge pion pairs and in the sample used for reference is discussed. The pion emission region is found to be roughly spherical in the pair rest frame with a radius of 0.46 0.84 fm and the chaos factor λ is 0.60 1.08.
Bose-Einstein correlations in αα,pp and panti p interactions
Bose-Einstein correlations between pions produced in the central region of rapidity in αα, pp and panti p interactions have been studied at the ISR. The parameters r and tauc - often interpreted as the radius and depth of the π-emitting region - are found to be independent of incident particle type but to depend on the mean charged multiplicity. In high multiplicity events, the pions appear to originate from a larger space - time region. (orig.)
Xiong Bo; Liu Xun-Xu
2007-01-01
This paper studies the Josephson-like tunnelling in two-component Bose-Einstein condensates coupled with microwave field, which is in respond to various attractive and repulsive atomic interaction under the various aspect ratio of trapping potential. It is very interesting to find that the dynamic of Josephson-like tunnelling can be controlled from fast damped oscillations to nondamped oscillation, and relative number of atoms changes from asymmetric occupation to symmetric occupation correspondingly.
Ground state property of Bose-Einstein gas for arbitrary power low interaction
Hiramoto, Makoto
2002-01-01
We study Bose-Einstein gas for an arbitrary power low interaction $C_{\\alpha}r^{-\\alpha}$. This is done by the Hartree Fock Bogoliubov (HFB) approach at $T \\le T_{c}$ and the mean field approach at $T>T_{c}$. Especially, we investigate the ground state property of Bose gas interacting through the Van der Waals $-C_{6}r^{-6}$ plus $C_{3}r^{-3}$ interactions. We show that the ground state under this interaction is stable if the ratio of coupling constants is larger than that of the critical cur...
Bose-Einstein condensation of trapped atoms with dipole interactions
The path-integral Monte Carlo method is used to simulate dilute trapped Bose gases and to investigate the equilibrium properties at finite temperatures. The quantum particles have a long-range dipole-dipole interaction and a short-range s-wave interaction. Using an anisotropic pseudopotential for the long-range dipolar interaction and a hard-sphere potential for the short-range s-wave interaction, we calculate the energetics and structural properties as a function of temperature and the number of particles. Also, in order to determine the effects of dipole-dipole forces and the influence of the trapping field on the dipolar condensate, we use two cylindrically symmetric harmonic confinements (a cigar-shaped trap and a disk-shaped trap). We find that the net effect of dipole-dipole interactions is governed by the trapping geometry. For a cigar-shaped trap, the net contribution of dipolar interactions is attractive and the shrinking of the density profiles is observed. For a disk-shaped trap, the net effect of long-range dipolar forces is repulsive and the density profiles expand
胡正峰; 杜春光; 李师群
2003-01-01
We investigate the stimulated Raman adiabatic passage for Bose-Einstein condensate (BEG) states which are trapped in different potential wells or two ground states of BEG in the same trap. We consider that lasers are nearly resonant with the atomic transitions. The difference of population transfer processes between BEG atoms and usual atoms is that the atomic interaction of the BEG atoms can cause some nonadiabatic effects, which may degrade the process. But with suitable detunings of laser pulses, the effects can be remedied to some extent according to different atomic interactions.
Bose-Einstein condensation of trapped atoms with dipole interactions
Nho, Kwangsik; Landau, D. P.
2005-01-01
The path integral Monte Carlo method is used to simulate dilute trapped Bose gases and to investigate the equilibrium properties at finite temperatures. The quantum particles have a long-range dipole-dipole interaction and a short-range s-wave interaction. Using an anisotropic pseudopotential for the long-range dipolar interaction and a hard-sphere potential for the short-range s-wave interaction, we calculate the energetics and structural properties as a function of temperature and the numbe...
In this paper an influence of electron-phonon interaction screening on the critical temperature of high-temperature cuprate superconductors is studied within the framework of extended Holstein model and on the basis of Bose-Einstein condensation of ideal gas of bipolarons. (authors)
YU; Xuecai; YE; Yutang; WU; Yunfeng; XIE; Kang; CHENG; Lin
2005-01-01
The critical temperature of Bose-Einstein condensation at minimum momentum state for weakly interacting Bose gases in a power-law potential and the deviation of the critical temperature from ideal bose gas are studied. The effect of interaction on the critical temperature is ascribed to the ratiao α/λc, where α is the scattering length for s wave and λc is de Broglie wavelength at critical temperature. As α/λc<<1/(2π)2, the interaction is negligible. The presented deviation of the critical temperature for three dimensional harmonic potential is well in agreement with recent measurement of critical temperature for 87Rb bose gas trapped in a harmonic well.
Rayleigh surface wave interaction with the 2D exciton Bose-Einstein condensate
Boev, M. V.; Kovalev, V. M., E-mail: vadimkovalev@isp.nsc.ru [Russian Academy of Sciences, Institute of Semiconductor Physics, Siberian Branch (Russian Federation)
2015-06-15
We describe the interaction of a Rayleigh surface acoustic wave (SAW) traveling on the semiconductor substrate with the excitonic gas in a double quantum well located on the substrate surface. We study the SAW attenuation and its velocity renormalization due to the coupling to excitons. Both the deformation potential and piezoelectric mechanisms of the SAW-exciton interaction are considered. We focus on the frequency and excitonic density dependences of the SAW absorption coefficient and velocity renormalization at temperatures both above and well below the critical temperature of Bose-Einstein condensation of the excitonic gas. We demonstrate that the SAW attenuation and velocity renormalization are strongly different below and above the critical temperature.
Dynamics and Interaction of Vortex Lines in an Elongated Bose-Einstein Condensate.
Serafini, S; Barbiero, M; Debortoli, M; Donadello, S; Larcher, F; Dalfovo, F; Lamporesi, G; Ferrari, G
2015-10-23
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. PMID:26551093
Quantum Statistical Behaviors of Interaction of an Atomic Bose-Einstein Condensate with Laser
YU Zhao-Xian; JIAO Zhi-Yong
2001-01-01
We have investigated quantum statistical behaviors of photons and atoms in interaction of an atomic Bose Einstein condensate with quantized laser field. When the quantized laser field is initially prepared in a superposition state which exhibits holes in its photon-number distribution, while the atomic field is initially in a Fock state, it is found that there is energy exchange between photons and atoms. For the input and output states, the photons and atoms may exhibit the sub-Poissonian distribution. The input and output laser fields may exhibit quadrature squeezing, but for the atomic field, only the output state exhibits quadrature squeezing. It is shown that there exists the violation of the Cauchy-Schwartz inequality, which means that the correlation between photons and atoms is nonclassical.``
Interaction of a Bose-Einstein Condensate and a Superconductor via Eddy Currents
Sapina, Igor; Dahm, Thomas
2013-01-01
We study center-of-mass oscillations of a dipolar Bose-Einstein condensate in the vicinity of a superconducting surface. We show that the magnetic field of the magnetic dipoles induces eddy currents in the superconductor, which act back on the Bose-Einstein condensate. This leads to a shift of its oscillation frequency and to an anharmonic coupling of the Bose-Einstein condensate with the superconductor. The anharmonicity creates a coupling to one of the collective modes of the condensate tha...
Bright soliton trains of trapped Bose-Einstein condensates
Al Khawaja, U.; Stoof, H. T. C.; Hulet, R. G.; Strecker, K.E.; Patridge, G.B.
2002-01-01
We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate.
Competing interactions in population-imbalanced two-component Bose-Einstein condensates
Galteland, Peder Notto; Sudbø, Asle
2016-08-01
We consider a two-component Bose-Einstein condensate with and without synthetic "spin-orbit" interactions in two dimensions. Density and phase fluctuations of the condensate are included, allowing us to study the impact of thermal fluctuations and density-density interactions on the physics originating with spin-orbit interactions. In the absence of spin-orbit interactions, we find that intercomponent density interactions deplete the minority condensate. The thermally driven phase transition is driven by coupled density and phase-fluctuations, but is nevertheless shown to be a phase-transition in the Kosterlitz-Thouless universality class with close to universal amplitude ratios irrespective of whether both the minority- and majority condensates exist in the ground state, or only one condensate exists. In the presence of spin-orbit interactions we observe three separate phases, depending on the strength of the spin-orbit coupling and intercomponent density-density interactions: a phase-modulated phase with uniform amplitudes for small intercomponent interactions, a completely imbalanced, effectively single-component condensate for intermediate spin-orbit coupling strength and sufficiently large intercomponent interactions, and a phase-modulated and amplitude-modulated phase for sufficiently large values of both the spin-orbit coupling and the intercomponent density-density interactions. The phase that is modulated by a single q -vector only is observed to transition into an isotropic liquid through a strong depinning transition with periodic boundary conditions, which weakens with open boundaries.
Mach-Zehnder interferometry with interacting Bose-Einstein condensates in a double-well potential
Mach-Zehnder interferometry with interacting Bose-Einstein condensates in a double-well potential Particle-wave duality has enabled the construction of interferometers for massive particles such as electrons, neutrons, atoms or molecules. Implementing atom interferometry has required the development of analogues to the optical beam-splitters, phase shifters or recombiners to enable the coherent, i.e. phase-preserving manipulation of quantum superpositions. While initially demonstrating the wave nature of particles, atom interferometers have evolved into some of the most advanced devices for precision measurement, both for technological applications and tests of the fundamental laws of nature. Bose- Einstein condensates (BEC) of ultracold atoms are particular matter waves: they exhibit a collective many-body wave function and macroscopic coherence properties. As such, they have often been considered as an analogue to optical laser elds and it is natural to wonder whether BECs can provide to atom interferometry a similar boost as the laser brought to optical interferometry. One fundamental dierence between atomic BECs and lasers elds is the presence of atomic interactions, yielding an intrinsic non-linearity. On one hand, interactions can lead to eects destroying the phase coherence and limiting the interrogation time of trapped BEC interferometers. On the other hand, they can be used to generate nonclassical (e.g. squeezed) states to improve the sensitivity of interferometric measurements beyond the standard quantum limit (SQL). In this thesis, we present the realization of a full Mach-Zehnder interferometric sequence with trapped, interacting BECs con ned on an atom chip. Our interferometer relies on the coherent manipulation of a BEC in a magnetic double-well potential. For this purpose, we developed a novel type of matter-wave recombiner, an element which so far was missing in BEC atom optics. We have been able to exploit interactions to generate a squeezed
The Bose-Einstein correlations in deep inelastic μp interactions at 280 GeV
The Bose-Einstein correlation has been observed for pions in deep inelastic μp interactions at 280 GeV. The importance of non-interference correlations in the sample of like charge pion pairs and in the sample used for reference is discussed. The pion emission region is found to be roughly spherical in the pair rest frame with a radius of 0.46-0.84 fm and the chaos factor lambda is 0.60-1.08. (orig.)
Explosion of a collapsing Bose-Einstein condensate
Duine, R. A.; Stoof, H.T.C.
2000-01-01
We show that elastic collisions between atoms in a Bose-Einstein condensate with attractive interactions lead to an explosion that ejects a large fraction of the collapsing condensate. We study variationally the dynamics of this explosion and find excellent agreement with recent experiments on magnetically trapped Rubidium-85. We also determine the energy and angular distribution of the ejected atoms during the collapse.
Vortex dynamics and quantum chaotic trajectories in weakly interacting Bose-Einstein condensation
The dynamics of different vortex clusters in a weakly interacting Bose-Einstein condensate are analytically studied using a variational approach and also by direct numerical calculations. Borrowing the techniques developed in the field of the Bohm's interpretation of quantum mechanics, we define quantum trajectories in the associated quantum superfluid and investigate their chaoticity properties, which are due to the presence of quantum vortices. For a case when a single vortex exists, we find that the onset of chaos is closely related to the geometrical shape of the moving vortex orbits. Moreover, two-body interactions of the condensed atoms play an important role in the occurrence of chaos for vortex pairs in an isotropic trap potential, since this nonlinear interaction destroys the time periodicity of the corresponding velocity field. Finally, in the case of a vortex dipole we discuss the expansion of regular islands caused by the vortex interaction, which leads to the eventual creation and annihilation of vortices. In this case there appear regions where the dynamics are regular embedded in an extended chaotic sea. (authors)
Bose-Einstein correlations in one and two dimensions have been studied, with high statistics, in charged current muon-neutrino interaction events collected with the NOMAD detector at CERN. In one dimension the Bose-Einstein effect has been analyzed with the Goldhaber and the Kopylov-Podgoretskii phenomenological parametrizations. The Goldhaber parametrization gives the radius of the pion emission region RG=1.01±0.05(stat)+0.09-0.06(sys) fm and for the chaoticity parameter the value λ=0.40±0.03(stat)+0.01-0.06(sys). Using the Kopylov-Podgoretskii parametrization yields RKP=2.07±0.04(stat)+0.01-0.14(sys) fm and λKP=0.29±0.06(stat)+0.01-0.04(sys). Different parametrizations of the long-range correlations have been also studied. The two-dimensional shape of the source has been investigated in the longitudinal comoving frame. A significant difference between the transverse and the longitudinal dimensions is observed. The high statistics of the collected sample allowed the study of the Bose-Einstein correlations as a function of rapidity, charged particle multiplicity and hadronic energy. A weak dependence of both radius and chaoticity on multiplicity and hadronic energy is found
Sakmann, Kaspar
2010-07-21
In this thesis, the physics of trapped, interacting Bose-Einstein condensates is analyzed by solving the many-body Schroedinger equation. Particular emphasis is put on coherence, fragmentation and reduced density matrices. First, the ground state of a trapped Bose-Einstein condensate and its correlation functions are obtained. Then the dynamics of a bosonic Josephson junction is investigated by solving the time-dependent many-body Schroedinger equation numerically exactly. These are the first exact results in literature in this context. It is shown that the standard approximations of the field, Gross-Pitaevskii theory and the Bose-Hubbard model fail at weak interaction strength and within their range of expected validity. For stronger interactions the dynamics becomes strongly correlated and a new equilibration phenomenon is discovered. By comparison with exact results it is shown that a symmetry of the Bose- Hubbard model between attractive and repulsive interactions must be considered an artefact of the model. A conceptual innovation of this thesis are time-dependent Wannier functions. Equations of motion for time-dependent Wannier functions are derived from the variational principle. By comparison with exact results it is shown that lattice models can be greatly improved at little computational cost by letting the Wannier functions of a lattice model become time-dependent. (orig.)
In this thesis, the physics of trapped, interacting Bose-Einstein condensates is analyzed by solving the many-body Schroedinger equation. Particular emphasis is put on coherence, fragmentation and reduced density matrices. First, the ground state of a trapped Bose-Einstein condensate and its correlation functions are obtained. Then the dynamics of a bosonic Josephson junction is investigated by solving the time-dependent many-body Schroedinger equation numerically exactly. These are the first exact results in literature in this context. It is shown that the standard approximations of the field, Gross-Pitaevskii theory and the Bose-Hubbard model fail at weak interaction strength and within their range of expected validity. For stronger interactions the dynamics becomes strongly correlated and a new equilibration phenomenon is discovered. By comparison with exact results it is shown that a symmetry of the Bose- Hubbard model between attractive and repulsive interactions must be considered an artefact of the model. A conceptual innovation of this thesis are time-dependent Wannier functions. Equations of motion for time-dependent Wannier functions are derived from the variational principle. By comparison with exact results it is shown that lattice models can be greatly improved at little computational cost by letting the Wannier functions of a lattice model become time-dependent. (orig.)
Bose-Einstein condensation of strongly interacting bosons: From liquid 4He to QCD monopoles
Starting from the classic work of Feynman on the λ point of liquid helium, we show that his idea of universal action per particle at the Bose-Einstein condensation (BEC) transition point is much more robust that it was known before. Using a simple 'moving string model' for supercurrent and calculating the action, both semiclassically and numerically, we show that the critical action is the same for noninteracting and strongly interacting systems such as liquid 4He. Inversely, one can obtain an accurate dependence of critical temperature on density: one important consequence is that high density (solid) He cannot be a BEC state of He atoms, with upper density accurately matching the observations. We then use this model for the deconfinement phase transition of QCD-like gauge theories, treated as BEC of (color-)magnetic monopoles. We start with a Feynman-like approach without interaction, estimating the monopole mass at Tc. Then we include the monopole's Coulomb repulsion, and formulate a relation between the mass, density and coupling which should be fulfilled at the deconfinement point. We end up proposing various ways to test on the lattice whether it is indeed the BEC point for monopoles.
Reservoir interactions of a vortex in a trapped three-dimensional Bose-Einstein condensate
Rooney, S. J.; Allen, A. J.; Zülicke, U.; Proukakis, N. P.; Bradley, A. S.
2016-06-01
We simulate the dissipative evolution of a vortex in a trapped finite-temperature dilute-gas Bose-Einstein condensate using first-principles open-systems theory. Simulations of the complete stochastic projected Gross-Pitaevskii equation for a partially condensed Bose gas containing a single quantum vortex show that the transfer of condensate energy to the incoherent thermal component without population transfer provides an important channel for vortex decay. For the lower temperatures considered, this effect is significantly larger that the population transfer process underpinning the standard theory of vortex decay, and is the dominant determinant of the vortex lifetime. A comparison with the Zaremba-Nikuni-Griffin kinetic (two-fluid) theory further elucidates the role of the particle transfer interaction, and suggests the need for experimental testing of reservoir interaction theory. The dominance of this particular energetic decay mechanism for this open quantum system should be testable with current experimental setups, and its observation would have broad implications for the dynamics of atomic matter waves and experimental studies of dissipative phenomena.
Incoherent scattering of light by a Bose--Einstein condensate of interacting atoms
Mazets, I. E.
2000-01-01
We demonstrate that incoherent photon scattering by a Bose-Einstein condensate of non-ideal atomic gas is enhanced due to bosonic stimulation of spontaneous emission, similarly to coherent scattering in forward direction. Necessary initial population of non-condensate states is provided by quantum depletion of a condensate caused by interatomic repulsion.
宣恒农; 左苗
2011-01-01
We present three families of exact matter-wave soliton solutions for an effective one-dimension two- component Bose-Einstein condensates （BECs） with tunable interactions, harmonic potential and gain or loss term. We investigate the dynamics of bright-bright solitons, bright-dark solitons and dark-dark solitons for the time-dependent expulsive harmonic trap potential, periodically modulated harmonic trap potential, and kinklike modulated harmonic trap potential. Through the Feshbach resonance, these dynamics can be realized in experiments by suitable control of time-dependent trap parameters, atomic interactions, and interaction with thermal cloud.
Bose-Einstein condensates in optical gratings
Full text: Different experiments of atomic physics and quantum optics performed with a Bose Einstein condensate of rubidium atoms are presented. Condensate are dense atomic samples described by a single wave function for the external and internal degrees of freedom. They allow to investigate with high resolution the atomic interaction with electromagnetic fields in different configurations. We have investigated the motion of a condensate within an inhomogeneous magnetic field. If the magnetic field varies slowly enough in space, the effective Hamiltonian governing the dynamics of the slow external variables contains an induced gauge potential, the so-called geometric potential, and in the classical limit geometric forces acting on a neutral particle with a magnetic moment. Our measurements on the motion of a rubidium Bose-Einstein condensate in a time dependent magnetic trap have provided direct evidence for these geometric forces. The properties of Bose-Einstein condensates in lower dimensional trapping potentials have recently attracted increasing interest. 2D condensates can be created in an array of pancake-shaped traps provided by the periodic potential of a 1 D optical lattice. We have investigated Bose-Einstein condensate in an accelerated optical lattice and associated phenomena such as Bloch oscillations and Landau-Zener tunnelling. Furthermore we have investigated the dynamics and phase evolution of Bose-Einstein condensates in 1 D optical lattices. Photoionization of a cold atomic sample offers intriguing possibilities to observe collective effects at extremely low temperatures. Close enough to threshold even the quantum statistics of the products, which are Fermions produced out of quantum degenerate Bosons, may influence the ionization rate itself. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap with laser pulses ionizing through 1-photon and 2-photon absorptions processes has been performed. Losses and the
Dynamics and Matter-Wave Solitons in Bose-Einstein Condensates with Two- and Three-Body Interactions
Jing Chen
2014-01-01
Full Text Available By means of similarity transformation, this paper proposes the matter-wave soliton solutions and dynamics of the variable coefficient cubic-quintic nonlinear Schrödinger equation arising from Bose-Einstein condensates with time-dependent two- and three-body interactions. It is found that, under the effect of time-dependent two- and three-body interaction and harmonic potential with time-dependent frequency, the density of atom condensates will gradually diminish and finally collapse.
Crosta, M.
2012-04-10
We show that the perturbative nonlinearity associated with three-atom interactions, competing with standard two-body repulsive interactions, can change dramatically the evolution of one-dimensional (1D) dispersive shock waves in a Bose-Einstein condensate. In particular, we prove the existence of a rich crossover dynamics, ranging from the formation of multiple shocks regularized by nonlinear oscillations culminating in coexisting dark and antidark matter waves to 1D-soliton collapse. For a given scattering length, all these different regimes can be accessed by varying the density of atoms in the condensate.
Chaotic behavior of three interacting vortices in a confined Bose-Einstein condensate
Kyriakopoulos, Nikos; Koukouloyannis, Vassilis; Skokos, Charalampos; Kevrekidis, Panayotis
2013-01-01
Motivated by recent experimental works, we investigate a system of vortex dynamics in an atomic Bose-Einstein condensate (BEC), consisting of three vortices, two of which have the same charge. These vortices are modeled as a system of point particles which possesses a Hamiltonian structure. This tripole system constitutes a prototypical model of vortices in BECs exhibiting chaos. By using the angular momentum integral of motion we reduce the study of the system to the investigation of a two d...
Astier, Pierre; Baldisseri, Alberto; Baldo-Ceolin, Massimilla; Banner, M; Bassompierre, Gabriel; Benslama, K; Besson, N; Bird, I; Blumenfeld, B; Bobisut, F; Bouchez, J; Boyd, S; Bueno, A G; Bunyatov, S; Camilleri, L L; Cardini, A; Cattaneo, Paolo Walter; Cavasinni, V; Cervera-Villanueva, A; Challis, R C; Chukanov, A; Collazuol, G; Conforto, G; Conta, C; Contalbrigo, M; Cousins, R; Daniels, D; Degaudenzi, H M; Del Prete, T; De Santo, A; Dignan, T; Di Lella, L; do Couto e Silva, E; Dumarchez, J; Ellis, M; Feldman, G J; Ferrari, R; Ferrère, D; Flaminio, Vincenzo; Fraternali, M; Gaillard, J M; Gangler, E; Geiser, A; Geppert, D; Gibin, D; Gninenko, S N; Godley, A; Gómez-Cadenas, J J; Gosset, J; Gössling, C; Gouanère, M; Grant, A; Graziani, G; Guglielmi, A M; Hagner, C; Hernando, J A; Hubbard, D B; Hurst, P; Hyett, N; Iacopini, E; Joseph, C L; Juget, F R; Kent, N; Kirsanov, M M; Klimov, O; Kokkonen, J; Kovzelev, A; Krasnoperov, A V; Lacaprara, S; Lachaud, C; Lakic, B; Lanza, A; La Rotonda, L; Laveder, M; Letessier-Selvon, A A; Lévy, J M; Linssen, Lucie; Ljubicic, A; Long, J; Lupi, A; Lyubushkin, V V; Marchionni, A; Martelli, F; Méchain, X; Mendiburu, J P; Meyer, J P; Mezzetto, Mauro; Mishra, S R; Moorhead, G F; Naumov, D V; Nédélec, P; Nefedov, Yu A; Nguyen-Mau, C; Orestano, D; Pastore, F; Peak, L S; Pennacchio, E; Pessard, H; Petti, R; Placci, A; Polesello, G; Pollmann, D; Polyarush, A Yu; Popov, B; Poulsen, C; Rebuffi, L; Rico, J; Riemann, P; Roda, C; Rubbia, André; Salvatore, F; Schmidt, B; Schmidt, T; Sconza, A; Sevior, M E; Sillou, D; Soler, F J P; Sozzi, G; Steele, D; Stiegler, U; Stipcevic, M; Stolarczyk, T; Tareb-Reyes, M; Taylor, G; Tereshchenko, V V; Toropin, A N; Touchard, A M; Tovey, Stuart N; Tran, M T; Tsesmelis, E; Ulrichs, J; Vacavant, L; Valdata-Nappi, M; Valuev, V Yu; Vannucci, François; Varvell, K E; Veltri, M; Vercesi, V; Vidal-Sitjes, G; Vieira, J M; Vinogradova, T G; Weber, F V; Weisse, T; Wilson, F F; Winton, L J; Yabsley, B D; Zaccone, Henri; Zei, R; Zuber, K; Zuccon, P
2004-01-01
Bose-Einstein Correlations in one and two dimensions have been studied, with high statistics, in charged current muon-neutrino interaction events collected with the NOMAD detector at CERN. In one dimension the Bose-Einstein effect has been analyzed with the Goldhaber and the Kopylov-Podgoretskii phenomenological parametrizations. The Goldhaber parametrization gives the radius of the pion emission region R_G = 1.01+/-0.05(stat)+0.09-0.06(sys) fm and for the chaoticity parameter the value lambda = 0.40+/-0.03(stat)+0.01-0.06(sys). Using the Kopylov-Podgoretskii parametrization yields R_KP = 2.07+/-0.04(stat)+0.01-0.14(sys) fm and lambda_KP = 0.29+/-0.06(stat)+0.01-0.04(sys). Different parametrizations of the long-range correlations have been also studied. The two-dimensional shape of the source has been investigated in the longitudinal co-moving frame. A significant difference between the transverse and the longitudinal dimensions is observed. The high statistics of the collected sample allowed the study of the...
Phenomenological theory of spinor Bose-Einstein condensates
Gu, Qiang
2002-01-01
A phenomenological model is proposed to describe the behavior of spinor Bose-Einstein condensates. In the absence of hyperfine spin-spin interactions, Bose-Einstein condensation leads to a spontaneous magnetization at the same transition temperature. This is the so-called Bose-Einstein ferromagnetism. Including the hyperfine spin interactions, the phase diagram of the spinor condensate in an optical trap is studied and the Gross-Pitaevskii equation is extended. The possibility of checking for...
Phonon-polaritons in Bose-Einstein condensates induced by Casimir-Polder interaction with graphene
Terças, H; Ribeiro, S.; Mendonça, J. T.
2014-01-01
We consider the mechanical coupling between a two-dimensional Bose-Einstein condensate with a graphene sheet via the vacuum fluctuations of the electromagnetic field which are at the origin of the so-called Casimir-Polder potential. By deriving a self-consistent set of equations governing the dynamics of the condensate and the flexural (out-of-plane) modes of the graphene, we can show the formation of a new type of purely acoustic quasi-particle excitation, a phonon-polariton resulting from t...
Chavanis, Pierre-Henri
2016-01-01
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.
Quasi-polaritons in Bose-Einstein condensates induced by Casimir-Polder interaction with graphene.
Terças, H; Ribeiro, S; Mendonça, J T
2015-06-01
We consider the mechanical coupling between a two-dimensional Bose-Einstein condensate and a graphene sheet via the vacuum fluctuations of the electromagnetic field which are at the origin of the so-called Casimir-Polder potential. By deriving a self-consistent set of equations governing the dynamics of the condensate and the flexural (out-of-plane) modes of the graphene, we can show the formation of a new type of purely acoustic quasi-particle excitation, a quasi-polariton resulting from the coherent superposition of quanta of flexural and Bogoliubov modes. PMID:25966318
This paper studies the regular and chaotic spatial distribution of Bose-Einstein condensed atoms with a space-dependent nonlinear interaction. There exists a steady atomic current in the system due to the space-dependent phase of condensate. For the system with a positive chemical potential and repulsive interatomic interaction, we construct the general solution of the 1st-order equation, whose boundedness conditions contain the famous Mel'nikov chaotic criterion. When the system doesn't satisfy the perturbation conditions, numerical simulations reveal that increasing the atomic current can destroy the spatial symmetry of the distributional structure of condensed atoms, whether the condensed atoms in a chaotic or regular distribution. (authors)
Chaotic behavior of three interacting vortices in a confined Bose-Einstein condensate
Kyriakopoulos, Nikos [SUPA, Department of Physics and Institute for Complex Systems and Mathematical Biology, King' s College, University of Aberdeen, Aberdeen AB24 3UE (United Kingdom); Koukouloyannis, Vassilis [Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Skokos, Charalampos [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701 (South Africa); Physics Department, Aristotle University of Thessaloniki, GR-54124 Thessaloniki (Greece); Kevrekidis, Panayotis G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-9305 (United States)
2014-06-01
Motivated by recent experimental works, we investigate a system of vortex dynamics in an atomic Bose-Einstein condensate (BEC), consisting of three vortices, two of which have the same charge. These vortices are modeled as a system of point particles which possesses a Hamiltonian structure. This tripole system constitutes a prototypical model of vortices in BECs exhibiting chaos. By using the angular momentum integral of motion, we reduce the study of the system to the investigation of a two degree of freedom Hamiltonian model and acquire quantitative results about its chaotic behavior. Our investigation tool is the construction of scan maps by using the Smaller ALignment Index as a chaos indicator. Applying this approach to a large number of initial conditions, we manage to accurately and efficiently measure the extent of chaos in the model and its dependence on physically important parameters like the energy and the angular momentum of the system.
Creation of ^{39}K Bose-Einstein condensates with tunable interaction
Winter, Nils
2013-01-01
The capability of producing ultracold atomic gases has had considerable impact on the field of quantum physics. Due to their purity and tolerance against external perturbation these ensembles are an ideal instrument for precision experiments in atomic and molecular physics. The ability to create...... Bose-Einstein condensates and thus accumulate ultracold atoms in a single quantum state enables the construction of model systems which can be precisely controlled. That allows a deeper understanding of complicated quantum systems. Ultracold atoms in optical lattices are an excellent example, since...... they provide regular lattices that are used as a quantum simulator of solid state systems. In particular the Mott-insulator phase and Cooper paring of fermions could be observed in these ultracold systems. Furthermore the scattering properties of some atomic gases can be tuned to a great extend. This...
Chaotic behavior of three interacting vortices in a confined Bose-Einstein condensate
Motivated by recent experimental works, we investigate a system of vortex dynamics in an atomic Bose-Einstein condensate (BEC), consisting of three vortices, two of which have the same charge. These vortices are modeled as a system of point particles which possesses a Hamiltonian structure. This tripole system constitutes a prototypical model of vortices in BECs exhibiting chaos. By using the angular momentum integral of motion, we reduce the study of the system to the investigation of a two degree of freedom Hamiltonian model and acquire quantitative results about its chaotic behavior. Our investigation tool is the construction of scan maps by using the Smaller ALignment Index as a chaos indicator. Applying this approach to a large number of initial conditions, we manage to accurately and efficiently measure the extent of chaos in the model and its dependence on physically important parameters like the energy and the angular momentum of the system
Two quite different but interconnected topics are covered: the Bose-Einstein effect in two-jet events at LEP, i.e. events with a single string structure, and a new test on hydrodynamical models. In this test the interferometrical correlator plays a key role and can be used to bring information on the matter evolution in time and space. A preliminary DELPHI analysis has however shown that the extraction of the two-particle correlation function is contaminated by large systematic uncertainties. Three different analysis, all using standard methods, give inconsistent results. Furthermore the two-particle correlation itself is shown to be due not only to Bose-Einstein correlations but also to the decay of heavy quark resonances, so the determination of the Bose-Einstein effect depends on the modelling of these other sources. This modelling is at the moment not accurate enough. More work is needed to clarify the situation. (author) 25 refs.; 16 figs.; 1 tab
The notion of Bose-Einstein condensation (BEC) is introduced in the simple case of a perfect gas of bosons. We show the existence of a singularity that was discovered by Einstein and that appears when the density in the phase space is above a critical value. A few years after the discovery of BEC in several gases, it is interesting to look back at some properties of superfluid helium, the author comments shortly on boiling and evaporation, then on the role of rotons and vortices in the existence of a critical velocity in superfluid helium. The author discusses also the existence of a condensate in a liquid with strong interactions and the pressure variation of its superfluid transition temperature. The discovery of BEC in dilute gases of Rb, Na and Li in magnetic traps has stimulated an enormous revival of the interest in macroscopic quantum behavior of dilute gas at low temperature. Experiments with trapped Bose condensed gases have revealed profound condensed matter behavior of these extremely dilute systems. The author describes the key features of this behavior and discusses theoretical approaches that are being used in the field of quantum gases. Methods of production and of detection of a BEC in gaseous phases are presented, the issue of the cooling of fermion gases and of Boson-fermions mixing is discussed. (A.C.)
Many-body dynamics of a Bose--Einstein condensate collapsing by quantum tunneling
Saito, Hiroki
2013-01-01
The dynamics of a Bose-Einstein condensate of atoms having attractive interactions is studied using quantum many-body simulations. The collapse of the condensate by quantum tunneling is numerically demonstrated and the tunneling rate is calculated. The correlation properties of the quantum many-body state are investigated.
We observed the spin texture formation and the spatial modulation of the longitudinal magnetization in a spin-2 87Rb Bose-Einstein condensate. The observed results are compared with numerical simulations of the Gross-Pitaevskii equation, which are the effects due to the magnetic dipole-dipole interaction. These results show that the magnetic dipole-dipole interaction has significant effects even on spinor condensates of alkali metal atoms. (author)
Soliton resonance in bose-einstein condensate
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.
The model of double-well Bose-Einstein condensates in the strong-interaction regime is shown to reduce adiabatically to an effective two-state model describing the Rabi oscillations between the two atomic Fock states |N, 0> and |0, N>, and the NOON states of arbitrary ultracold atoms can therefore be generated periodically from the initial state of either one of the Fock states. (general)
Sun, Kuei; Qu, Chunlei; Xu, Yong; Zhang, Yongping; Zhang, Chuanwei
Spin-orbit (SO) coupling plays a major role in many important phenomena in condensed matter physics. However, the SO coupling physics in high-spin systems, especially with superfluids, has not been well explored because of the spin half of electrons in solids. In this context, the recent experimental realization of spin-orbit coupling in spin-1 Bose-Einstein condensates (BECs) has opened a completely new avenue for exploring SO-coupled high-spin superfluids. Nevertheless, the experiment has only revealed the single-particle physics of the system. Here, we study the effects of interactions between atoms on the ground states and collective excitations of SO-coupled spin-1 BECs in the presence of a spin-tensor potential. We find that ferromagnetic interaction between atoms can induce a stripe phase exhibiting two modulating patterns. We characterize the phase transitions between different phases using the spin-tensor density as well as the collective dipole motion of the BEC. We show that there exists a new type of double maxon-roton structure in the Bogoliubov-excitation spectrum, attributing to the three band minima of the SO-coupled spin-1 BEC. Our work could motivate further theoretical and experimental study along this direction.
Kozlov, M G; Budker, D
2009-01-01
Two-photon transitions between atomic states of total electronic angular momentum $J_a=0$ and $J_b=1$ are forbidden when the photons are of the same energy. This selection rule is analogous to the Landau-Yang theorem in particle physics that forbids decays of vector particle into two photons. It arises because it is impossible to construct a total angular momentum $J_{2\\gamma}=1$ quantum-mechanical state of two photons that is permutation symmetric, as required by Bose-Einstein statistics. In atoms with non-zero nuclear spin, the selection rule can be violated due to hyperfine interactions. Two distinct mechanisms responsible for the hyperfine-induced two-photon transitions are identified, and the hyperfine structure of the induced transitions is evaluated. The selection rule is also relaxed, even for zero-nuclear-spin atoms, by application of an external magnetic field. Once again, there are two similar mechanisms at play: Zeeman splitting of the intermediate-state sublevels, and off-diagonal mixing of state...
Soliton Solutions in Three-Component Bose-Einstein Condensates
ZHANG Xiao-Fei; XIE Chong-Wei; WANG Shi-En
2007-01-01
We obtain soliton and plane wave solutions for the coupled nonlinear Schr(o)dinger equations, which describe the dynamics of the three-component Bose-Einstein condensates by using the Hirota method. Meanwhile we find that the system which has attractive atomic interaction will only possess a shape changing (inelastic) collision property due to intensity redistribution in the absence of the spin-exchange interaction. As a discussed example, we investigate the one-soliton, two-soliton solutions and collisional effects between bright two-soliotn solution, which lead to the intensity redistribution.
New results on the Bose-Einstein effect in e+e- interactions or the GGLP effect revisited
Experimental data on the Bose-Einstein (B.E.) enhancement of pion pairs from e+e- colliders is reviewed. The data comes from CLEO, Mark II, and TASSO. A result on KK enhancement from the Axial Field Spectrometer (AFS) is also quoted. Results of new derivations based on the string or Lund model of the inside outside cascade are also discussed
Topological Objects in Two-component Bose-Einstein Condensates
Cho, Y. M.; Khim, Hyojoong; Zhang, Pengming
2005-01-01
We study the topological objects in two-component Bose-Einstein condensates. We compare two competing theories of two-component Bose-Einstein condensate, the popular Gross-Pitaevskii theory and the recently proposed gauge theory of two-component Bose-Einstein condensate which has an induced vorticity interaction. We show that two theories produce very similar topological objects, in spite of the obvious differences in dynamics. Furthermore we show that the gauge theory of two-component Bose-E...
Production of a chromium Bose-Einstein condensate
Griesmaier, Axel; Stuhler, Jürgen; Pfau, Tilman
2005-01-01
The recent achievement of Bose-Einstein condensation of chromium atoms [1] has opened longed-for experimental access to a degenerate quantum gas with long-range and anisotropic interaction. Due to the large magnetic moment of chromium atoms of 6 {$\\mu$}B, in contrast to other Bose- Einstein condensates (BECs), magnetic dipole-dipole interaction plays an important role in a chromium BEC. Many new physical properties of degenerate gases arising from these magnetic forces have been predicted in ...
Etienne Wamba; Timoléon C. Kofané; Alidou Mohamadou
2012-01-01
We construct,through a further extension of the tanh-function method,the matter-wave solutions of Bose-Einstein condensates (BECs) with a three-body interaction.The BECs are trapped in a potential comprising the linear magnetic and the time-dependent laser fields.The exact solutions obtained include soliton solutions,such as kink and antikink as well as bright,dark,multisolitonic modulated waves.We realize that the motion and the shape of the solitary wave can be manipulated by controlling the strengths of the fields.
Kulchitsky, Yuri
2016-07-01
The report on the recent results of soft-QCD with the ATLAS experiment at the LHC is presented. The effect of space-time geometry in the hadronization phase has been studied in the context of Bose-Einstein correlations between charged particles, for determining the size and shape of the source from which particles are emitted. Bose-Einstein correlation parameters are investigated in proton-proton collisions at 0.9 and 7 TeV, up to very high charged particle multiplicities. Measurements of the properties of charged particle production are presented from proton-proton collisions at different centre-of-mass energies in the range of 0.9 to 13 TeV and compared to various Monte Carlo event generator models. Furthermore, particle distributions sensitive to the underlying event have been measured and are compared to theoretical models. The production properties of mesons and baryons are presented and compared to predictions.
Adiabatic transport of Bose-Einstein condensate in double-well trap
Nesterenko, V. O.; A.N. Novikov; Cherny, A. Yu.; Cruz, F. F. de Souza; Suraud, E.
2009-01-01
A complete irreversible adiabatic transport of Bose-Einstein condensate (BEC) in a double-well trap is investigated within the mean field approximation. The transfer is driven by time-dependent (Gaussian) coupling between the wells and their relative detuning. The protocol successfully works in a wide range of both repulsive and attractive BEC interaction. The nonlinear effects caused by the interaction can be turned from detrimental into favorable for the transport. The results are compared ...
Hysteresis effects in Bose-Einstein condensates
Sacchetti, Andrea
2010-01-01
Here, we consider damped two-components Bose-Einstein condensates with many-body interactions. We show that, when the external trapping potential has a double-well shape and when the nonlinear coupling factors are modulated in time, hysteresis effects may appear under some circumstances. Such hysteresis phenomena are a result of the joint contribution between the appearance of saddle node bifurcations and damping effect.
Cosmic Axion Bose-Einstein Condensation
Banik, Nilanjan; Sikivie, Pierre
2015-01-01
QCD axions are a well-motivated candidate for cold dark matter. Cold axions are produced in the early universe by vacuum realignment, axion string decay and axion domain wall decay. We show that cold axions thermalize via their gravitational self-interactions, and form a Bose-Einstein condensate. As a result, axion dark matter behaves differently from the other proposed forms of dark matter. The differences are observable.
Zhang, Xiao-Fei; Hu, Xing-Hua; Liu, Xun-Xu; Liu, W. M.
2009-03-01
We present a family of exact vector-soliton solutions for the coupled nonlinear Schrödinger equations with tunable interactions and harmonic potential, and then apply the model to investigate the dynamics of solitons and collisions between two orthogonal solitons in the case with equal interaction parameters. Our results show that the exact vector-soliton solutions can be obtained with arbitrary tunable interactions as long as a proper harmonic potential is applied. The dynamics of solitons can be controlled by the Feshbach resonance and the collisions are essentially elastic and do not depend on the initial conditions.
Quantum Dynamics with Spatiotemporal Control of Interactions in a Stable Bose-Einstein Condensate.
Clark, Logan W; Ha, Li-Chung; Xu, Chen-Yu; Chin, Cheng
2015-10-01
Optical control of atomic interactions in quantum gases is a long-sought goal of cold atom research. Previous experiments have been hindered by rapid decay of the quantum gas and parasitic deformation of the trap potential. We develop and implement a generic scheme for optical control of Feshbach resonances which yields long quantum gas lifetimes and a negligible parasitic dipole force. We show that fast and local control of interactions leads to intriguing quantum dynamics in new regimes, highlighted by the formation of van der Waals molecules and localized collapse of a Bose condensate. PMID:26550731
Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices
GU Huai-Qiang; WANG Zhi-Cheng; JIN Kang; TAN Lei
2006-01-01
@@ We study the Bloch oscillations of two-component Bose-Einstein condensates trapped in spin-dependent optical lattices. The influence of the intercomponent atom interaction on the system is discussed in detail Accelerated breakdown of the Bloch oscillations and revival phenomena are found respectively for the repulsive and attractive case. For both the cases, the system will finally be set in a quantum self-trapping state due to dynamical instability.
We derive exact thermodynamic identities relating the average number of condensed atoms and the root-mean-square fluctuations determined in different statistical ensembles for the weakly interacting Bose gas confined in a box. This is achieved by introducing the concept of auxiliary partition functions for model Hamiltonians that do conserve the total number of particles. Exploiting such thermodynamic identities, we provide the first, completely analytical prediction of the microcanonical particle number fluctuations in the weakly interacting Bose gas. Such fluctuations, as a function of the volume V of the box are found to behave normally, in contrast with the anomalous scaling behaviour V4/3 of the fluctuations in the ideal Bose gas. (author). Letter-to-the-editor
Illuminati, Fabrizio [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany); Dipartimento di Fisica, Universita di Salerno, and INFM, Unita di Salerno, I-84081 Baronissi SA (Italy); Navez, Patrick [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany); Institute of Materials Science, Demokritos NCSR, POB 60228, 15310 Athens (Greece); Wilkens, Martin [Institut fuer Physik, Universitaet Potsdam, Am Neuen Palais 10, D-14415, Potsdam (Germany)
1999-08-14
We derive exact thermodynamic identities relating the average number of condensed atoms and the root-mean-square fluctuations determined in different statistical ensembles for the weakly interacting Bose gas confined in a box. This is achieved by introducing the concept of auxiliary partition functions for model Hamiltonians that do conserve the total number of particles. Exploiting such thermodynamic identities, we provide the first, completely analytical prediction of the microcanonical particle number fluctuations in the weakly interacting Bose gas. Such fluctuations, as a function of the volume V of the box are found to behave normally, in contrast with the anomalous scaling behaviour V{sup 4/3} of the fluctuations in the ideal Bose gas. (author). Letter-to-the-editor.
Illuminati, Fabrizio; Navez, Patrick; Wilkens, Martin
1999-01-01
We derive exact thermodynamic identities relating the average number of condensed atoms and the root-mean-square fluctuations determined in different statistical ensembles for the weakly interacting Bose gas confined in a box. This is achieved by introducing the concept of {\\it auxiliary partition functions} for model Hamiltonians that do conserve the total number of particles. Exploiting such thermodynamic identities, we provide the first, completely analytical prediction of the microcanonic...
Bose-Einstein condensation in a one-dimensional system of interacting bosons
Tomchenko, Maksim
2016-01-01
Using the Vakarchuk formulae for the density matrix, we calculate the number N_k of atoms with momentum \\hbar k for the ground state of a uniform one-dimensional periodic system of interacting bosons. We obtain for impenetrable point bosons N_0 = 2\\sqrt{N} and N_{k=2\\pi j/L} = 0.31N_{0}/\\sqrt{|j|}. That is, there is no condensate or quasicondensate on low levels at large N. For almost point bosons with weak coupling (\\beta=\\frac{\
Dynamics of Bose-Einstein condensation
Davis, M J
2001-01-01
approaches are in excellent agreement in their range of validity. We are therefore able to assign a temperature to the numerical simulations. However, the presently available equilibrium theories fail near the critical region, whereas the projected Gross-Pitaevskii equation remains valid throughout the Bose-Einstein condensation phase transition as long as the relevant modes remain highly occupied. This suggests that the equation will be useful in studying the role of vortices in the critical region, and the shift of the transition temperature with the atomic interaction strength. This thesis is concerned with the dynamics of thermal Bose-Einstein condensates with two main areas of emphasis. We summarise the development of the quantum kinetic theory of C. W. Gardiner, P. Zoller, and co-workers, and in particular its application to the problem of condensate growth. We extend an earlier model of the growth of a Bose-Einstein condensate to include the full dynamical effects of the thermal cloud by numerically so...
Mean-field description of collapsing and exploding Bose-Einstein condensates
We perform numerical simulations based on the time-dependent mean-field Gross-Pitaevskii equation to understand some aspects of a recent experiment by Donley et al. [Nature (London) 412, 295 (2001)] on the dynamics of collapsing and exploding Bose-Einstein condensates of 85Rb atoms. These authors manipulated the atomic interaction by an external magnetic field via a Feshbach resonance, thus changing the repulsive condensate into an attractive one, and vice versa. In the actual experiment they suddenly changed the scattering length of atomic interaction from a positive to a large negative value on a preformed condensate in an axially symmetric trap. Consequently, the condensate collapsed and ejected atoms via explosion. We find that the present mean-field analysis can explain some aspects of the dynamics of the collapsing and exploding Bose-Einstein condensates
We study the virial relations for ultracold trapped two-component Fermi gases in the case of short finite range interactions. Numerical verifications for such relations are reported through the Bardeen-Cooper-Schrieffer (BCS) Bose-Einstein-condensate (BEC) crossover. As an intermediate step, it is necessary to evaluate the partial derivatives of the many-body energy with respect to the inverse of the scattering length and with respect to the interaction range. Once the binding energy of the formed molecules in the BEC side is subtracted, the corresponding energy derivatives are found to have extreme values at the unitary limit. The value of the derivative with respect to the potential range in that limit is large enough to yield measurable differences between the total energy and twice the trapping energy unless the interacting system is described by extremely short potential ranges. The virial results are used to check the quality of the variational wavefunction involved in the calculations.
Rosales-Zarate, L E C; Jauregui, R, E-mail: laura@fisica.unam.m, E-mail: rocio@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, Mexico DF 01000 (Mexico)
2010-04-15
We study the virial relations for ultracold trapped two-component Fermi gases in the case of short finite range interactions. Numerical verifications for such relations are reported through the Bardeen-Cooper-Schrieffer (BCS) Bose-Einstein-condensate (BEC) crossover. As an intermediate step, it is necessary to evaluate the partial derivatives of the many-body energy with respect to the inverse of the scattering length and with respect to the interaction range. Once the binding energy of the formed molecules in the BEC side is subtracted, the corresponding energy derivatives are found to have extreme values at the unitary limit. The value of the derivative with respect to the potential range in that limit is large enough to yield measurable differences between the total energy and twice the trapping energy unless the interacting system is described by extremely short potential ranges. The virial results are used to check the quality of the variational wavefunction involved in the calculations.
Wamba, E; Sabari, S; Porsezian, K; Mohamadou, A; Kofané, T C
2014-05-01
We investigate the dynamical instability of Bose-Einstein condensates (BECs) with higher-order interactions immersed in an optical lattice with weak driving harmonic potential. For this, we compute both analytically and numerically a modified Gross-Pitaevskii equation with higher-order nonlinearity and external potentials generated by magnetic and optical fields. Using the time-dependent variational approach, we derive the ordinary differential equations for the time evolution of the amplitude and phase of modulational perturbation. Through an effective potential, we obtain the modulational instability condition of BECs and discuss the effect of the higher-order interaction in the dynamics of the condensates in presence of optical potential. We perform direct numerical simulations to support our analytical results, and good agreement is found. PMID:25353871
Bose-Einstein condensation of indirect excitons in coupled quantum wells
Kavoulakis, G. M.
2002-01-01
We study the ground-state properties of a quasi-two-dimensional Bose-Einstein condensate of indirect excitons, which are confined in an anisotropic harmonic potential. Incorporating the interactions, we calculate the order parameter variationally. The difficulties in the detection of a Bose-Einstein condensate are also discussed, along with possible ways which would overcome them.
Quantum turbulence in atomic Bose-Einstein condensates
Weakly interacting, dilute atomic Bose-Einstein condensates (BECs) have proved to be an attractive context for the study of nonlinear dynamics and quantum effects at the macroscopic scale. Recently, weakly interacting, dilute atomic BECs have been used to investigate quantum turbulence both experimentally and theoretically, stimulated largely by the high degree of control which is available within these quantum gases. In this article we motivate the use of weakly interacting, dilute atomic BECs for the study of turbulence, discuss the characteristic regimes of turbulence which are accessible, and briefly review some selected investigations of quantum turbulence and recent results. We focus on three stages of turbulence – the generation of turbulence, its steady state and its decay – and highlight some fundamental questions regarding our understanding in each of these regimes
Vortex dynamics in coherently coupled Bose-Einstein condensates
Calderaro, Luca; Massignan, Pietro; Wittek, Peter
2016-01-01
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 ...
Approaching Bose-Einstein Condensation
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…
Q-balls in atomic Bose-Einstein condensates
Enqvist, K
2003-01-01
Relativistic scalar field theories with a conserved global charge Q often possess (meta)stable spherically symmetric soliton solutions, called Q-balls. We elaborate on the perfect formal analogy which exists between Q-balls, and spherically symmetric solitons in certain non-relativistic atomic Bose-Einstein condensates, for which the dominant interatomic interaction can be tuned attractive. The stability of such atomic Q-balls depends on higher-order interatomic interactions, which can render the Q-balls absolutely stable for large Q. In a harmonic trap, present in existing experiments, the Q-ball solution is modified in an essential way. If the trap is significantly prolongated in one direction, however, then genuine solitons do appear, and some of the Q-ball properties studied in a relativistic cosmological context, such as their formation and collisions, can also be addressed experimentally.
Rydberg Electrons in a Bose-Einstein Condensate.
Wang, Jia; Gacesa, Marko; Côté, R
2015-06-19
We investigate a hybrid system composed of ultracold Rydberg atoms immersed in an atomic Bose-Einstein condensate (BEC). The coupling between Rydberg electrons and BEC atoms leads to excitations of phonons, the exchange of which induces a Yukawa interaction between Rydberg atoms. Because of the small electron mass, the effective charge associated with this quasiparticle-mediated interaction can be large. Its range, equal to the BEC healing length, is tunable using Feshbach resonances to adjust the scattering length between BEC atoms. We find that for small healing lengths, the distortion of the BEC can "image" the Rydberg electron wave function, while for large healing lengths the induced attractive Yukawa potentials between Rydberg atoms are strong enough to bind them. PMID:26196974
Bose-Einstein condensates in atomic gases: simple theoretical results
The author presents the theory of the Bose-Einstein condensation along with a discussion of experimental tests. The author deals successively with the following topics: - the ideal Bose gas in a trap (first in a harmonic trap and then in a more general trap), - a model for the atomic interaction, - interacting Bose gas in the Hartree-Fock approximation, - properties of the condensate wavefunction, - the Gross-Pitaevskii equation, - Bogoliubov approach and thermodynamical stability, - phase coherence properties at the Bose-Einstein condensate, and - symmetry-breaking description of condensates. (A.C.)
Quantum field theory and Bose Einstein condensation
We study the phenomenon of Bose-Einstein condensation in cosmological and laboratory situations. To do this we examine the extreme temperature limits of a self-interacting O(2)-invariant scalar field theory with a non-zero charge density. The transition point has been well known for a long time in the case of an interactionless theory. However, due to a combination of technical problems imposed by having interactions and finite density, the transition in the interacting theory is not well understood. Here, in order to probe the Bose-Einstein condensation transition we perform a dimensional reduction of the 4D O(2)-invariant theory to give an effective theory in 3D. After dimensional reduction we use the 3D effective theory to calculate the two-loop effective potential which is used to examine the phase structure. This is a perturbative calculation and is still inappropriate for looking at the critical temperature. To find the critical temperature we use the non-perturbative linear delta expansion on the effective 3D theory. Tins is done in both the high temperature limit appropriate to cosmological applications and the low temperature limit appropriate to laboratory experiments with atomic gases. We study the Bose-Einstein condensation transition out of equilibrium. After a sudden quench which sends the system into the critical region, we look at how the condensate originates and grows. We study the equations of motion obtained from the one-loop effective action. It is found that the magnitude of the field expectation value grows at a slower rate at higher charge densities but that charge flows into the ground state at a faster rate at higher charge densities. In order to perform most of the analytic calculations, we show how dimensional regularization and Mellin summation can be elegantly combined to give an economical method for calculating high temperature Feynman diagrams. (author)
Entanglement Properties in Two-Component Bose-Einstein Condensate
Jiang, Di-You
2016-05-01
We investigate entanglement inseparability and bipartite entanglement of in two-component Bose-Einstein condensate in the presence of the nonlinear interatomic interaction, interspecies interaction. Entanglement inseparability and bipartite entanglement have the similar properties. More entanglement can be generated by adjusting the nonlinear interatomic interaction and control the time interval of the entanglement by adjusting interspecies interaction.
Two scales in Bose-Einstein correlations
Khoze, V A; Ryskin, M G; Schegelsky, V A
2016-01-01
We argue that the secondaries produced in high energy hadron collisions are emitted by small size sources distributed over a much larger area in impact parameter space occupied by the interaction amplitude. That is, Bose-Einstein correlation of two emitted identical particles should be described by a `two-radii' parametrization ansatz. We discuss the expected energy, charged multiplicity and transverse momentum of the pair (that is, $\\sqrt{s},~N_{\\rm ch}, k_t$) behaviour of both the small and large size components.
Self-consistent effects of continuous wave output coupling of atoms from a Bose-Einstein condensate
Hutchinson, D. A. W.
1998-01-01
We present a self-consistent mean field model of the extraction of atoms from a Bose-Einstein condensate to form a CW atom laser. The model is based upon the Hartree-Fock Bogoliubov equations within the Popov approximation, modified by the inclusion of spatially dependent source and sink terms, which lead to current flow within the condensate. The effects of this current flow are investigated for traps containing Rubidium (repulsive effective interaction) and Lithium (attractive interaction) ...
Dark Lump Excitations in Bose-Einstein Condensates
黄国翔; 朱善华
2002-01-01
Key Laboratory for Optical and Magnetic Resonance Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062We investigate the dynamics of two-dimensional matter-wave pulses in a Bose-Einstein condensate with diskshaped traps. For the case ofrepulsive atom-atom interactions, a Kadomtsev-Petviashvili equation with positive dispersion is derived using the method of multiple scales. The results show that it is possible to excite dark lump-like two-dimensional nonlinear excitations in the Bose-Einstein condensate.
Generalized Bose-Einstein Condensation
Mullin, William J.; Sakhel, Asaad R.
2012-02-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We review examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically occupied. We begin by discussing Type I or "normal" BEC into a single state for an isotropic harmonic oscillator potential. Other geometries and external potentials are then considered: the "channel" potential (harmonic in one dimension and hard-wall in the other), which displays Type II, the "cigar trap" (anisotropic harmonic potential), and the "Casimir prism" (an elongated box), the latter two having Type III condensations. General box geometries are considered in an appendix. We particularly focus on the cigar trap, which Van Druten and Ketterle first showed had a two-step condensation: a GBEC into a band of states at a temperature T c and another "one-dimensional" transition at a lower temperature T 1 into the ground state. In a thermodynamic limit in which the ratio of the dimensions of the anisotropic harmonic trap is kept fixed, T 1 merges with the upper transition, which then becomes a normal BEC. However, in the thermodynamic limit of Beau and Zagrebnov, in which the ratio of the boundary lengths increases exponentially, T 1 becomes fixed at the temperature of a true Type I phase transition. The effects of interactions on GBEC are discussed and we show that there is evidence that Type III condensation may have been observed in the cigar trap.
Discrete Bose-Einstein spectra
The Bose-Einstein energy spectrum of a quantum gas, confined in a rigid cubic box, is shown to become discrete and strongly dependent on the box geometry (size L), temperature, T and atomic mass number, Aat, in the region of small γ=AatTV1/3. This behavior is the consequence of the random state degeneracy in the box. Furthermore, we demonstrate that the total energy does not obey the conventional law any longer, but a new law, which depends on γ and on the quantum gas fugacity. This energy law imposes a faster decrease to zero than it is classically expected, for γ→0. The lighter the gas atoms, the higher the temperatures or the box size, for the same effects in the discrete Bose-Einstein regime. (author)
Quantum field theory and Bose Einstein condensation
Bedingham, D J
2001-01-01
We study the phenomenon of Bose-Einstein condensation in cosmological and laboratory situations. To do this we examine the extreme temperature limits of a self-interacting O(2)-invariant scalar field theory with a non-zero charge density. The transition point has been well known for a long time in the case of an interactionless theory. However, due to a combination of technical problems imposed by having interactions and finite density, the transition in the interacting theory is not well understood. Here, in order to probe the Bose-Einstein condensation transition we perform a dimensional reduction of the 4D O(2)-invariant theory to give an effective theory in 3D. After dimensional reduction we use the 3D effective theory to calculate the two-loop effective potential which is used to examine the phase structure. This is a perturbative calculation and is still inappropriate for looking at the critical temperature. To find the critical temperature we use the non-perturbative linear delta expansion on the effec...
This thesis describes a number of aspects of multiparticle production in π+p, K+p and pp collisions at an incident beam momentum of 250 GeV/c. The corresponding centre of mass energy is 21.7 GeV. The experimental data have been collected with the European Hybrid Spectrometer at CERN. The experimental set-up and data processing chain are described in chapter 2. Chapter 3 concerns the methods used for the charged particle identification in the experiment. The analysis of the properties of the particle collisions starts in chapter 4. Here, a study of the multiplicity distribution in phase space intervals is presented. This analysis is done for the non-single-diffractive π+p and pp collisions. In general the data can be well described by negative binomial distributions. This holds in particular for central regions of rapidity. However, also indication is seen for the existence of correlations in the data beyond those already absorbed into negative binomials. It is shown that the interpretation of the negative binominal distribution in terms of a cascading rather than the stimulated emission mechanism is favoured. The data are, furthermore, compared with results at other energies and another type of collision. As a consequence of the requirement of a symmetric wave function for identical pions, the probability for two identical pions to be close in phase space is enhanced compared to what is expected for non-identical particles under the same conditions. These Bose-Einstein correlations are studied in chapter 5 for the combined π+p and K+p sample. In particular, the interference effect has been studied with different reference samples and with different parametrisations of the effect. 108 refs.; 57 figs.; 23 tabs
Generalized Bose-Einstein Condensation
Mullin, William J.; Sakhel, Asaad R.
2010-01-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We review examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically...
We present a double-mapping method (D-MM), a natural combination of a similarity with F-expansion methods, for obtaining general solvable nonlinear evolution equations. We focus on variable-coefficients complex Ginzburg-Landau equations (VCCGLE) with multi-body interactions. We show that it is easy by this method to find a large class of exact solutions of Gross-Pitaevskii and Gross-Pitaevskii-Ginzburg equations. We apply the D-MM to investigate the dynamics of Bose-Einstein condensation with two- and three-body interactions. As a surprising result, we obtained that it is very easy to use the built D-MM to obtain a large class of exact solutions of VCCGLE with two-body interactions via a generalized VCCGLE with two- and three-body interactions containing cubic-derivative terms. The results show that the proposed method is direct, concise, elementary, and effective, and can be a very effective and powerful mathematical tool for solving many other nonlinear evolution equations in physics.
Investigating tunable KRb gases and Bose-Einstein condensates
Jørgensen, Nils Byg
2015-01-01
We present the production of dual-species Bose-Einstein condensates of 39K and 87Rb with tunable interactions. A dark spontaneous force optical trap was used for 87Rb to reduce the losses in 39K originating from light-assisted collisions in the magneto optical trapping phase. Using sympathetic...
Gotsman, E; Maor, U
2016-01-01
In the framework of our model of soft interactions at high energy based on CGC/saturation approach,we show that Bose-Einstein correlations of identical gluons lead to large values of $v_n$. We demonstrate how three dimensional scales of high energy interactions: hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of $v_n$. Our calculation shows that the structure of the `dressed' Pomeron leads to values of $v_n$ which are close to experimental values for proton-proton scattering, 20\\% smaller than the observed values for proton-lead collisions, and close to lead-lead collisions for 0-10\\% centrality. Bearing this result in mind, we conclude that it is premature to consider, that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark-gluon plasma.
Tunneling Dynamics Between Atomic and Molecular Bose-Einstein Condensates
CHEN Chang-Yong
2004-01-01
Tunneling dynamics of multi-atomic molecules between atomic and multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated.It is indicated that the tunneling in the two Bose-Einstein condensates depends on not only the inter-atomic-molecular nonlinear interactions and the initial number of atoms in these condensates,but also the tunneling coupling between the atomic condensate and the multi-atomic molecular condensate.It is discovered that besides oscillating tunneling current between the atomic condensate and the multi-atomic molecular condensate,the nonlinear multi-atomic molecular tunneling dynamics sustains a self-locked population imbalance:a macroscopic quantum self-trapping effect.The influence of de-coherence caused by non-condensate atoms on the tunneling dynamics is studied.It is shown that de-coherence suppresses the multi-atomic molecular tunneling.Moreover,the conception of the molecular Bose-Einstein condensate,which is different from the conventional single-atomic Bose-Einstein condensate,is specially emphasized in this paper.
Environment-induced dynamics in a dilute Bose-Einstein condensate
Schelle, Alexej
2009-01-01
We directly model the quantum many particle dynamics during the transition of a gas of N indistinguishable bosons into a Bose-Einstein condensate. To this end, we develop a quantitative quantum master equation theory, which takes into account two body interaction processes, and in particular describes the particle number fluctuations characteristic for the Bose-Einstein phase transition. Within the Markovian dynamics assumption, we analytically prove and numerically verify the Boltzmann ergod...
Transition of a mesoscopic bosonic gas into a Bose-Einstein condensate
Schelle, Alexej
2011-01-01
The condensate number distribution during the transition of a dilute, weakly interacting gas of N=200 bosonic atoms into a Bose-Einstein condensate is modeled within number conserving master equation theory of Bose-Einstein condensation. Initial strong quantum fluctuations occuring during the exponential cycle of condensate growth reduce in a subsequent saturation stage, before the Bose gas finally relaxes towards the Gibbs-Boltzmann equilibrium.
Steady-state entanglement of a Bose-Einstein condensate and a nanomechanical resonator
Asjad, Muhammad; 10.1103/PhysRevA.84.033606
2011-01-01
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.
Vortices and Angular Momentum in Bose-Einstein-Condensed Cold Dark Matter Halos
Rindler-Daller, Tanja; Paul R. Shapiro
2009-01-01
If cold dark matter elementary particles form a Bose-Einstein condensate, their superfluidity may distinguish them from other forms of cold dark matter, including creation of quantum vortices. We demonstrate here that such vortices are favoured in strongly-coupled condensates, while this is not the case for axions, which are generally presumed to form a Bose-Einstein condensate but are effectively non-interacting.
Cold Atoms and Bose-Einstein Condensates in Optical Dipole Potentials
Nes, Johanna
2008-01-01
In 1925, Einstein predicted the condensation of bosons into the ground state of the system for low (but finite) temperatures. Several phenomena, including superfluidity and superconductivity have been associated with Bose-Einstein condensation, but these systems interact strongly with their environment and pure Bose-Einstein condensation could not be established. It took 70 years, in which time the laser was discovered, and laser cooling techniques to manipulate atoms in a dilute atomic gas, ...
Exact Hydrodynamics of a Trapped Dipolar Bose-Einstein Condensate
Eberlein, C.C.; O'Dell, D. H. J.; Giovanazzi, S.
2004-01-01
We present exact results in the Thomas-Fermi regime for the statics and dynamics of a harmonically trapped Bose-Einstein condensate that has dipole-dipole interactions in addition to the usual s-wave contact interactions. Remarkably, despite the nonlocal and anisotropic nature of the dipolar interactions, the density profile in a general time-dependent harmonic trap is an inverted parabola. The evolution of the condensate radii is governed by local, ordinary differential equations, and as an ...
Generalized Bose-Einstein Condensation
Mullin, William J
2010-01-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We analyze examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically occupied. We begin by discussing Type I or "normal" BEC into a single state for an isotropic harmonic oscillator potential. Other geometries and external potentials are then considered: the "channel" potential (harmonic in one dimension and hard-wall in the other), which displays Type II, the "cigar trap" (anisotropic harmonic potential), and the "Casimir prism" (an elongated box), the latter two having Type III condensations. General box geometries are considered in an appendix. We particularly focus on the cigar trap,...
Optimized production of a cesium Bose-Einstein condensate
Kraemer, Tobias; Herbig, Jens; Mark, Michael; Weber, Tino; Chin, Cheng; Naegerl, Hanns-Christoph; Grimm, Rudolf
2004-01-01
We report on the optimized production of a Bose-Einstein condensate of cesium atoms using an optical trapping approach. Based on an improved trap loading and evaporation scheme we obtain more than $10^5$ atoms in the condensed phase. To test the tunability of the interaction in the condensate we study the expansion of the condensate as a function of scattering length. We further excite strong oscillations of the trapped condensate by rapidly varying the interaction strength.
Kocharovsky, Vitaly V.; Kocharovsky, Vladimir V.; Holthaus, Martin; Ooi, C. H. Raymond; Svidzinsky, Anatoly A.; Ketterle, Wolfgang; Scully, Marlan O.
2006-01-01
We review the phenomenon of equilibrium fluctuations in the number of condensed atoms in a trap containing N atoms total. We start with a history of the Bose-Einstein distribution, the Einstein-Uhlenbeck debate concerning the rounding of the mean number of condensed atoms near a critical temperature, and a discussion of the relations between statistics of BEC fluctuations in the grand canonical, canonical, and microcanonical ensembles. Next we discuss different approaches capable of providing...
Recent developments in Bose-Einstein condensation
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.
Bose-Einstein Condensation in Satisfiability Problems
Angione, Claudio; Occhipinti, Annalisa; Stracquadanio, Giovanni; Nicosia, Giuseppe
2013-01-01
This paper is concerned with the complex behavior arising in satisfiability problems. We present a new statistical physics-based characterization of the satisfiability problem. Specifically, we design an algorithm that is able to produce graphs starting from a k-SAT instance, in order to analyze them and show whether a Bose-Einstein condensation occurs. We observe that, analogously to complex networks, the networks of k-SAT instances follow Bose statistics and can undergo Bose-Einstein conden...
Bose-Einstein condensation at constant temperature
Erhard, M.; Schmaljohann, H.; Kronjäger, J.; Bongs, K.; Sengstock, K.
2004-09-01
We present an experimental approach to Bose-Einstein condensation by increasing the particle number of the system at almost constant temperature. In particular, the emergence of a new condensate is observed in multicomponent F=1 spinor condensates of Rb87 . Furthermore, we develop a simple rate-equation model for multicomponent Bose-Einstein condensate thermodynamics at finite temperature which well reproduces the measured effects.
Scalar field as a Bose-Einstein condensate?
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
Scalar field as a Bose-Einstein condensate?
Castellanos, Elías; Escamilla-Rivera, Celia [Mesoamerican Centre for Theoretical Physics (ICTP regional headquarters in Central America, the Caribbean and Mexico), Universidad Autónoma de Chiapas, Carretera Zapata Km. 4, Real del Bosque (Terán), 29040, Tuxtla Gutiérrez, Chiapas (Mexico); Macías, Alfredo [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, A.P. 55-534, Mexico D.F. 09340 (Mexico); Núñez, Darío, E-mail: ecastellanos@mctp.mx, E-mail: cescamilla@mctp.mx, E-mail: amac@xanum.uam.mx, E-mail: nunez@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, Circuito Exterior C.U., A.P. 70-543, México D.F. 04510 (Mexico)
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.
Spin turbulence in spinor Bose-Einstein condensates
Tsubota, Makoto; Fujimoto, Kazuya
2013-01-01
We summarize the recent theoretical and numerical works on spin turbulence (ST) in spin-1 spinor Bose-Einstein condensates. When the system is excited from the ground state, it goes through hy- drodynamic instability to ST in which the spin density vector has various disordered direction. The properties of ST depend on whether the spin-dependent interaction is ferromagnetic or antiferro- magnetic. ST has some characteristics different from other kinds of turbulence in quantum fluids. Firstly,...
Observation of Faraday Waves in a Bose-Einstein Condensate
Engels, P.; Atherton, C.; Hoefer, M. A.
2007-01-01
Faraday waves in a cigar-shaped Bose-Einstein condensate are created. It is shown that periodically modulating the transverse confinement, and thus the nonlinear interactions in the BEC, excites small amplitude longitudinal oscillations through a parametric resonance. It is also demonstrated that even without the presence of a continuous drive, an initial transverse breathing mode excitation of the condensate leads to spontaneous pattern formation in the longitudinal direction. Finally, the e...
Photon-photon gates in Bose-Einstein condensates
Rispe, Arnaud; He, Bing; Simon, Christoph
2010-01-01
It has recently been shown that light can be stored in Bose-Einstein condensates for over a second. Here we propose a method for realizing a controlled phase gate between two stored photons. The photons are both stored in the ground state of the effective trapping potential inside the condensate. The collision-induced interaction is enhanced by adiabatically increasing the trapping frequency and by using a Feshbach resonance. A controlled phase shift of $\\pi$ can be achieved in one second.
A Bose-Einstein condensate in a microtrap
We describe an experiment to create a sizable 87Rb Bose-Einstein condensate (BEC) in a simple magnetic microtrap, created by a current through a Z-shaped wire and a homogeneous bias field. The BEC is created close to a reflecting surface. It is an ideal coherent source for experiments with cold atoms close to surfaces, be it small-volume microtraps or directly studying the interactions between cold atoms and a warm surface
Bose-Einstein Condensation in Exotic Trapping Potentials
Salasnich, Luca
2001-01-01
We discuss thermal and dynamical properties of Bose condensates confined by an external potential. First we analyze the Bose-Einstein transition temperature for an ideal Bose gas in a generic power-law potential and d-dimensional space. Then we investigate the effect of the shape of the trapping potential on the properties of a weakly-interacting Bose condensate. We show that using exotic trapping potentials the condensate can exhibit interesting coherent quantum phenomena, like superfluidity...
Modulated amplitude waves in Bose-Einstein condensates
We analyze spatiotemporal structures in the Gross-Pitaevskii equation to study the dynamics of quasi-one-dimensional Bose-Einstein condensates (BECs) with mean-field interactions. A coherent structure ansatz yields a parametrically forced nonlinear oscillator, to which we apply Lindstedt's method and multiple-scale perturbation theory to determine the dependence of the intensity of periodic orbits ('modulated amplitude waves') on their wave number. We explore BEC band structure in detail using Hamiltonian perturbation theory and supporting numerical simulations
Spectroscopic Test of Bose-Einstein Statistics for Photons
Using Bose-Einstein-statistics-forbidden two-photon excitation in atomic barium, we have limited the rate of statistics-violating transitions, as a fraction ν of an equivalent statistics-allowed transition rate, to ν-11 at the 90% confidence level. This is an improvement of more than 3 orders of magnitude over the best previous result. Additionally, hyperfine-interaction enabling of the forbidden transition has been observed, to our knowledge, for the first time.
Johnson, T H; Yuan, Y; Bao, W; Clark, S R; Foot, C; Jaksch, D
2016-06-17
We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes. PMID:27367366
Johnson, T. H.; Yuan, Y.; Bao, W.; Clark, S. R.; Foot, C.; Jaksch, D.
2016-06-01
We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes.
All optical cooling of $^{39}$K to Bose Einstein condensation
Salomon, Guillaume; Lepoutre, Steven; Aspect, Alain; Bourdel, Thomas
2014-01-01
We report the all-optical production of Bose Einstein condensates (BEC) of $^{39}$K atoms. We directly load $3 \\times 10^{7}$ atoms in a large volume optical dipole trap from gray molasses on the D1 transition. We then apply a small magnetic quadrupole field to polarize the sample before transferring the atoms in a tightly confining optical trap. Evaporative cooling is finally performed close to a Feshbach resonance to enhance the scattering length. Our setup allows to cross the BEC threshold with $3 \\times 10^5$ atoms every 7s. As an illustration of the interest of the tunability of the interactions we study the expansion of Bose-Einstein condensates in the 1D to 3D crossover.
YUAN Qing-Xin; DING Guo-Hui
2005-01-01
We investigate the phenomena of symmetry breaking and phase transition in the ground state of BoseEinstein condensates (BECs) trapped in a double square well and in an optical lattice well, respectively. By using standing-wave expansion method, we present symmetric and asymmetric ground state solutions of nonlinear Schrodinger equation (NLSE) with a symmetric double square well potential for attractive nonlinearity. In particular, we study the ground state wave function's properties by changing the depth of potential and atomic interactions (here we restrict ourselves to the attractive regime). By using the Fourier grid Hamiltonian method, we also reveal a phase transition of BECs trapped in one-dimensional optical lattice potential.
Growth of perturbations in an expanding universe with Bose-Einstein condensate dark matter
Chavanis, Pierre-Henri
2011-01-01
We study the growth of perturbations in an expanding Newtonian universe with Bose-Einstein condensate dark matter. We first ignore special relativistic effects and derive a differential equation governing the evolution of the density contrast in the linear regime taking into account quantum pressure and self-interaction. This equation can be solved analytically in several cases. We argue that an attractive self-interaction can enhance the Jeans instability and fasten the formation of structures. Then, we take into account pressure effects (coming from special relativity) in the evolution of the cosmic fluid and add the contribution of radiation, baryons and dark energy (cosmological constant). For a BEC dark matter with repulsive self-interaction (positive pressure) the scale factor increases more rapidly than in the standard \\Lambda CDM model where dark matter is pressureless while for a BEC dark matter with attractive self-interaction (negative pressure) it increases less rapidly. We study the linear develo...
For a system of N bosons in a two-dimensional harmonic trap with frequency ω, interacting via forces V<<(ℎ/2π)ω, we develop a method to find the ground states of rotating Bose condensate as a function of two quantum numbers, the total angular momentum and the angular momentum of internal excitations (generalized yrast states). The energies of these condensed vortex states are expressed through the single two-body matrix element of interaction, V. A broad universality class of predominantly repulsive interactions for which these results hold is described by a simple integral condition on V. It includes Gaussian, δ function, and log-Coulomb forces
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-T1/2=c, with k- the wave vector of the most unstable mode, T the sequence period, and c a sequence-dependent constant. Such a law between k- and T is also derived analytically for an attractive scalar Bose-Einstein condensate subjected to a periodic dynamical decoupling sequence.
Zhou, Zheng; Yu, Hui-You; Yan, Jia-Ren
2010-01-01
We present two kinds of exact vector-soliton solutions for coupled nonlinear Schrödinger equations with time-varying interactions and time-varying harmonic potential. Using the variational approach, we investigate the dynamics of the vector solitons. It is found that the two bright solitons oscillate about slightly and pass through each other around the equilibration state which means that they are stable under our model. At the same time, we obtain the opposite situation for dark-dark solitons.
Spontaneous formation of bright solitons in self-localized impurities in Bose-Einstein condensates
Boudjemâa, Abdelâali
2016-04-01
We study the formation of bright solitons in the impurity component of Bose-Einstein condensate-impurity mixture by using the time-dependent Hartree-Fock-Bogoliubov theory. While we assume the boson-boson and impurity-boson interactions to be effectively repulsive, their character can be changed spontaneously from repulsive to attractive in the presence of strong anomalous correlations. In such a regime the impurity component becomes a system of effectively attractive atoms leading automatically to the generation of bright solitons. We find that this soliton decays at higher temperatures due to the dissipation induced by the impurity-host and host-host interactions. We show that after a sudden increase of the impurity-boson strength a train of bright solitons is produced and this can be interpreted in terms of the modulational instability of the time-dependent impurity wave function.
Anticrossing effect between magnon and phonon in Bose-Einstein condensation phase of TlCuCl3
Raman spectra in TlCuCl3 under the magnetic field up to 12 T are reported. Above the critical magnetic field of the quantum phase transition to the magnon Bose-Einstein condensation phase, the one-magnon Raman peak is observed. Above 10 T, the one-magnon energy approaches the energy of the Ag phonon (3.1 meV) and the anticrossing effect is observed. By using the Green-function theory with three adjustable parameters, we estimate the amplitude of the attractive magnon-phonon interaction as 0.043 meV. The consistency between the present results and those of previous works is discussed.
Observation of Weak Collapse in a Bose-Einstein Condensate
Eigen, Christoph; Suleymanzade, Aziza; Navon, Nir; Hadzibabic, Zoran; Smith, Robert P
2016-01-01
We study the collapse of an attractive atomic Bose-Einstein condensate prepared in the uniform potential an optical-box trap. We characterise the critical point for collapse and the collapse dynamics, observing universal behaviour 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.
Ultracold Fermi gases: from Bose-Einstein condensation of molecules to Cooper pairs
Full text: We will describe recent experiments aiming at studying superfluidity in ultra-cold Fermi gases. Because of the Pauli exclusion principle, cooling methods and analysis techniques developed for bosons must be modified for fermions. Thanks to a resonance phenomenon in ultra-cold collisions, it is possible to adjust the sign and magnitude of the effective interaction between trapped fermions and to enter into the strongly correlated regime. Taking advantage of this tunability of interactions, it has been possible to produce Bose-Einstein condensates (BEC) of molecules and to study some of their properties. We will then present data recorded in the crossover region between BEC of molecules and the BCS regime of fermions with weak attractive interaction. Finally a few perspectives for this work at the interface between atomic physics and condensed matter physics will be given. (author)
Atomic Tunnelling Dynamics of Two Squeezed Bose-Einstein Condensates
LI Jin-Hui; KUANG Le-Man
2003-01-01
In this paper, tunnelling dynamics of squeezed Bose-Einstein condensates (BEC's) in the presence of the nonlinear self-interaction of each species, the interspecies nonlinear interaction, and the Josephson-like tunnelling interaction is investigated by using the second quantization approach. The influence of BEC squeezing on macroscopic quantum self-trapping (MQST) and quantum coherent atomic tunnelling is analyzed in detail. It is shown that the MQST and coherent atomic tunnelling between two squeezed BEC's can be manipulated through changing squeezing amplitude and squeezing phase of BEC squeezed states.
Nonlinear Wave in a Disc-Shaped Bose-Einstein Condensate
DUAN Wen-Shan; CHEN Jian-Hong; YANG Hong-Juan; SHI Yu-Ren; WANG Hong-Yan
2006-01-01
@@ We discuss the possible nonlinear wavesof atomic matter wave in a Bose-Einstein condensate. One and two of two-dimensional (2D) dark solitons in the Bose-Einstein condensed system are investigated. A rich dynamics is studied for the interactions between two solitons. The interaction profiles of two solitons are greatly different if the angle between them are different. If the angle is small enough, the maximum amplitude during the interaction between two solitons is even less than that of a single soliton. However, if the angle is large enough, the maximum amplitude of two solitons can gradually attend to the sum of two soliton amplitudes.
Bose-Einstein Condensate and Gravitational Shielding
De Aquino, Fran
2014-01-01
In this work we show that when possible transform some types of substance into a Bose-Einstein condensate at room temperature, which exists long enough to be used in practice then will be possible to use these substances in order to create efficient Gravitational Shieldings.
Skyrmion physics in Bose-Einstein ferromagnets
Al Khawaja, U.; Stoof, H.T.C.
2001-01-01
We show that a ferromagnetic Bose-Einstein condensate has not only line-like vortex excitations, but in general also allows for point-like topological excitations, i.e., skyrmions. We discuss the thermodynamic stability and the dynamic properties of these skyrmions for both spin-1/2 and ferromagnetic spin-1 Bose gases.
Chaos in a Bose-Einstein condensate
Wang Zhi-Xia; Ni Zheng-Guo; Cong Fu-Zhong; Liu Xue-Shen; Chen Lei
2010-01-01
It is demonstrated that Smale-horseshoe chaos exists in the time evolution of the one-dimensional Bose-Einstein condensate driven by time-periodic harmonic or inverted-harmonic potential.A formally exact solution of the timedependent Gross-Pitaevskii equation is constructed,which describes the matter shock waves with chaotic or periodic amplitudes and phases.
Bose-Einstein correlations between kaons
Bose-Einstein correlations between identical charged kaons are observed in αα, pp, and panti p collisions at the CERN Intersecting Storage Rings. The average radial extension of the K-emitting region is found to be (2.4+-0.9) fm. (orig.)
Initial stages of Bose-Einstein condensation
Stoof, H.T.C.
1997-01-01
We present the quantum theory for the nucleation of Bose-Einstein condensation in a dilute atomic Bose gas. This quantum theory has the important advantage that both the kinetic and coherent stages of the nucleation process can be described in a unified way by a single Fokker-Planck equation.
Initial stages of Bose-Einstein condensation
Stoof, H.T.C.
2001-01-01
We present the quantum theory for the nucleation of Bose-Einstein condensation in a dilute atomic Bose gas. This quantum theory confirms the results of the semiclassical treatment, but has the important advantage that both the kinetic and coherent stages of the nucleation process can now be describe
Gigantic excitation of Bose-Einstein condensate
Karkuszewski, Z P; Zakrzewski, J; Karkuszewski, Zbyszek P.; Sacha, Krzysztof; Zakrzewski, Jakub
2001-01-01
It is shown that by a modification of the trapping potential one may excite Bose-Einstein condensate to a state in which atomic external degrees of freedom are predominantly in the {\\it excited} trap state. Such an excited condensate can be prepared experimentally --- it requires only a proper change in time of the potential in atomic traps, as realized in laboratories already.
Stirring a Bose-Einstein condensate
Damski, Bogdan [Instytut Fizyki Imienia Mariana Smoluchowskiego, Uniwersytet Jagiellonski, Cracow (Poland); Institut fuer Theoretische Physik, Universitaet Hannover, Hannover (Germany); Sacha, Krzysztof; Zakrzewski, Jakub [Instytut Fizyki Imienia Mariana Smoluchowskiego, Uniwersytet Jagiellonski, Cracow (Poland)
2002-10-14
By shining a tightly focused laser light on a Bose-Einstein condensate (BEC) and moving the centre of the beam along a spiral path one may stir the BEC and create vortices. It is shown that one can induce rotation of the BEC in the direction opposite to the direction of stirring. (author)
Band structures of a dipolar Bose-Einstein condensate in one-dimensional lattices
Lin, Yuanyao; Lee, Ray-Kuang; Kao, Yee-Mou; Jiang, Tsin-Fu
2008-08-01
We derive the effective Gross-Pitaevskii equation for a cigar-shaped dipolar Bose-Einstein condensate in one-dimensional lattices and investigate the band structures numerically. Due to the anisotropic and the long-ranged dipole-dipole interaction in addition to the known contact interaction, we elucidate the possibility of modifying the band structures by changing the alignment of the dipoles with the axial direction. With the considerations of the transverse parts and the practical physical parameters of a cigar-shaped trap, we show the possibility to stabilize an attractive condensate simply by adjusting the orientation angle of dipoles. Some interesting Bloch waves at several particle current densities are identified for possible experimental observations.
Impurity in a Bose-Einstein Condensate and the Efimov Effect.
Levinsen, Jesper; Parish, Meera M; Bruun, Georg M
2015-09-18
We investigate the zero-temperature properties of an impurity particle interacting with a Bose-Einstein condensate (BEC), using a variational wave function that includes up to two Bogoliubov excitations of the BEC. This allows one to capture three-body Efimov physics, as well as to recover the first nontrivial terms in the weak-coupling expansion. We show that the energy and quasiparticle residue of the dressed impurity (polaron) are significantly lowered by three-body correlations, even for weak interactions where there is no Efimov trimer state in a vacuum. For increasing attraction between the impurity and the BEC, we observe a smooth crossover from atom to Efimov trimer, with a superposition of states near the Efimov resonance. We furthermore demonstrate that three-body loss does not prohibit the experimental observation of these effects. Our results thus suggest a route to realizing Efimov physics in a stable quantum many-body system for the first time. PMID:26430999
Probing a Bose-Einstein Condensate with an Atom Laser
Döring, D.; Robins, N. P.; Figl, C.; Close, J. D.
2008-01-01
A pulsed atom laser derived from a Bose-Einstein condensate is used to probe a second target condensate. The target condensate scatters the incident atom laser pulse. From the spatial distribution of scattered atoms, one can infer important properties of the target condensate and its interaction with the probe pulse. As an example, we measure the s-wave scattering length that, in low energy collisions, describes the interaction between the |F=1,m_F=-1> and |F=2,m_F=0> hyperfine ground states ...
Behaviour of Rotating Bose-Einstein Condensates Under Shrinking
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 satiated 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].
We investigate exact nonlinear matter wave functions with odd and even parities in the framework of quasi-two-dimensional Bose-Einstein condensates (BECs) with spatially modulated cubic-quintic nonlinearities and harmonic potential. The existence condition for these exact solutions requires that the minimum energy eigenvalue of the corresponding linear Schroedinger equation with harmonic potential is the cutoff value of the chemical potential λ. The competition between two-body and three-body interactions influences the energy of the localized state. For attractive two-body and three-body interactions, the larger the matter wave order number n, the larger the energy of the corresponding localized state. A linear stability analysis and direct simulations with initial white noise demonstrate that, for the same state (fixed n), increasing the number of atoms can add stability. A quasi-stable ground-state matter wave is also found for repulsive two-body and three-body interactions. We also discuss the experimental realization of these results in future experiments. These results are of particular significance to matter wave management in higher-dimensional BECs. - Highlights: → 2D Bose-Einstein condensates (BECs) with spatially modulated cubic-quintic nonlinearities and the harmonic potential are discussed. → 2D exact quantized nonlinear matter wave functions with the odd and even parities are obtained. → The 2D ground-state matter wave with attractive two-body and repulsive three-body interactions is stable. → Experimental realization of our results in future experiments is proposed.
Observation of Faraday Waves in a Bose-Einstein Condensate
Engels, Peter; Atherton, Collin; Hoefer, Mark
2007-06-01
Faraday waves in a cigar-shaped Bose-Einstein condensate are created. It is shown that periodically modulating the transverse confinement, and thus the nonlinear interactions in the BEC, excites small amplitude longitudinal oscillations through a parametric resonance. It is also demonstrated that even without the presence of a continuous drive, an initial transverse breathing mode excitation of the condensate leads to spontaneous pattern formation in the longitudinal direction. Finally, the effects of strongly driving the transverse breathing mode with large amplitude are investigated. In this case, impact-oscillator behavior and intriguing nonlinear dynamics, including the gradual emergence of multiple longitudinal modes, are observed.
A Raman waveplate for spinor Bose-Einstein condensates.
Schultz, Justin T; Hansen, Azure; Bigelow, Nicholas P
2014-07-15
We demonstrate a waveplate for a pseudo-spin-1/2 Bose-Einstein condensate (BEC) using a two-photon Raman interaction. The angle of the waveplate is set by the relative phase of the optical fields, and the retardance is controlled by the pulse area. The waveplate allows us to image maps of the Stokes parameters of a BEC and thereby measure its relative ground-state phase. We demonstrate the waveplate by measuring the Stokes parameters of a coreless vortex. PMID:25121704
Analytic vortex dynamics in an annular Bose-Einstein condensate
Toikka, L. A.; Suominen, K.-A.
2016-05-01
We consider analytically the dynamics of an arbitrary number and configuration of vortices in an annular Bose-Einstein condensate obtaining expressions for the free energy and vortex precession rates to logarithmic accuracy. We also obtain lower bounds for the lifetime of a single vortex in the annulus. Our results enable a closed-form analytic treatment of vortex-vortex interactions in the annulus that is exact in the incompressible limit. The incompressible hydrodynamics that is developed here paves the way for more general analytical treatments of vortex dynamics in non-simply-connected geometries.
Collisions of Dark Solitons in Elongated Bose-Einstein Condensates
We present experimental data showing the head-on collision of dark solitons generated in an elongated Bose-Einstein condensate. No discernable interaction can be recorded, in full agreement with the fundamental theoretical concepts of solitons as mutually transparent quasiparticles. Our soliton generation technique allows for the creation of solitons with different depths; hence, they can be distinguished and their trajectories be followed. Simulations of the 1D-Gross-Pitaevskii equation have been performed to compare the experiment with a mean-field description
Stability of self-gravitating Bose-Einstein-Condensates
Schroven, Kris; Lämmerzahl, Claus
2015-01-01
We study the ground state and the first three radially excited states of a self-gravitating Bose-Einstein- Condensate with respect to the influence of two external parameters, the total mass and the strength of interactions between particles. For this we use the so-called Gross-Pitaevskii-Newton system. In this context we especially determine the case of very high total masses where the ground state solutions of the Gross-Pitaevskii- Newton system can be approximated with the Thomas-Fermi limit. Furthermore, stability properties of the computed radially excited states are examined by applying arguments of the catastrophe theory.
High visibility gravimetry with a Bose-Einstein condensate
Debs, J E; Barter, T H; Döring, D; Dennis, G R; McDonald, G; Robins, N P; Close, J D
2010-01-01
We present results from an atomic gravimeter using a Bose-Einstein condensate with fringe visibility up to 85%. A direct comparison with a thermal state displays a significant increase in visibility for a condensed source. We do not observe any detrimental effects of atom-atom interactions, provided the cloud is allowed to reach the ballistic free-expansion regime. By increasing the space-time area enclosed by our interferometer using large-momentum-transfer beamsplitters, we achieve a precision of 17 ppm in a measurement of the local acceleration due to gravity.
Solitons, Bose-Einstein condensation and superfluidity in He II
The analytic form of a wave propagating with a constant velocity and a permanent profile is inferred for a weakly interacting Bose gas, using an exact (rather than asymptotic) solution of the field equation of the self-consistent Hartree model. The significance of this approach is indicated, especially when realistic interatomic potentials are used. In addition, the general relation between solitons and Bose-Einstein condensation is underlined by invoking the profound insight recently acquired in studies of the quantum liquids involved in the living state. It is concluded that solitons may occur in He II, and may play a significant role in the phenomena of superfluidity. (author)
Hidden vorticity in binary Bose-Einstein condensates
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 S1,2=±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.
Effect of Dimple Potential on Ultraslow Light in a Bose-Einstein Condensate
Tarhan, Devrim; Uncu, Haydar
2012-01-01
We investigate the propagation of ultraslow optical pulse in atomic Bose-Einstein condensate in a harmonic trap decorated with a dimple potential. The role of dimple potential on the group velocity and time delay is studied. Since we consider the interatomic scattering interactions nonlinear Schrodinger equation or Gross-Pitaevskii equation is used in order to get the density profile of the atomic system. We find large group delays of order 1 msec in an atomic Bose-Einstein condensate in a ha...
Einstein--de Haas Effect in Dipolar Bose-Einstein Condensates
Kawaguchi, Yuki; Saito, Hiroki; Ueda, Masahito
2005-01-01
The general properties of the order parameter for a dipolar spinor Bose-Einstein condensate are discussed based on symmetries of interactions. An initially spin-polarized dipolar condensate is shown to dynamically generate a non-singular vortex via spin-orbit interactions -- a phenomenon reminiscent of the Einstein--de Haas effect in ferromagnets.
Astrophysical Bose-Einstein Condensates and Superradiance
Kuhnel, Florian
2014-01-01
We investigate gravitational analogue models to describe slowly rotating objects (e.g., dark-matter halos, or boson stars) in terms of Bose-Einstein condensates, trapped in their own gravitational potentials. We begin with a modified Gross-Pitaevskii equation, and show that the resulting background equations of motion are stable, as long as the rotational component is treated as a small perturbation. The dynamics of the fluctuations of the velocity potential are effectively governed by the Klein-Gordon equation of a "Eulerian metric", where we derive the latter by the use of a relativistic Lagrangian extrapolation. Superradiant scattering on such objects is studied. We derive conditions for its occurence and estimate its strength. Our investigations might give an observational handle to phenomenologically constrain Bose-Einstein condensates.
Numerical modelling of Bose-Einstein correlations
Utyuzh, O. V.; Wilk, G.; Wlodarczyk, Z.
2001-01-01
We propose extension of the algorithm for numerical modelling of Bose-Einstein correlations (BEC), which was presented some time ago in the literature. It is formulated on quantum statistical level for a single event and uses the fact that identical particles subjected to Bose statistics do bunch themselves, in a maximal possible way, in the same cells in phase-space. The bunching effect is in our case obtained in novel way allowing for broad applications and fast numerical calculations. Firs...
Entangled light from Bose-Einstein condensates
Ng, H. T.; Bose, S.
2008-01-01
We propose a method to generate entangled light with a Bose-Einstein condensate trapped in a cavity, a system realized in recent experiments. The atoms of the condensate are trapped in a periodic potential generated by a cavity mode. The condensate is continuously pumped by a laser and spontaneously emits a pair of photons of different frequencies in two distinct cavity modes. In this way, the condensate mediates entanglement between two cavity modes, which leak out and can be separated and e...
Bose-Einstein condensation of 84Sr.
Martinez de Escobar, Y N; Mickelson, P G; Yan, M; DeSalvo, B J; Nagel, S B; Killian, T C
2009-11-13
We report Bose-Einstein condensation of (84)Sr 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 (N(0) approximately 3 x 10(5)) 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. PMID:20365965
Bose-Einstein Condensation of 84-Sr
de Escobar, Y. N. Martinez; Mickelson, P. G.; Yan, M; DeSalvo, B. J.; Nagel, S. B.; Killian, T. C.
2009-01-01
We report Bose-Einstein condensation of 84-Sr in an optical dipole trap. Efficient laser cooling on the narrow intercombination line and an ideal s-wave scattering length allow creation of large condensates (N0 ~ 3x10^5) 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.
Smyrnakis, J.; Magiropoulos, M.; Kavoulakis, G. M.; Jackson, A. D.
2013-01-01
We derive solitary-wave solutions within the mean-field approximation in quasi-one-dimensional binary mixtures of Bose-Einstein condensates under periodic boundary conditions, for the case of an effective repulsive interatomic interaction. The particular gray-bright solutions that give the global energy minima are determined. Their characteristics and the associated dispersion relation are derived.
Infinitely-long-range nonlocal potentials and the Bose-Einstein supersolid phase
Alexanian, Moorad
2011-01-01
It is shown, with the aid of the Bogoliubov inequality, that a Bose-Einstein condensate has the Bloch form and represents a self-organized supersolid provided the interaction between the condensate atoms is nonlocal and of infinitely long-range.
Phase separation and dynamics of two-component Bose-Einstein condensates
Lee, Kean Loon; Jørgensen, Nils Byg; Liu, I-Kang;
2016-01-01
The miscibility of two interacting quantum systems is an important testing ground for the understanding of complex quantum systems. Two-component Bose-Einstein condensates enable the investigation of this scenario in a particularly well controlled setting. In a homogeneous system, the transition ...
Stability of Two-Component Bose-Einstein Condensates in Bessel Optical Lattices
FU Hong-Zhi; CHEN Hai-Jun; LI De-Hua; LI Hao-Cai; PENG Feng; XUE Ju-Kui; GAO Tao; CHENG Xin-Lu
2008-01-01
The stability of the ground state of two-component Bose-Einstein condensates (BECs) loaded into the central well of an axially symmetric Bessel lattices (BLs) potential with attractive or repulsive atoms interactions is studied using the time-dependent Gross-Pitaevskii equation (GPE). By using the variational method, we find that stable ground state of two-component BECs can exist in BLs. The BLs's depth and the intra-species atom interaction play an important role in the stability of ground state. The collapse of two-component BECs in BLs is also studied and a collapse condition for trapped two-component BECs is obtained. It is shown that the two-component BECs exhibit rich collapse dynamics. That is, the two-component BECs can collapse in the system with both intra- and inter-attractive, or with intra-attractive and inter-repulsive, or with intra-repulsive and inter-attractive atom interactions. Furthermore, the control of the collapse of the two-component BECs in BLs is discussed in detail The stability diagram of the ground state in parameter space is obtained. The results show that the collapse of two-component BECs can be controlled by temporal modulation of the atom interaction.
Dynamics of macroscopic tunneling in elongated Bose-Einstein condensates
We investigate macroscopic tunneling from an elongated quasi-one-dimensional trap, forming a 'cigar-shaped' Bose-Einstein condensate (BEC). Using a recently developed formalism we get the leading analytical approximation for the right-hand side of the potential wall, i.e., outside the trap, and a formalism based on Wigner functions, for the left side of the potential wall, i.e., inside the BEC. We then present accomplished results of numerical calculations, which show a 'blip' in the particle density traveling with an asymptotic shock velocity, as resulted from previous works on a dotlike trap but with significant differences from the latter. Inside the BEC a pattern of a traveling dispersive shock wave is revealed. In the attractive case, we find trains of bright solitons frozen near the boundary.
Knot Solitons in Spinor Bose-Einstein Condensates
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.
Critical rotation of an anharmonically trapped Bose-Einstein condensate
Ma Juan; Li Zhi; Xue Ju-Kui
2009-01-01
We consider rotational motion of an interacting atomic Bose-Einstein condensate (BEC) with both two- and threebody interactions in a quadratic-plus-quartic and harmonic-plus-Gaussian trap. By using the variational method, the influence of the three-body interaction and the anharmonicity of the trap on the lowest energy surface mode excitation and the spontaneous shape deformation (responsible for the vortex formation) in a rotating BEC is discussed in detail. It is found that the repulsive three-body interaction helps the formation of the vortex and reduces the lowest energy surface mode frequency and the critical rotational frequency of the system. Moreover, the critical rotational frequency for the vortex formation in the harmonic-plus-Gaussian potential is lower than that in the quadratic-plus-quartic potential.
Numerical modelling of Bose-Einstein correlations
Utyuzh, O V; Wlodarczyk, Z
2001-01-01
We propose extension of the algorithm for numerical modelling of Bose-Einstein correlations (BEC), which was presented some time ago in the literature. It is formulated on quantum statistical level for a single event and uses the fact that identical particles subjected to Bose statistics do bunch themselves, in a maximal possible way, in the same cells in phase-space. The bunching effect is in our case obtained in novel way allowing for broad applications and fast numerical calculations. First comparison with $e^+e^-$ annihilations data performed by using simple cascade hadronization model is very encouraging.
Bose-Einstein condensation in layered systems
Haerdig, A
1993-01-01
The thermodynamic properties of an ideal gas of bosons moving freely within layered planes and having a finite amplitude for jumping between neighbouring planes, are derived. As long as this coupling is non-zero, the system becomes effectively two-dimensional at sufficiently high temperatures. At a correspondingly low temperature it undergoes a Bose-Einstein transition into a condensed phase as in three dimensions. Below the critical temperature the specific heat is a universal function of only one dimensionless system variable. The phase transition becomes weaker as the coupling between the planes decreases and eventually disappears when the planes decouple. (author)
Bose-Einstein Condensation of Atomic Hydrogen
Fried, Dale G.
1999-01-01
This thesis describes the observation and study of Bose-Einstein condensation of a trapped, dilute gas of atomic hydrogen. The condensate and normal gas are studied by two-photon spectroscopy of the 1S-2S transition. We condense over 10^9 atoms per second for several seconds, and the peak condensate density is around 5x10^15 cm^-3. Topics covered in the thesis include a theoretical analysis of Bose-condensed hydrogen, a description of the cryogenic trapping cell and the evaporative cooling te...
Analog gravity from Bose-Einstein condensates
Barcelo, Carlos; Liberati, Stefano; Visser, Matt
2000-01-01
We analyze prospects for the use of Bose-Einstein condensates as condensed-matter systems suitable for generating a generic ``effective metric'', and for mimicking kinematic aspects of general relativity. We extend the analysis due to Garay et al, [gr-qc/0002015, gr-qc/0005131]. Taking a long term view, we ask what the ultimate limits of such a system might be. To this end, we consider a very general version of the nonlinear Schrodinger equation (with a 3-tensor position-dependent mass and ar...
Transport of Bose-Einstein condensates through two dimensional cavities
The recent experimental advances in manipulating ultra-cold atoms make it feasible to study coherent transport of Bose-Einstein condensates (BEC) through various mesoscopic structures. In this work the quasi-stationary propagation of BEC matter waves through two dimensional cavities is investigated using numerical simulations within the mean-field approach of the Gross-Pitaevskii equation. The focus is on the interplay between interference effects and the interaction term in the non-linear wave equation. One sees that the transport properties show a complicated behaviour with multi-stability, hysteresis and dynamical instabilities for non-vanishing interaction. Furthermore, the prominent weak localization effect, which is a robust interference effect emerging after taking a configuration average, is reduced and partially inverted for non-vanishing interaction.
Spin turbulence in spinor Bose-Einstein condensates
We summarize the recent theoretical and numerical works on spin turbulence (ST) in spin-1 spinor Bose-Einstein condensates. When the system is excited from the ground state, it goes through hydrodynamic instability to ST in which the spin density vector has various disordered direction. The properties of ST depend on whether the spin-dependent interaction is ferromagnetic or antiferromagnetic. ST has some characteristics different from other kinds of turbulence in quantum fluids. Firstly, the spectrum of the spin-dependent interaction energy exhibits the characteristic power law different from the usual Kolmogorov -5/3 law. Secondly, ST can show the spin-glass-like behavior; the spin density vectors are spatially random but temporally frozen.
Gravity, Bose-Einstein Condensates and Gross-Pitaevskii Equation
Gupta, Patrick Das
2015-01-01
We explore the effect of mutual gravitational interaction between ultra-cold gas atoms on the dynamics of Bose-Einstein condensates (BEC). Small amplitude oscillation of BEC is studied by applying variational technique to reduce the Gross-Pitaevskii equation, with gravity included, to the equation of motion of a particle moving in a potential. According to our analysis, if the s-wave scattering length can be tuned to zero using Feshbach resonance for future BEC with occupation numbers as high as $\\approx 10^{20}$, there exists a critical ground state occupation number above which the BEC is unstable, provided that its constituents interact with a $1/r^3 $ gravity at short scales.
Analog gravity from Bose-Einstein condensates
Barcelo, C; Visser, M; Barcelo, Carlos; Liberati, Stefano; Visser, Matt
2001-01-01
We analyze prospects for the use of Bose-Einstein condensates as condensed-matter systems suitable for generating a generic ``effective metric'', and for mimicking kinematic aspects of general relativity. We extend the analysis due to Garay et al, [gr-qc/0002015, gr-qc/0005131]. Taking a long term view, we ask what the ultimate limits of such a system might be. To this end, we consider a very general version of the nonlinear Schrodinger equation (with a 3-tensor position-dependent mass and arbitrary nonlinearity). Such equations can be used for example in discussing Bose-Einstein condensates in heterogeneous and highly nonlinear systems. We demonstrate that at low momenta linearized excitations of the phase of the condensate wavefunction obey a (3+1)-dimensional d'Alembertian equation coupling to a (3+1)-dimensional Lorentzian-signature ``effective metric'' that is generic, and depends algebraically on the background field. Thus at low momenta this system serves as an analog for the curved spacetime of genera...
Thermalization and Bose-Einstein Condensation in Overpopulated Glasma
Blaizot, Jean-Paul; Gelis, François [Institut de Physique Théorique (URA 2306 du CNRS), CEA/DSM/Saclay, 91191, Gif-sur-Yvette Cedex (France); Liao, Jinfeng [Physics Department and CEEM, Indiana University, 2401 N Milo B. Sampson Lane, Bloomington, IN 47408 (United States); RIKEN BNL Research Center, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States); McLerran, Larry [Physics Department, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States); RIKEN BNL Research Center, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States); Venugopalan, Raju [Physics Department, Bldg. 510A, Brookhaven National Laboratory, Upton, NY 11973 (United States)
2013-05-02
We report recent progress on understanding the thermalization of the quark-gluon plasma during the early stage in a heavy ion collision. The initially high overpopulation in the far-from-equilibrium gluonic matter (“Glasma”) is shown to play a crucial role. The strongly interacting nature (and thus fast evolution) naturally arises as an emergent property of this pre-equilibrium matter where the intrinsic coupling is weak but the highly occupied gluon states coherently amplify the scattering. A possible transient Bose-Einstein Condensate is argued to form dynamically on a rather general ground. We develop a kinetic approach for describing its evolution toward thermalization as well as the onset of condensation.
Thermalization and Bose-Einstein Condensation in Overpopulated Glasma
Blaizot, Jean-Paul; Liao, Jinfeng; McLerran, Larry; Venugopalan, Raju
2012-01-01
We report recent progress on understanding the thermalization of the quark-gluon plasma during the early stage in a heavy ion collision. The initially high overpopulation in the far-from-equilibrium gluonic matter ("Glasma") is shown to play a crucial role. The strongly interacting nature (and thus fast evolution) naturally arises as an {\\em emergent property} of this pre-equilibrium matter where the intrinsic coupling is weak but the highly occupied gluon states coherently amplify the scattering. A possible transient Bose-Einstein Condensate is argued to form dynamically on a rather general ground. We develop a kinetic approach for describing its evolution toward thermalization, and based on that we find approximate scaling solutions as well as numerically study the onset of condensation.
Tunable Bistability in Hybrid Bose-Einstein Condensate Optomechanics
Yasir, Kashif Ammar
2015-01-01
Cavity-optomechanics, a rapidly developing area of research, has made a remarkable progress. A stunning manifestation of optomechanical phenomena is in exploiting the mechanical effects of light to couple the optical degree of freedom with mechanical degree of freedom. In this report, we investigate the controlled bistable dynamics of such hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC) trapped inside high-finesse optical cavity with one moving-end mirror and is driven by a single mode optical field. The numerical results provide evidence for controlled optical bistability in optomechanics using transverse optical field which directly interacts with atoms causing the coupling of transverse field with momentum side modes, exited by intra-cavity field. This technique of transverse field coupling is also used to control bistable dynamics of both moving-end mirror and BEC. The report provides an understanding of temporal dynamics of moving-end mirror and BEC with respect to tr...
Thermalization and Bose-Einstein Condensation in Overpopulated Glasma
We report recent progress on understanding the thermalization of the quark-gluon plasma during the early stage in a heavy ion collision. The initially high overpopulation in the far-from-equilibrium gluonic matter (“Glasma”) is shown to play a crucial role. The strongly interacting nature (and thus fast evolution) naturally arises as an emergent property of this pre-equilibrium matter where the intrinsic coupling is weak but the highly occupied gluon states coherently amplify the scattering. A possible transient Bose-Einstein Condensate is argued to form dynamically on a rather general ground. We develop a kinetic approach for describing its evolution toward thermalization as well as the onset of condensation
Ultracold Bose Gases in 1D Disorder: From Lifshits Glass to Bose-Einstein Condensate
Lugan, Pierre; Clément, David; Bouyer, Philippe; Aspect, Alain; Lewenstein, Maciej; Sanchez-Palencia, Laurent
2007-01-01
We study an ultracold Bose gas in the presence of 1D disorder for repulsive inter-atomic interactions varying from zero to the Thomas-Fermi regime. We show that for weak interactions the Bose gas populates a finite number of localized single-particle Lifshits states, while for strong interactions a delocalized disordered Bose-Einstein condensate is formed. We discuss the schematic quantum-state diagram and derive the equations of state for various regimes.
Numerical study of localized impurity in a Bose-Einstein condensate
Akram, Javed; Pelster, Axel
2016-03-01
Motivated by recent experiments, we investigate a single 133 Cs impurity in the center of a trapped 87 Rb Bose-Einstein condensate (BEC). Within a zero-temperature mean-field description we provide a one-dimensional physical intuitive model which involves two coupled differential equations for the condensate and the impurity wave function, which we solve numerically. With this we determine within the equilibrium phase diagram spanned by the intra- and interspecies coupling strength whether the impurity is localized at the trap center or expelled to the condensate border. In the former case we find that the impurity induces a bump or dip on the condensate for an attractive or a repulsive Rb-Cs interaction strength, respectively. Conversely, the condensate environment leads to an effective mass of the impurity which increases quadratically for small interspecies interaction strength. Afterwards, we investigate how the impurity imprint upon the condensate wave function evolves for two quench scenarios. At first we consider the case that the harmonic confinement is released. During the resulting time-of-flight expansion it turns out that the impurity-induced bump in the condensate wave function starts decaying marginally, whereas the dip decays with a characteristic time scale which decreases with increasing repulsive impurity-BEC interaction strength. Second, once the attractive or repulsive interspecies coupling constant is switched off, we find that white-shock waves or bisolitons emerge which both oscillate within the harmonic confinement with a characteristic frequency.
Law, K J H; Kevrekidis, P G [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Anderson, B P [College of Optical Sciences and Department of Physics, University of Arizona, Tucson, AZ 85721 (United States); Carretero-Gonzalez, R [Nonlinear Dynamical Systems Group, Department of Mathematics and Statistics, San Diego State University, San Diego, California 92182-7720 (United States); Frantzeskakis, D J [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 15784 (Greece)], E-mail: law@math.umass.edu
2008-10-14
In this work, we study two-dimensional Bose-Einstein condensates confined by both a cylindrically symmetric harmonic potential and an optical lattice with equal periodicity in two orthogonal directions. We first identify the spectrum of the underlying two-dimensional linear problem through multiple-scale techniques. Then, we use the results obtained in the linear limit as a starting point for the existence and stability analysis of the lowest energy states, emanating from the linear ones, in the nonlinear problem. Two-parameter continuations of these states are performed for increasing nonlinearity and optical lattice strengths, and their instabilities and temporal evolution are investigated. It is found that the ground state as well as some of the excited states may be stable or weakly unstable for both attractive and repulsive interatomic interactions. Higher excited states are typically found to be increasingly more unstable.
Bose-Einstein Condensation of Metastable Helium
Dos Santos, F. Pereira; Léonard, J.; Wang, Junmin; Barrelet, C. J.; Perales, F.; Rasel, E.; Unnikrishnan, C. S.; Leduc, M.; Cohen-Tannoudji, C.
2001-04-01
We have observed a Bose-Einstein condensate in a dilute gas of 4He in the 32S1 metastable state. We find a critical temperature of \\(4.7+/-0.5\\) μK and a typical number of atoms at the threshold of 8×106. The maximum number of atoms in our condensate is about 5×105. An approximate value for the scattering length a = \\(16+/-8\\) nm is measured. The mean elastic collision rate at threshold is then estimated to be about 2×104 s-1, indicating that we are deeply in the hydrodynamic regime. The typical decay time of the condensate is 2 s, which places an upper bound on the rate constants for two-body and three-body inelastic collisions.
Optimized production of large Bose Einstein Condensates
Comparat, D; Fioretti, A; Pillet, P; Stern, G; Tolra, B L
2006-01-01
We suggest different simple schemes to efficiently load and evaporate a ''dimple'' crossed dipolar trap. The collisional processes between atoms which are trapped in a reservoir load in a non adiabatic way the dimple. The reservoir trap can be provided either by a dark SPOT Magneto Optical Trap, the (aberrated) laser beam itself or by a quadrupolar or quadratic magnetic trap. Optimal parameters for the dimple are derived from thermodynamical equations and from loading time, including possible inelastic and Majorana losses. We suggest to load at relatively high temperature a tight optical trap. Simple evaporative cooling equations, taking into account gravity, the possible occurrence of hydrodynamical regime, Feshbach resonance processes and three body recombination events are given. To have an efficient evaporation the elastic collisional rate (in s$^{-1}$) is found to be on the order of the trapping frequency and lower than one hundred times the temperature in micro-Kelvin. Bose Einstein condensates with mor...
Number-conserving master equation theory for a dilute Bose-Einstein condensate
Schelle, Alexej; Wellens, Thomas; Delande, Dominique; Buchleitner, Andreas
2010-01-01
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 non-condensate thermalization, we derive a master equation for the condensate subsystem in the presence of the non-condensate environment under the inclusion of all two body interaction processes. We numerically monitor the condensate particle number distribution during condensa...
Parametric amplification of matter waves in dipolar spinor Bose-Einstein condensates
Deuretzbacher, F.; Gebreyesus, G.; Topic, O.;
2010-01-01
Spin-changing collisions may lead under proper conditions to the parametric amplification of matter waves in spinor Bose-Einstein condensates. Magnetic dipole-dipole interactions, although typically very weak in alkali-metal atoms, are shown to play a very relevant role in the amplification process......-field gradients, hence, must be carefully controlled in future experiments, in order to observe clearly the effects of the dipolar interactions in the amplification dynamics....
Exactly solvable models for multiatomic molecular Bose-Einstein condensates
Santos, G, E-mail: gfilho@if.ufrgs.br, E-mail: gfilho@cbpf.br [Instituto de Fisica da UFRGS, Av. Bento Goncalves, 9500, Agronomia, Porto Alegre, RS (Brazil)
2011-08-26
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. (paper)
Stability of the Bose-Einstein condensate under polynomial perturbations
Gielerak, R.; Damek, J.
2002-01-01
The problem of the Bose-Einstein condensate preservation under thermofield and standard gauge-invariant perturbations is discussed. A new result on stability of the condensate under thermofield perturbations of a polynomial type is presented.
Inelastic chaotic scattering on a Bose-Einstein condensate
Hunn, Stefan; Hiller, Moritz; Buchleitner, Andreas; Cohen, Doron; Kottos, Tsampikos
2010-01-01
We devise a microscopic scattering approach to probe the excitation spectrum of a Bose-Einstein condensate. We show that the experimentally accessible scattering cross section exhibits universal Ericson fluctuations, with characteristic properties rooted in the underlying classical field equations.
Knots in a Spinor Bose-Einstein Condensate
Kawaguchi, Yuki; Nitta, Muneto; Ueda, Masahito
2008-01-01
We show that knots of spin textures can be created in the polar phase of a spin-1 Bose-Einstein condensate, and discuss experimental schemes for their generation and probe, together with their lifetime.
Phase coherence length of a Bose-Einstein condensate
Gerbier, F.; Richard, S.; Thywissen, J. H.; Hugbart, M.; Bouyer, P.; Aspect, A.
2002-01-01
We report on the measurement of the momentum distribution of an elongated Bose-Einstein condensate. A broadening of the distribution with increasing temperature is observed, which is clear evidence for phase fluctuations in the sample.
Quantum Evaporation of a Bose-Einstein Condensate
Duine, R. A.; Stoof, H.T.C.
2002-01-01
We show that a Bose-Einstein condensate emits atoms, if either the condensate wave function, or the scattering length of the atoms depends strongly on time. Moreover, the emission process is coherent and atoms can oscillate back and forth between the condensate and the excited states. Inspired by recent experimental results, we present results of simulations of the response of a Bose-Einstein condensate to a very rapid change in the scattering length. The possibility of molecule formation is ...
Semi-classical Dynamics of Superradiant Rayleigh Scattering in a Bose-Einstein Condensate
Müller, J H; Targat, R le; Arlt, J J; Polzik, E S; Hilliard, A J
2016-01-01
Due to its coherence properties and high optical depth, a Bose-Einstein condensate provides an ideal setting to investigate collective atom-light interactions. Superradiant light scattering in a Bose-Einstein condensate is a fascinating example of such an interaction. It is an analogous process to Dicke superradiance, in which an electronically inverted sample decays collectively, leading to the emission of one or more light pulses in a well-defined direction. Through time-resolved measurements of the superradiant light pulses emitted by an end-pumped BEC, we study the close connection of superradiant light scattering with Dicke superradiance. A 1D model of the system yields good agreement with the experimental data and shows that the dynamics results from the structures that build up in the light and matter-wave fields along the BEC. This paves the way for exploiting the atom-photon correlations generated by the superradiance.
Bose-Einstein condensation of the classical axion field in cosmology?
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 GN, 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
Bose-Einstein condensation of the classical axion field in cosmology?
Davidson, Sacha; Elmer, Martin, E-mail: s.davidson@ipnl.in2p3.fr, E-mail: m.elmer@ipnl.in2p3.fr [IPNL, Université de Lyon, Université Lyon 1, CNRS/IN2P3, 4 rue E. Fermi, Villeurbanne cedex, 69622 (France)
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.
Landau damping of transverse quadrupole oscillations of an elongated Bose-Einstein condensate
Guilleumas, Montserrat; Pitaevskii, L. P.
2003-01-01
We study the interaction between low-lying transverse collective oscillations and thermal excitations of an elongated Bose-Einstein condensate by means of perturbation theory. We consider a cylindrically trapped condensate and calculate the transverse elementary excitations at zero temperature by solving the linearized Gross-Pitaevskii equations in two dimensions. We use them to calculate the matrix elements between thermal excited states coupled with the quasi-2D collective modes. The Landau...
On theory of Bose-Einstein condensation of particles with arbitrary integer spin
The Bogoliubov theory of weakly interacting Bose gas is generalized to Bose-Einstein condensates (BEC) of particles with arbitrary integer spin in a magnetic field. On the basis of the Bogoliubov method of quasiaverages, an equation for the condensate wave function is obtained. The ground state properties, thermodynamic stability, and excitation spectra of such BEC are studied. The obtained results are compared to spin-1 Bose condensate. (author)
Bose-Einstein Condensation on a Manifold with Nonnegative Ricci Curvature
Akant, Levent; Ertugrul, Emine; Tapramaz, Ferzan; Turgut, O. Teoman
2013-01-01
The Bose-Einstein condensation for an ideal Bose gas and for a dilute weakly interacting Bose gas in a manifold with nonnegative Ricci curvature is investigated using the heat kernel and eigenvalue estimates of the Laplace operator. The main focus is on the nonrelativistic gas. However, special relativistic ideal gas is also discussed. The thermodynamic limit of the heat kernel and eigenvalue estimates is taken and the results are used to derive bounds for the depletion coefficient. In the ca...
Dynamics of bright matter-wave solitons in inhomogeneous cigar-type Bose-Einstein condensate
Abdullaev, F. Kh.; Gammal, A.; Tomio, L.
2002-01-01
We discuss the possible observation of a new type of standing nonlinear atomic matter wave in the condensate: the nonlinear impurity mode. It is investigated dynamical effects of a bright soliton in Bose-Einstein-condensed (BEC) systems with local space variations of the two-body atomic scattering length. A rich dynamics is observed in the interaction between the soliton and an inhomogeneity. Processes as trapping, reflection and transmission of the bright matter soliton due to the impurity a...
Density engineering of an oscillating soliton/vortex ring in a Bose-Einstein condensate
Shomroni, Itay; Lahoud, Elias; Levy, Shahar; Steinhauer, Jeff
2008-01-01
When two Bose-Einstein condensates (BEC's) collide with high collisional energy, the celebrated matter wave interference pattern results. For lower collisional energies the repulsive interaction energy becomes significant, and the interference pattern evolves into an array of grey solitons. The lowest collisional energy, producing a single pair of solitons, has not been probed. We use density engineering on the healing length scale to produce such a pair of solitons. These solitons then evolv...
Coherent dynamics of Bose-Einstein condensates in high-finesse optical cavities
Horak, Peter; Barnett, Stephen M.; Ritsch, Helmut
1999-01-01
We study the mutual interaction of a Bose-Einstein condensed gas with a single mode of a high-finesse optical cavity. We show how the cavity transmission reflects condensate properties and calculate the self-consistent intra-cavity light field and condensate evolution. Solving the coupled condensate-cavity equations we find that while falling through the cavity, the condensate is adiabatically transfered into the ground state of the periodic optical potential. This allows time dependent non-d...
Slow light and the phase of a Bose-Einstein condensate
Ohberg, P.
2002-01-01
We investigate the propagation of light with ultra low group velocity in a Bose-Einstein condensate where the phase is not uniform. The light is shown to couple strongly to the phase gradient of the condensate. The interaction between the light and the condensate enables us to perform a phase imprinting where the phase of the condensate is imprinted on the light. We illustrate the effect by showing how one can measure the fluctuating phase in an elongated quasicondensate.
Squeezing and Entanglement of Density Oscillations in a Bose-Einstein Condensate.
Wade, Andrew C J; Sherson, Jacob F; Mølmer, Klaus
2015-08-01
The dispersive interaction of atoms and a far-detuned light field allows nondestructive imaging of the density oscillations in Bose-Einstein condensates. Starting from a ground state condensate, we investigate how the measurement backaction leads to squeezing and entanglement of the quantized density oscillations. We show that properly timed, stroboscopic imaging and feedback can be used to selectively address specific eigenmodes and avoid excitation of nontargeted modes of the system. PMID:26296103
Spectrum and thermal fluctuations of a microcavity polariton Bose-Einstein condensate
Sarchi, D.; Savona, V.
2007-01-01
The Hartree-Fock-Popov theory of interacting Bose particles is developed, for modeling exciton-polaritons in semiconductor microcavities undergoing Bose-Einstein condensation. A self-consistent treatment of the linear exciton-photon coupling and of the exciton non-linearity provides a thermal equilibrium description of the collective excitation spectrum, of the polariton energy shifts and of the phase diagram. Quantitative predictions support recent experimental findings.
On a theory of light scattering from a Bose-Einstein condensate
Ezhova, Victoria; Kupriyanov, Dmitriy
2016-01-01
We consider a quantum theory of elastic light scattering from macroscopic atomic sample existing in the Bose-Einstein condensate (BEC) phase. Following to the second quantized formalism we introduce a set of coupled and closed diagram equations for the polariton propagator contributing to the $T$ -matrix and scattering amplitude. Our approach allows to follow important density correction to the quasi-energy structure caused by static interaction and radiation losses associated with incoherent scattering in the case of near resonance excitation.
A molecular Bose-Einstein condensate emerges from a Fermi sea
Greiner, Markus; Regal, Cindy A.; Jin, Deborah S.
2003-01-01
The realization of fermionic superfluidity in a dilute gas of atoms, analogous to superconductivity in metals, is a long-standing goal of ultracold gas research. Beyond being a new example of this fascinating quantum phenomenon, fermionic superfluidity in an atomic gas holds the promise of adjustable interactions and the ability to tune continuously from BCS-type superfluidity to Bose-Einstein condensation (BEC). This crossover between BCS superfluidity of correlated atom pairs in momentum sp...
Vortex-Nucleating Zeeman Resonance in Axisymmetric Rotating Bose-Einstein Condensates
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
Storing flux qubits in the quantum RAM of binary Bose-Einstein condensates
Patton, Kelly R
2012-01-01
We consider the hybrid quantum system of an rf-SQUID interacting via its magnetic field with a two-component Bose-Einstein condensate. It is shown that the effective coupling between the quantized SQUID flux and the atomic hyperfine states scales with the total number of particles in the condensate. We demonstrate that this renders the two-component condensate a practically realizable and rapidly accessible storage and retrieval unit for the quantum information encoded in the flux qubits.
Magnetic Soliton and Soliton Collisions of Spinor Bose-Einstein Condensates in an Optical Lattice
Li, Z. D.; He, P. B.; Li, L.; Liang, J. Q.; Liu, W. M.
2005-01-01
We study the magnetic soliton dynamics of spinor Bose-Einstein condensates in an optical lattice which results in an effective Hamiltonian of anisotropic pseudospin chain. A modified Landau-Lifshitz equation is derived and exact magnetic soliton solutions are obtained analytically. Our results show that the time-oscillation of the soliton size can be controlled in practical experiment by adjusting of the light-induced dipole-dipole interaction. Moreover, the elastic collision of two solitons ...
In pp and panti p collisions at the CERN Intersecting Storage Rings, a directional dependence of the size of the pion-emitting region is observed using Bose-Einstein interference between identical charged pions. The data reveal a substantially larger dimension in the direction parallel to the beam axis than in the transverse direction, indicating a prolate shape of the emission region. For αα interactions, the data are consistent with a spherical shape. (orig.)
Tunneling Dynamics Between Any Two Multi-atomic-molecular Bose-Einstein Condensates
CHEN Chang-Yong; GAO Ke-Lin
2005-01-01
Tunneling dynamics of multi-atomic molecules between any two multi-atomic molecular Bose-Einstein condensates with Feshbach resonance is investigated. It is indicated that the tunneling in the two Bose-Einstein condensates depends not only on the inter-molecular nonlinear interactions and the initial number of molecule in these condensates, but also on the tunneling coupling between them. It is discovered that besides oscillating tunneling current between the multi-atomic molecular condensates, the nonlinear multi-atomic molecular tunneling dynamics sustains a self-locked population imbalance: a macroscopic quantum self-trapping effect. The influence of de-coherence caused by non-condensate molecule on the tunneling dynamics is studied. It is shown that de-coherence suppresses the multi-atomic molecular tunneling.
Dynamics of dark-bright solitons in cigar-shaped Bose-Einstein condensates
Middelkamp, S. [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, 22761 Hamburg (Germany); Chang, J.J.; Hamner, C. [Washington State University, Department of Physics and Astronomy, Pullman, WA 99164 (United States); Carretero-Gonzalez, R. [Nonlinear Physics Group, Escuela Tecnica Superior de Ingenieria Informatica, Departamento de Fisica Aplicada I, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012 Sevilla (Spain); Kevrekidis, P.G., E-mail: kevrekid@gmail.co [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Achilleos, V.; Frantzeskakis, D.J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece); Schmelcher, P. [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, 22761 Hamburg (Germany); Engels, P. [Washington State University, Department of Physics and Astronomy, Pullman, WA 99164 (United States)
2011-01-17
We explore the stability and dynamics of dark-bright (DB) solitons in two-component elongated Bose-Einstein condensates by developing effective one-dimensional vector equations and solving the three-dimensional Gross-Pitaevskii equations. A strong dependence of the oscillation frequency and of the stability of the DB soliton on the atom number of its components is found; importantly, the wave may become dynamically unstable even in the 1D regime. As the atom number in the dark-soliton-supporting component is further increased, spontaneous symmetry breaking leads to oscillatory dynamics in the transverse degrees of freedom. Moreover, the interactions of two DB solitons are investigated with an emphasis on the importance of their relative phases. Experimental results showcasing multiple DB soliton oscillations and a DB-DB collision in a Bose-Einstein condensate consisting of two hyperfine states of {sup 87}Rb confined in an elongated optical dipole trap are presented.
Dai, Chao-Qing; Wang, Deng-Shan; Wang, Liang-Liang; Zhang, Jie-Fang; Liu, W. M.
2011-09-01
We investigate exact nonlinear matter wave functions with odd and even parities in the framework of quasi-two-dimensional Bose-Einstein condensates (BECs) with spatially modulated cubic-quintic nonlinearities and harmonic potential. The existence condition for these exact solutions requires that the minimum energy eigenvalue of the corresponding linear Schrödinger equation with harmonic potential is the cutoff value of the chemical potential λ. The competition between two-body and three-body interactions influences the energy of the localized state. For attractive two-body and three-body interactions, the larger the matter wave order number n, the larger the energy of the corresponding localized state. A linear stability analysis and direct simulations with initial white noise demonstrate that, for the same state (fixed n), increasing the number of atoms can add stability. A quasi-stable ground-state matter wave is also found for repulsive two-body and three-body interactions. We also discuss the experimental realization of these results in future experiments. These results are of particular significance to matter wave management in higher-dimensional BECs.
Unconventional Bose-Einstein Condensations from Spin-Orbit Coupling
ZHOU Xiang-Fa; WU Cong-Jun; Ian Mondragon-Shem
2011-01-01
According to the "no-node" theorem, the many-body ground state wavefunctions of conventional Bose-Einstein condensations (BEC) are positive-definite, thus time-reversal symmetry cannot be spontaneously broken. We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm. We focus on a subtle case ofisotropic Rashba spin-orbit coupling and the spin-independent interaction. In the limit of the weak confining potential, the condensate wavefunctions are frustrated at the Hartree-Fock level due to the degeneracy of the Rashba ring. Quantum zero-point energy selects the spin-spiral type condensate through the "order-from-disorder" mechanism. In a strong harmonic confining trap, the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture. In both cases, time-reversal symmetry is spontaneously broken. These phenomena can be realized in both cold atom systems with artificial spin-orbit couplings generated from atom-laser interactions and exciton condensates in semi-conductor systems.%@@ According to the"no-node"theorem,the many-body ground state wavefunctions of conventional Bose-Einstein condensations(BEC)are positive-definite,thus time-reversal symmetry cannot be spontaneously broken.We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm.We focus on a subtle case of isotropic Rashba spin-orbit coupling and the spin-independent interaction.In the limit of the weak confining potential,the condensate wavefunctions are frustrated at the Hartree-Fork level due to the degeneracy of the Rashba ring.Quantum zero-point energy selects the spin-spiral type condensate through the"order-from-disorder"mechanism.In a strong harmonic confining trap,the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture.In both cases,time-reversal symmetry is spontaneously broken
Elastic scattering of a Bose-Einstein condensate at a potential landscape
We investigate the elastic scattering of Bose-Einstein condensates at shallow periodic and disorder potentials. We show that the collective scattering of the macroscopic quantum object couples to internal degrees of freedom of the Bose-Einstein condensate such that the Bose-Einstein condensate gets depleted. As a precursor for the excitation of the Bose-Einstein condensate we observe wave chaos within a mean-field theory
Elastic scattering of a Bose-Einstein condensate at a potential landscape
Brezinova, Iva; Lode, Axel U. J.; Streltsov, Alexej I.; Cederbaum, Lorenz S.; Alon, Ofir E.; Collins, Lee A.; Schneider, Barry I.; Burgdörfer, Joachim
2013-01-01
We investigate the elastic scattering of Bose-Einstein condensates at shallow periodic and disorder potentials. We show that the collective scattering of the macroscopic quantum object couples to internal degrees of freedom of the Bose-Einstein condensate such that the Bose-Einstein condensate gets depleted. As a precursor for the excitation of the Bose-Einstein condensate we observe wave chaos within a mean-field theory.
Berloff, Natalia G.
2004-01-01
There are several ways to create the vorticity-free solitary waves -- rarefaction pulses -- in condensates: by the process of strongly nonequilibrium condensate formation in a weakly interacting Bose gas, by creating local depletion of the condensate density by a laser beam, and by moving a small object with supercritical velocities. Perturbations created by such waves colliding with vortices are studied in the context of the Gross-Pitaevskii model. We find that the effect of the interactions...
Coupling a single electron to a Bose-Einstein condensate
Balewski, Jonathan B; Gaj, Anita; Peter, David; Büchler, Hans Peter; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman
2013-01-01
The coupling of electrons to matter is at the heart of our understanding of material properties such as electrical conductivity. One of the most intriguing effects is that electron-phonon coupling can lead to the formation of a Cooper pair out of two repelling electrons, the basis for BCS superconductivity. Here we study the interaction of a single localized electron with a Bose-Einstein condensate (BEC) and show that it can excite phonons and eventually set the whole condensate into a collective oscillation. We find that the coupling is surprisingly strong as compared to ionic impurities due to the more favorable 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 comparable to the dimensions of the BEC, namely up to 8 micrometers. 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...
Integrated Mach-Zehnder interferometer for Bose-Einstein condensates
Full text: Quantum mechanical particle-wave duality enables the construction of interferometers for matter waves, which may complement lasers in precision measurement devices such as gravimeters or gyroscopes. This requires the development of atom-optics analogs to beam splitters, phase shifters, and recombiners. Implementing and integrating these elements into a single device has been a long-standing goal. Here we demonstrate a full Mach-Zehnder sequence with trapped Bose-Einstein condensates (BEC) confined on an atom chip (Berrada et al., arXiv:1303.1030). Particle interactions in our BEC matter waves lead to a non-linearity, absent in photon optics. We exploit this interaction to generate a non-classical state with reduced number fluctuations inside the interferometer. Making use of spatially separated wave packets, a controlled phase shift is applied and read out by a nonadiabatic matter-wave recombiner. We demonstrate coherence times a factor of three beyond what is expected for coherent states, highlighting the potential of entanglement as a resource for metrology. Our results pave the way towards integrated quantum-enhanced matter-wave sensors. (author)
The ideal Bose-Einstein gas, revisited
Some questions concerning the ideal Bose-Einstein gas are reviewed and examined further. The bulk behavior including the condensation phenomenon is characterized by the thermodynamical properties, occupations of the states and their fluctuations, and the properties of the density matrices, including the diagonal and off-diagonal long range orders. Particular attention is focused on the difference between the canonical and grand canonical ensembles and a case is made that the latter does not represent any physical system in the condensed region. The properties in a finite region are also examined to study the approach to the bulk limit and secondly to derive the surface properties such as the surface tension (due to the boundary). This is mainly done for the special case of a rectangular parallelopiped (box) for various boundary conditions. The question of the asymptotic behavior of the fluctuations in the occupation of the ground state in the condensed region in the canonical ensemble is examined for these systems. Finally, the local properties near the wall of a half infinite system are calculated and discussed. The surface properties also follow this way and agree with the strictly thermodynamic result. Although it is not intended to be a complete review, it is largely self-contained, with the first section containing the basic formulas and a discussion of some general concepts which will be needed. Especially discussed in detail are the extra considerations that are needed in thermodynamics and statistical mechanics to include the surface properties, and the quantum hierarchy of the density matrices and local conservation laws. In the concluding remarks several problems are mentioned which need further analysis and clarification. (Auth.)
Scattering Length Instability in Dipolar Bose-Einstein Condensates
We predict a new kind of instability in a Bose-Einstein condensate composed of dipolar particles. Namely, a comparatively weak dipole moment can produce a large, negative two-body scattering length that can collapse the Bose-Einstein condensate. To verify this effect, we validate mean-field solutions to this problem using exact, diffusion Monte Carlo methods. We show that the diffusion Monte Carlo energies are reproduced accurately within a mean-field framework if the variation of the s-wave scattering length with the dipole strength is accounted for properly
Impurities in Bose-Einstein Condensates: From Polaron to Soliton.
Shadkhoo, Shahriar; Bruinsma, Robijn
2015-09-25
We propose that impurities in a Bose-Einstein condensate which is coupled to a transversely laser-pumped multimode cavity form an experimentally accessible and analytically tractable model system for the study of impurities solvated in correlated liquids and the breakdown of linear-response theory [corrected]. As the strength of the coupling constant between the impurity and the Bose-Einstein condensate is increased, which is possible through Feshbach resonance methods, the impurity passes from a large to a small polaron state, and then to an impurity-soliton state. This last transition marks the breakdown of linear-response theory. PMID:26451565
Coherently Scattering Atoms from an Excited Bose-Einstein Condensate
Bijlsma, M.J.; Stoof, H.T.C.
1999-01-01
We consider scattering atoms from a fully Bose-Einstein condensed gas. If we take these atoms to be identical to those in the Bose-Einstein condensate, this scattering process is to a large extent analogous to Andreev reflection from the interface between a superconducting and a normal metal. We determine the scattering wave function in both the absence and the presence of a vortex. Our results show a qualitative difference between these two cases that can be understood as due to an Aharonov-...
Production of a Bose Einstein condensate of metastable helium atoms
Santos, F. Pereira Dos; Léonard, J.; Wang, Junmin; Barrelet, C. J.; Perales, F.; Rasel, E.; Unnikrishnan, C. S.; Leduc, M.; Cohen-Tannoudji, C.
2003-04-01
We recently observed a Bose-Einstein condensate in a dilute gas of 4He in the 23S1 metastable state. In this article, we describe the successive experimental steps which led to the Bose-Einstein transition at 4.7 μK: loading of a large number of atoms in a MOT, efficient transfer into a magnetic Ioffé-Pritchard trap, and optimization of the evaporative cooling ramp. Quantitative measurements are also given for the rates of elastic and inelastic collisions, both above and below the transition.
Shock Waves in a Bose-Einstein Condensate
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.
Tunable bistability in hybrid Bose-Einstein condensate optomechanics.
Yasir, Kashif Ammar; Liu, Wu-Ming
2015-01-01
Cavity-optomechanics, a rapidly developing area of research, has made a remarkable progress. A stunning manifestation of optomechanical phenomena is in exploiting the mechanical effects of light to couple the optical degree of freedom with mechanical degree of freedom. In this report, we investigate the controlled bistable dynamics of such hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC) trapped inside high-finesse optical cavity with one moving-end mirror and is driven by a single mode optical field. The numerical results provide evidence for controlled optical bistability in optomechanics using transverse optical field which directly interacts with atoms causing the coupling of transverse field with momentum side modes, exited by intra-cavity field. This technique of transverse field coupling is also used to control bistable dynamics of both moving-end mirror and BEC. The report provides an understanding of temporal dynamics of moving-end mirror and BEC with respect to transverse field. Moreover, dependence of effective potential of the system on transverse field has also been discussed. To observe this phenomena in laboratory, we have suggested a certain set of experimental parameters. These findings provide a platform to investigate the tunable behavior of novel phenomenon like electromagnetically induced transparency and entanglement in hybrid systems. PMID:26035206
Manipulating localized matter waves in multicomponent Bose-Einstein condensates
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.
Effect of a localized impurity on soliton dynamics in the Bose-Einstein condensates
Yang Ru-Shu; Yao Chun-Mei; Wu Zong-Fu
2011-01-01
By using a multiple-scale method, we analytically study the effect of a localized impurity on the soliton dynamics in the Bose-Einstein condensates. It is shown that a dark soliton can be transmitted through a repulsive (or attractive) impurity, while at the position of the localized impurity the soliton can be quasitrapped by the impurity. Additionally, we find that the strength of the localized impurity has an important effect on the dark soliton dynamics. With increasing strength of the localized impurity, the amplitude of the dark soliton becomes bigger, while its width is narrower, and the soliton propagates slower.
A Time-Splitting and Sine Spectral Method for Dynamics of Dipolar Bose-Einstein Condensate
Si-Qi Li
2013-01-01
Full Text Available A two-component Bose-Einstein condensate (BEC described by two coupled a three-dimension Gross-Pitaevskii (GP equations is considered, where one equation has dipole-dipole interaction while the other one has only the usual s-wave contact interaction, in a cigar trap. The time-splitting and sine spectral method in space is proposed to discretize the time-dependent equations for computing the dynamics of dipolar BEC. The singularity in the dipole-dipole interaction brings significant difficulties both in mathematical analysis and in numerical simulations. Numerical results are given to show the efficiency of this method.
Effects of external magnetic trap on two dark solitons of a two-component Bose-Einstein condensate
Hong Li; D. N. Wang
2008-01-01
Two dark solitons are considered in a two-component Bose-Einstein condensate with an external magnetic trap, and effects of the trap potential on their dynamics are investigated by the numerical simulation. The results show that the dark solitons attract, collide and repel periodically in two components as time changes, the time period depends strictly on the initial condition and the potential, and there are obvious self-trapping effects on the two dark solitons.