A Model for Macroscopic Quantum Tunneling of Bose-Einstein Condensate with Attractive Interaction
Institute of Scientific and Technical Information of China (English)
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.
Palpacelli, Silvia; Succi, Sauro
Following an idea first proposed by Penrose in 1996 to explain the problem of quantum state reduction as a gravitational effect, Moroz, Penrose and Tod1 have shown that quantum state reduction due to gravitational interactions could take place in about one second for the case of 1011 nucleons. However, keeping 1011 nucleons together in a quantum macroscopic state does not appear to be feasible as yet. The closest physical system to such a situation is provided by Bose-Einstein condensates (BEC) with attractive interactions. We present numerical simulations of the Schrödinger-Newton equations, which show that an attractive BEC with 103 atoms would yield a decorrelation time of the order of 10-2 seconds. Hence, a "Penrose-like" reduction, induced by BEC attractive interaction instead of gravity, might be observable and possibly monitored in current BEC experiments with attractive interactions.
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
International Nuclear Information System (INIS)
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
Observation of Attractive and Repulsive Polarons in a Bose-Einstein Condensate
DEFF Research Database (Denmark)
Jørgensen, Nils B.; Wacker, Lars; Skalmstang, Kristoffer Theis;
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 unitarity. Our...
Observation of attractive and repulsive polarons in a Bose-Einstein condensate
DEFF Research Database (Denmark)
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...
Accelerated expansion of a universe containing a self-interacting Bose-Einstein gas
Energy Technology Data Exchange (ETDEWEB)
Izquierdo, German; Besprosvany, Jaime, E-mail: german.izquierdo@gmail.co, E-mail: bespro@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Circuito de la Investigacion CientIfica S/N, Ciudad Universitaria, CP 04510, Mexico, Distrito Federal (Mexico)
2010-03-21
Acceleration of the universe is obtained from a model of non-relativistic particles with a short-range attractive interaction, at low enough temperature to produce a Bose-Einstein condensate. Conditions are derived for negative-pressure behavior. In particular, we show that a phantom-accelerated regime at the beginning of the universe solves the horizon problem, consistently with nucleosynthesis.
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
DEFF Research Database (Denmark)
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...
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...
Effects of Interactions on Bose-Einstein Condensation
Smith, Robert P.
2016-01-01
Bose-Einstein condensation is a unique phase transition in that it is not driven by inter-particle interactions, but can theoretically occur in an ideal gas, purely as a consequence of quantum statistics. This chapter addresses the question \\emph{`How is this ideal Bose gas condensation modified in the presence of interactions between the particles?' } This seemingly simple question turns out to be surprisingly difficult to answer. Here we outline the theoretical background to this question a...
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...
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
International Nuclear Information System (INIS)
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
International Nuclear Information System (INIS)
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
Institute of Scientific and Technical Information of China (English)
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.
Bose-Einstein Correlations in charged current muon-neutrino interactions in NOMAD
Zei, R
2004-01-01
Bose-Einstein Correlations in one and two dimensions have been studied in charged current muon-neutrino interaction events collected with NOMAD. In one dimension the Bose-Einstein effect has been analyzed with the Goldhaber and the Kopylov parametrizations. 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 sizes is observed.
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.
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
2016-07-29
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 ^{39}K 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.
Interaction of ring dark solitons with ring impurities in Bose-Einstein condensates
International Nuclear Information System (INIS)
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
Effects of three-body interaction on collective excitation and stability of Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
Peng Ping; Li Guan-Qiang
2009-01-01
This paper investigates the collective excitation and stability of low-dimensional Bose-Einstein condensates with two-and three-body interactions by the variational analysis of the time-dependent Gross-Pitaevskii-Ginzburg equation.The spectrum of the low-energy excitation and the effective potential for the width of the condensate are obtained.The results show that:(i) the repulsive two-body interaction among atoms makes the frequency red-shifted for the internal excitation and the repulsive or attractive three-body interaction always makes it blue-shifted; (ii) the region for the existence of the stable bound states is obtained by identifying the critical value of the two-and three-body interactions.
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
Chavanis, P H
2011-01-01
We develop the suggestion that dark matter could be a Bose-Einstein condensate. We determine the mass-radius relation of a Newtonian self-gravitating Bose-Einstein condensate with short-range interactions described by the Gross-Pitaevskii-Poisson system. We numerically solve the equation of hydrostatic equilibrium describing the balance between the gravitational attraction and the pressure due to quantum effects (Heisenberg's uncertainty principle) and short-range interactions (scattering). We connect the non-interacting limit to the Thomas-Fermi limit. We also consider the case of attractive self-interaction. We compare the exact mass-radius relation obtained numerically with the approximate analytical relation obtained with a Gaussian ansatz. An overall good agreement is found.
Institute of Scientific and Technical Information of China (English)
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.
Coupling between Collective Excitations of a Bose-Einstein Condensate and Modulated Interactions
Institute of Scientific and Technical Information of China (English)
ZHANG Jian; ZHENG Fa-Wei
2008-01-01
@@ We investigate collective excitations of a Bose-Einstein condensate in the presence of temporal modulation of repulsive interactions, and analytically demonstrate that the modulated interaction can drive the condensate to oscillate with the external modulation frequency, and that the interaction couples with the eigen modes of the condensate collective excitations, which was previously considered to be independent of interaction. When the external modulation frequency approaches or is far away from the eigen frequency of the density monopole mode, the condensate shows resonant or beating behaviour.
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...
Institute of Scientific and Technical Information of China (English)
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.
Creation of ^{39}K Bose-Einstein condensates with tunable interaction
DEFF Research Database (Denmark)
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......-species Bose-Einstein condensates consisting of 6×105 87Rb atoms, 2×105 39K atoms and 1×104 41K atoms. The creation of dual-species condensates will be the next experimental milestone. This will allow for the investigation of the interaction within ultracold potassium-rubidium mixtures leading to the creation...
International Nuclear Information System (INIS)
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)
Tunneling dynamics of Bose-Einstein condensates with higher-order interactions in optical lattice
Institute of Scientific and Technical Information of China (English)
Tie Lu; Xue Ju-Kui
2011-01-01
The nonlinear Landau-Zener tunneling and nonlinear Rabi oscillations of Bose-Einstein condensate (BEC) with higher-order atomic interaction between the Bloch bands in an accelerating optical lattice are discussed.Within the two-level model,the tunneling probability of BEC with higher-order atomic interaction between Bloch bands is obtained.We finds that the tunneling rate is closely related to the higher-order atomic interaction.Furthermore,the nonlinear Rabi oscillations of BEC with higher-order atomic interaction between the bands are discussed by imposing a periodic modulation on the level bias.Analytical expressions of the critical higher-order atomic interaction for suppressing/enhancing the Rabi oscillations are obtained.It is shown that the critical value strongly depends on the modulation parameters (i.e.,the modulation amplitude and frequency) and the strength of periodic potential.
Bose-Einstein Condensates in Optical Lattices with Higher-Order Interactions
Institute of Scientific and Technical Information of China (English)
张爱霞; 薛具奎
2012-01-01
The higher-order interactions of Bose-Einstein condensate in multi-dimensional optical lattices are discussed both analytically and numerically.It is demonstrated that the effects of the higher-order atomic interactions on the sound speed and the stabilities of Bloch waves strongly depend on the lattice strength.In the presence of higher-order effects,tighter and high-dimensional lattices are confirmed to be two positive factors for maintaining the system＇s energetic stability,and the dynamical instability of Bloch waves can take place simultaneously with the energetic instability.In addition,we find that the higher-order interactions exhibit a long-range behavior and the long-lived coherent Bloch oscillations in a tilted optical lattice exist.Our results provide an effective way to probe the higher-order interactions in optical lattices.
Institute of Scientific and Technical Information of China (English)
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.
Feedback control of an interacting Bose-Einstein condensate using phase-contrast imaging
Szigeti, Stuart S; Carvalho, Andre R R; Hope, Joseph J
2010-01-01
The linewidth of an atom laser is limited by density fluctuations in the Bose-Einstein condensate (BEC) from which the atom laser beam is outcoupled. In this paper we show that a stable spatial mode for an interacting BEC can be generated using a realistic control scheme that includes the effects of the measurement backaction. This model extends the feedback theory, based on a phase-contrast imaging setup, presented in \\cite{Szigeti:2009}. In particular, it is applicable to a BEC with large interatomic interactions and solves the problem of inadequacy of the mean-field (coherent state) approximation by utilising a fixed number state approximation. Our numerical analysis shows the control to be more effective for a condensate with a large nonlinearity.
Rayleigh surface wave interaction with the 2D exciton Bose-Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
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.
Feedback control of an interacting Bose-Einstein condensate using phase-contrast imaging
Szigeti, S. S.; Hush, M. R.; Carvalho, A. R. R.; Hope, J. J.
2010-10-01
The linewidth of an atom laser is limited by density fluctuations in the Bose-Einstein condensate (BEC) from which the atom laser beam is outcoupled. In this paper we show that a stable spatial mode for an interacting BEC can be generated using a realistic control scheme that includes the effects of the measurement backaction. This model extends the feedback theory, based on a phase-contrast imaging setup, presented by Szigeti, Hush, Carvalho, and Hope [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.80.013614 80, 013614 (2009)]. In particular, it is applicable to a BEC with large interatomic interactions and solves the problem of inadequacy of the mean-field (coherent state) approximation by utilizing a fixed number state approximation. Our numerical analysis shows the control to be more effective for a condensate with a large nonlinearity.
Quantum Statistical Behaviors of Interaction of an Atomic Bose-Einstein Condensate with Laser
Institute of Scientific and Technical Information of China (English)
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.``
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
Primordial Universe with radiation and Bose-Einstein condensate
Alvarenga, F G; Fracalossi, R; Freitas, R C; Gonçalves, S V B; Monerat, G A; Oliveira-Neto, G; Silva, E V Corrêa
2016-01-01
In this work we derive a scenario where the early Universe consists of radiation and the Bose-Einstein condensate. We have included in our analysis the possibility of gravitational self-interaction due to the Bose-Einstein condensate being attractive or repulsive. After presenting the general structure of our model, we proceed to compute the finite-norm wave packet solutions to the Wheeler-DeWitt equation. The behavior of the scale factor is studied by applying the many-worlds interpretation of quantum mechanics. At the quantum level the cosmological model, in both attractive and repulsive cases, is free from the Big Bang singularity.
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...
Mach-Zehnder interferometry with interacting Bose-Einstein condensates in a double-well potential
International Nuclear Information System (INIS)
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
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.
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
International Nuclear Information System (INIS)
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)
Energy Technology Data Exchange (ETDEWEB)
Astier, P.; Autiero, D.; Baldisseri, A.; Baldo-Ceolin, M.; Banner, M.; Bassompierre, G.; Benslama, K.; Besson, N.; Bird, I.; Blumenfeld, B.; Bobisut, F.; Bouchez, J.; Boyd, S.; Bueno, A.; Bunyatov, S.; Camilleri, L.; Cardini, A.; Cattaneo, P.W.; Cavasinni, V. E-mail: vincenzo.cavasinni@pi.infn.it; Cervera-Villanueva, A.; Challis, R.C.; Chukanov, A.; Collazuol, G.; Conforto, G.; Conta, C.; Contalbrigo, M.; Cousins, R.; Daniels, D.; Degaudenzi, H.; Del Prete, T.; De Santo, A.; Dignan, T.; Di Lella, L.; Couto e Silva, E. do; Dumarchez, J.; Ellis, M.; Feldman, G.J.; Ferrari, R.; Ferrere, D.; Flaminio, V.; Fraternali, M.; Gaillard, J.-M.; Gangler, E.; Geiser, A.; Geppert, D.; Gibin, D.; Gninenko, S.; Godley, A.; Gomez-Cadenas, J.-J.; Gosset, J.; Goessling, C.; Gouanere, M.; Grant, A.; Graziani, G.; Guglielmi, A.; Hagner, C.; Hernando, J.; Hubbard, D.; Hurst, P.; Hyett, N.; Iacopini, E.; Joseph, C.; Juget, F.; Kent, N.; Kirsanov, M.; Klimov, O.; Kokkonen, J.; Kovzelev, A.; Krasnoperov, A.; Lacaprara, S.; Lachaud, C.; Lakic, B.; Lanza, A.; La Rotonda, L.; Laveder, M.; Letessier-Selvon, A.; Levy, J.-M.; Linssen, L.; Ljubicic, A.; Long, J.; Lupi, A.; Lyubushkin, V.; Marchionni, A.; Martelli, F.; Mechain, X.; Mendiburu, J.-P.; Meyer, J.-P.; Mezzetto, M.; Mishra, S.R.; Moorhead, G.F.; Naumov, D.; Nedelec, P.; Nefedov, Yu.; Nguyen-Mau, C.; Orestano, D.; Pastore, F.; Peak, L.S.; Pennacchio, E.; Pessard, H.; Petti, R.; Placci, A.; Polesello, G.; Pollmann, D.; Polyarush, A.; Popov, B.; Poulsen, C.; Rebuffi, L.; Rico, J.; Riemann, P.; Roda, C.; Rubbia, A.; Salvatore, F.; Schahmaneche, K.; Schmidt, B.; Schmidt, T.; Sconza, A.; Sevior, M.; Sillou, D.; Soler, F.J.P.; Sozzi, G.; Steele, D.; Stiegler, U.; Stipcevic, M.; Stolarczyk, Th.; Tareb-Reyes, M.; Taylor, G.N.; Tereshchenko, V.; Toropin, A.; Touchard, A.-M.; Tovey, S.N.; Tran, M.-T.; Tsesmelis, E.; Ulrichs, J.; Vacavant, L.; Valdata-Nappi, M.; Valuev, V.; Vannucci, F.; Varvell, K.E.; Veltri, M.; Vercesi, V. [and others
2004-05-10
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{sub G}=1.01{+-}0.05(stat){sup +0.09}{sub -0.06}(sys) fm and for the chaoticity parameter the value {lambda}=0.40{+-}0.03(stat){sup +0.01}{sub -0.06}(sys). Using the Kopylov-Podgoretskii parametrization yields R{sub KP}=2.07{+-}0.04(stat){sup +0.01}{sub -0.14}(sys) fm and {lambda}{sub KP}=0.29{+-}0.06(stat){sup +0.01}{sub -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.
International Nuclear Information System (INIS)
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.)
Energy Technology Data Exchange (ETDEWEB)
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.)
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.
Observation of attractive and repulsive polarons in a Bose-Einstein condensate
DEFF Research Database (Denmark)
Jørgensen, Nils Byg
2016-01-01
(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...
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.
Institute of Scientific and Technical Information of China (English)
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.
Chavanis, Pierre-Henri
2011-01-01
We provide an approximate analytical expression of the mass-radius relation of a Newtonian self-gravitating Bose-Einstein condensate (BEC) with short-range interactions described by the Gross-Pitaevskii-Poisson system. These equations model astrophysical objects such as boson stars and, presumably, dark matter galactic halos. Our study connects the non-interacting case studied by Ruffini & Bonazzola (1969) to the Thomas-Fermi limit studied by B\\"ohmer & Harko (2007). For repulsive short-range interactions (positive scattering lengths), there exists configurations of arbitrary mass but their radius is always larger than a minimum value. For attractive short-range interactions (negative scattering lengths), equilibrium configurations only exist below a maximum mass. Above that mass, the system is expected to collapse and form a black hole. We also study the radius versus scattering length relation for a given mass. We find that stable configurations only exist above a (negative) minimum scattering lengt...
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.
Dynamics and Matter-Wave Solitons in Bose-Einstein Condensates with Two- and Three-Body Interactions
Directory of Open Access Journals (Sweden)
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.
Guo, Jin-Li
2015-01-01
The paper proposes a Bose-Einstein hypernetwork model, and studies evolving mechanisms and topological properties of hyperedge hyperdegrees of the hypernetwork. We analyze the model by using a Poisson process theory and a continuous technique, and give a characteristic equation of hyperedge hyperdegrees of the Bose-Einstein hypernetwork. We obtain the stationary average hyperedge hyperdegree distribution of the hypernetwork by the characteristic equation. The paper first studies topological properties of hyperedge hyperdegrees. Bose-Einstein condensation model can be seen as a special case of this kind of hypernetworks. Condensation degree is proposed, in particular, the condensation of particles can be classified according to the condensation degree.
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...
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...
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.
Nonlinear vortex-phonon interactions in a Bose-Einstein condensate
Mendonça, J. T.; Haas, F.; Gammal, A.
2016-07-01
We consider the nonlinear coupling between an exact vortex solution in a Bose-Einstein condensate and a spectrum of elementary excitations in the medium. These excitations, or Bogoliubov-de Gennes modes, are indeed a special kind of phonons. We treat the spectrum of elementary excitations in the medium as a gas of quantum particles, sometimes also called bogolons. An exact kinetic equation for the bogolon gas is derived, and an approximate form of this equation, valid in the quasi-classical limit, is also obtained. We study the energy transfer between the vortex and the bogolon gas, and establish conditions for vortex instability and damping.
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
MATHEMATICAL ANALYSIS OF THE COLLAPSE IN BOSE-EINSTEIN CONDENSATE
Institute of Scientific and Technical Information of China (English)
Li Xiaoguang; Zhang Jian; Wu Yonghong
2009-01-01
In this article, the authors consider the collapse solutions of Cauchy problem for the nonlinear Schrodinger equation iψt +1/2Δψ-1/2ω2|x|2ψ+ |ψ|2+|ψ|2ψ=0, x∈R2, which models the Bose-Einstein condensate with attractive interactions. The authors establish the lower bound of collapse rate as t→T. Furthermore, the L2-concentration property of the radially symmetric collapse solutions is obtained.
International Nuclear Information System (INIS)
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)
Boundary-Dependent Chaotic Regions for a Bose-Einstein Condensate Interacting with Laser Field
Institute of Scientific and Technical Information of China (English)
ZHU Qian-Quan; HAI Wen-Hua; DENG Hai-Ming
2007-01-01
Spatial chaos of a Bose-Einstein condensate perturbed by a weak laser standing wave and a weak laser S pulse is studied. By using the perturbed chaotic solution we investigate the new type of Melnikov chaotic regions, which depend on an integration constant CQ determined by the boundary conditions. It is shown that when the |c0| values are small, the chaotic region corresponds to small values of laser wave vector k, and the chaotic region for the larger k values is related to the large |c0| values. The result is confirmed numerically by finding the chaotic and regular orbits on the Poincaré section for the two different parameter regions. Thus, for a fixed c0 the adjustment of k from a small value to large value can transform the chaotic region into the regular one or on the contrary, which suggests a feasible method for eliminating or generating Melnikov chaos.
Chaotic behavior of three interacting vortices in a confined Bose-Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
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.
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.
International Nuclear Information System (INIS)
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.
Chavanis, Pierre-Henri
2011-08-01
We provide an approximate analytical expression of the mass-radius relation of a Newtonian self-gravitating Bose-Einstein condensate (BEC) with short-range interactions described by the Gross-Pitaevskii-Poisson system. These equations model astrophysical objects such as boson stars and, presumably, dark matter galactic halos. Our study connects the noninteracting case studied by Ruffini and Bonazzola (1969) to the Thomas-Fermi limit studied by Böhmer and Harko (2007). For repulsive short-range interactions (positive scattering lengths), there exists configurations of arbitrary mass but their radius is always larger than a minimum value. For attractive short-range interactions (negative scattering lengths), equilibrium configurations only exist below a maximum mass. Above that mass, the system is expected to collapse and form a black hole. We also study the radius versus scattering length relation for a given mass. We find that equilibrium configurations only exist above a (negative) minimum scattering length. Our approximate analytical solution, based on a Gaussian ansatz, provides a very good agreement with the exact solution obtained by numerically solving a nonlinear differential equation representing hydrostatic equilibrium. Our analytical treatment is, however, easier to handle and permits one to study the stability problem, and derive an expression of the pulsation period, by developing an analogy with a simple mechanical problem.
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
Institute of Scientific and Technical Information of China (English)
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
International Nuclear Information System (INIS)
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 ...
Institute of Scientific and Technical Information of China (English)
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.
Vortex dynamics in cubic-quintic Bose-Einstein condensates
Mithun, T.; Porsezian, K.; Dey, Bishwajyoti
2013-07-01
We study vortex dynamics in a trapped Bose-Einstein condensate with tunable two- and three-body interactions. The dynamics is governed by two-dimensional cubic-quintic Gross-Pitaevskii equation. A time-dependent variational method has been used to obtain critical rotational frequency and surface mode frequency analytically and are compared with numerical simulation results. An imaginary time propagation method and Crank-Nicolson scheme for discretization have been used for numerical simulation. The numerically calculated average value of the angular momentum per particle shows very clearly its dynamical relation with the time development of the vortex formation. The rotational frequency dependence of the variation of average value of the angular momentum per particle with time shows that vortices form much faster in time for higher rotational frequency. Similarly, the vortex forms much faster in time with an increase of the strength of the repulsive three-body interaction. The simulation of the vortex lattice formation in the condensate shows that the presence of the three-body interactions does not alter the vortex lattice pattern but it helps in the shape deformations of the condensate thereby leading to vortex lattice formation. Likewise, the three-body interactions enable the vortex lattice formation in Bose-Einstein condensates even with attractive two-body interactions and in purely quintic BEC.
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.
Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices
Institute of Scientific and Technical Information of China (English)
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.
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
International Nuclear Information System (INIS)
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
Energy Technology Data Exchange (ETDEWEB)
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
International Nuclear Information System (INIS)
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
Sandin, P; Gulliksson, M; Smyrnakis, J; Magiropoulos, M; Kavoulakis, G M
2016-01-01
Motivated by numerous experiments on Bose-Einstein condensed atoms which have been performed in tight trapping potentials of various geometries (elongated and/or toroidal/annular), we develop a general method which allows us to reduce the corresponding three-dimensional Gross-Pitaevskii equation for the order parameter into an effectively one-dimensional equation, taking into account the interactions (i.e., treating the width of the transverse profile variationally) and the curvature of the trapping potential. As an application of our model we consider atoms which rotate in a toroidal trapping potential. We evaluate the state of lowest energy for a fixed value of the angular momentum within various approximations of the effectively one-dimensional model and compare our results with the full solution of the three-dimensional problem, thus getting evidence for the accuracy of our model.
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
International Nuclear Information System (INIS)
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…
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
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.
Bose-Einstein condensates in atomic gases: simple theoretical results
International Nuclear Information System (INIS)
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
International Nuclear Information System (INIS)
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.
Entanglement Properties in Two-Component Bose-Einstein Condensate
Jiang, Di-You
2016-10-01
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.
Two scales in Bose-Einstein correlations
Energy Technology Data Exchange (ETDEWEB)
Khoze, V.A.; Ryskin, M.G. [University of Durham, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Petersburg Nuclear Physics Institute, NRC ' Kurchatov Institute' , Gatchina, Saint Petersburg (Russian Federation); Martin, A.D. [University of Durham, Institute for Particle Physics Phenomenology, Durham (United Kingdom); Schegelsky, V.A. [Petersburg Nuclear Physics Institute, NRC ' Kurchatov Institute' , Gatchina, Saint Petersburg (Russian Federation)
2016-04-15
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' parametrisation ansatz. We discuss the expected energy, charged multiplicity and transverse momentum of the pair (that is, √(s), N{sub ch}, k{sub t}) behaviour of both the small and the large size components. (orig.)
Dark Lump Excitations in Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
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.
Bose Einstein condensation of the classical axion field in cosmology?
Davidson, Sacha
2013-01-01
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. Using classical equations of motion during linear structure formation, we explore whether "gravitational thermalisation" can drive axions to a bose einstein condensate. At linear order in G_N, we interpret that the principle activities of gravity are to expand the Universe and grow density fluctuations. From the anisotropic stress, we estimate a short dissipation scale for axions which does not confirm previous estimates of their gravitational thermalisation rate.
Investigating tunable KRb gases and Bose-Einstein condensates
DEFF Research Database (Denmark)
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
Institute of Scientific and Technical Information of China (English)
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.
Transition of a mesoscopic bosonic gas into a Bose-Einstein condensat
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.
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.
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 ...
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.
Scalar field as a Bose-Einstein condensate?
International Nuclear Information System (INIS)
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?
Energy Technology Data Exchange (ETDEWEB)
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.
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.
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...
Dynamic Analysis for Bose-Einstein Condensation in Quantum Cavity
Institute of Scientific and Technical Information of China (English)
ZHANG Li; WANG Cheng; LI Yan-Min; WANG Jin-Fang
2005-01-01
For the two-level atoms system interacting with single-mode active field in a quantum cavity, the dynamics of the Bose-Einstein Condensation (BEC) is analyzed using an ordinary method suggested by authors to solve the system of Schrodinger representation in the Heisenberg representation. The wave function of the atoms is given. The stability factor determining the BEC and the selection rules of the quantum transition are solved.
Modulated amplitude waves in Bose-Einstein condensates
International Nuclear Information System (INIS)
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
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...
Spectroscopic Test of Bose-Einstein Statistics for Photons
International Nuclear Information System (INIS)
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.
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.
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.
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.
Institute of Scientific and Technical Information of China (English)
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...
International Nuclear Information System (INIS)
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.
Levitating soliton of the Bose-Einstein condensate
Vysotina, N. V.; Rosanov, N. N.
2016-07-01
We have proposed a mechanical model that corresponds to the Newton equation for describing the dynamics of an oscillon, viz., a soliton-like cluster of the Bose-Einstein condensate (with atomic attraction) placed above an oscillating atomic mirror in a uniform gravitational field. The model describes the stochastic Fermi acceleration and periodic, quasi-periodic, and chaotic motion of the oscillon center, as well as hysteresis phenomena in the case of a slow variation of mirror oscillation frequency, which are in good agreement with the results obtained using the Gross-Pitaevskii equation.
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.
Number-conserving master equation theory for a dilute Bose-Einstein condensate
Schelle, Alexej; 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 condensate formation, and derive a condition under which the unique equilibrium steady state of a dilute, weakly interacting Bose-Einstein condensate is given by a Gibbs-Boltzmann thermal state of $N$ non-interacting atoms.
Atomic Tunnelling Dynamics of Two Squeezed Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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.
Chaos in a Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
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.
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
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.
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
Energy Technology Data Exchange (ETDEWEB)
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)
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
Behaviour of Rotating Bose-Einstein Condensates Under Shrinking
Institute of Scientific and Technical Information of China (English)
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].
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 ...
Scalar Field as a Bose-Einstein Condensate?
Castellanos, Elías; Núñez, Darío
2013-01-01
We present a flat space analogy between a classical scalar field with a self-interacting potential and a Bose-Einstein condensate (BEC). In particular, we reduce the Klein-Gordon equation, governing the dynamics of the scalar field, to a Gross-Pitaevskii--like equation (GPE), governing the dynamics of BEC's. Moreover, the introduction of a curved background spacetime endows, in a natural way, the resulting GPE-like equation with an explicit confinement potential. Additionally, Thomas-Fermi approximation is applied to the 3-dimensional version of this GPE, in order to calculate some thermodynamical properties of the self-interacting scalar field system.
Observation of interference between two molecular Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
Kohstall, C; Riedl, S; Sanchez Guajardo, E R; Sidorenkov, L A; Hecker Denschlag, J; Grimm, R, E-mail: christoph.kohstall@uibk.ac.at [Institut fuer Experimentalphysik und Zentrum fuer Quantenphysik, Universitaet Innsbruck, 6020 Innsbruck (Austria)
2011-06-15
We have observed the interference between two Bose-Einstein condensates of weakly bound Feshbach molecules of fermionic {sup 6}Li atoms. Two condensates are prepared in a double-well trap and, after release from this trap, overlap in expansion. We detect a clear interference pattern that unambiguously demonstrates the de Broglie wavelength of molecules. We verify that only the condensate fraction shows interference. With increasing interaction strength, the pattern vanishes because elastic collisions during overlap remove particles from the condensate wave function. For strong interaction, the condensates do not penetrate each other as they collide hydrodynamically.
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.
Entanglement generation in quantum networks of Bose-Einstein condensates
Pyrkov, Alexey N
2013-01-01
Two component (spinor) Bose-Einstein condensates (BECs) are considered as the nodes of an interconnected quantum network. Unlike standard single-system qubits, in a BEC the quantum information is duplicated in a large number of identical bosonic particles, thus can be considered to be a "macroscopic" qubit. One of the difficulties with such a system is how to effectively interact such qubits together in order to transfer quantum information and create entanglement. Here we propose a scheme of cavities containing spinor BECs coupled by optical fiber in order to achieve this task. We discuss entanglement generation and quantum state transfer between nodes using such macroscopic BEC qubits.
Entanglement generation in quantum networks of Bose-Einstein condensates
Pyrkov, Alexey N.; Byrnes, Tim
2013-09-01
Two component (spinor) Bose-Einstein condensates (BECs) are considered as the nodes of an interconnected quantum network. Unlike standard single-system qubits, in a BEC the quantum information is duplicated in a large number of identical bosonic particles, thus can be considered to be a ‘macroscopic’ qubit. One of the difficulties with such a system is how to effectively interact such qubits together in order to transfer quantum information and create entanglement. Here we propose a scheme of cavities containing spinor BECs coupled by optical fiber in order to achieve this task. We discuss entanglement generation and quantum state transfer between nodes using such macroscopic BEC qubits.
A Rotating Bose-Einstein Condensation in a Toroidal Trap
Institute of Scientific and Technical Information of China (English)
文渝川; 张鹏鸣; 李师杰
2011-01-01
We have studied the ground state configurations of a rotating Bose-Einstein condensation in a toroidal trap as the radius of the central Ganssian potentiaJ expands adiabatically. Firstly, we observe that the vortices are devoured successively into the central hole of the condensate to form a giant vortex as the radius of the trap expands. When all the pre-existing vortices are absorbed, the angular momentum of the system still increase as the radius of the ganssian potential enlarges. When increasing the interaction strength, we find that more singly quantized vortices are squeezed into the condensate, but the giant vortex does not change.
Stability of self-gravitating Bose-Einstein condensates
Schroven, Kris; List, Meike; Lämmerzahl, Claus
2015-12-01
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.
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
International Nuclear Information System (INIS)
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
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.
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.
Quantum Effects of Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
YU Zhao-Xian; JIAO Zhi-Yong; SUN Jin-Zuo
2004-01-01
In this paper,we study quadrature squeezings of two Bose-Einstein condensates with collision and nonclassical properties of pair entanglement in four wave mixing in Bose-Einstein condensates.With the aid of a numerical method,we find that the two modes(pair entanglement modes)a1 and a2 may exhibit quadrature squeezing,in which they are affected by the initial phase.It is shown that the two pump modes exhibit the same super-Poissonian distribution.The analysis for the mode-mode correlation shows that there always exists a violation of the Cauchy-Schwartz inequality,which means that correlation between the two pump modes is nonclassical.
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.
Astrophysical Bose-Einstein condensates and superradiance
Kühnel, Florian; Rampf, Cornelius
2014-11-01
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 an "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 occurrence and estimate its strength. Our investigations might give an observational handle to phenomenologically constrain Bose-Einstein condensates.
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.
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...
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...
Parametric amplification of matter waves in dipolar spinor Bose-Einstein condensates
DEFF Research Database (Denmark)
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...
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
DEFF Research Database (Denmark)
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 ...
Integrated Mach-Zehnder interferometer for Bose-Einstein condensates.
Berrada, T; van Frank, S; Bücker, R; Schumm, T; Schaff, J-F; Schmiedmayer, J
2013-01-01
Particle-wave duality enables the construction of interferometers for matter waves, which complement optical interferometers in precision measurement devices. This requires the development of atom-optics analogues to beam splitters, phase shifters and recombiners. 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 confined on an atom chip. Particle interactions in our Bose-Einstein condensate matter waves lead to a nonlinearity, absent in photon optics. We exploit it to generate a non-classical state having reduced number fluctuations inside the interferometer. Making use of spatially separated wave packets, a controlled phase shift is applied and read out by a non-adiabatic 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 for integrated quantum-enhanced matter-wave sensors. PMID:23804159
Stability of Two-Component Bose-Einstein Condensates in Bessel Optical Lattices
Institute of Scientific and Technical Information of China (English)
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.
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.
Photon condensation: A new paradigm for Bose-Einstein condensation
Rajan, Renju; Ramesh Babu, P.; Senthilnathan, K.
2016-10-01
Bose-Einstein condensation is a state of matter known to be responsible for peculiar properties exhibited by superfluid Helium-4 and superconductors. Bose-Einstein condensate (BEC) in its pure form is realizable with alkali atoms under ultra-cold temperatures. In this paper, we review the experimental scheme that demonstrates the atomic Bose-Einstein condensate. We also elaborate on the theoretical framework for atomic Bose-Einstein condensation, which includes statistical mechanics and the Gross-Pitaevskii equation. As an extension, we discuss Bose-Einstein condensation of photons realized in a fluorescent dye filled optical microcavity. We analyze this phenomenon based on the generalized Planck's law in statistical mechanics. Further, a comparison is made between photon condensate and laser. We describe how photon condensate may be a possible alternative for lasers since it does not require an energy consuming population inversion process.
Critical rotation of an anharmonically trapped Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
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.
Transport of Bose-Einstein condensates through two dimensional cavities
International Nuclear Information System (INIS)
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
International Nuclear Information System (INIS)
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.
Quantum filaments in dipolar Bose-Einstein condensates
Wächtler, F.; Santos, L.
2016-06-01
Collapse in dipolar Bose-Einstein condensates may be arrested by quantum fluctuations. Due to the anisotropy of the dipole-dipole interactions, the dipole-driven collapse induced by soft excitations is compensated by the repulsive Lee-Huang-Yang contribution resulting from quantum fluctuations of hard excitations, in a similar mechanism as that recently proposed for Bose-Bose mixtures. The arrested collapse results in self-bound filamentlike droplets, providing an explanation for the intriguing results of recent dysprosium experiments. Arrested instability and droplet formation are general features directly linked to the nature of the dipole-dipole interactions, and should hence play an important role in all future experiments with strongly dipolar gases.
Thermalization and Bose-Einstein Condensation in Overpopulated Glasma
Energy Technology Data Exchange (ETDEWEB)
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.
Thermalization and Bose-Einstein Condensation in Overpopulated Glasma
International Nuclear Information System (INIS)
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
Kinetics of Bose-Einstein Condensation in a Trap
Gardiner, C W; Ballagh, R J; Davis, M J
1997-01-01
The formation process of a Bose-Einstein condensate in a trap is described using a master equation based on quantum kinetic theory, which can be well approximated by a description using only the condensate mode in interaction with a thermalized bath of noncondensate atoms. A rate equation of the form n = 2W(n)[(1-exp((mu_n - mu)/kT))n + 1] is derived, in which the difference between the condensate chemical potential mu_n and the bath chemical potential mu gives the essential behavior. Solutions of this equation, in conjunction with the theoretical description of the process of evaporative cooling, give a characteristic latency period for condensate formation and appear to be consistent with the observed behavior of both rubidium and sodium condensate formation.
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.
Energy Technology Data Exchange (ETDEWEB)
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.
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...
Confinement versus Bose-Einstein condensation
Langfeld, K
2004-01-01
The deconfinement phase transition at high baryon densities and low temperatures evades a direct investigation by means of lattice gauge calculations. In order to make this regime of QCD accessible by computer simulations, two proposal are made: (i) A Lattice Effective Theory (LET) is designed which incorporates gluon and diquark fields. The deconfinement transition takes place when the diquark fields undergo Bose-Einstein condensation. (ii) Rather than using eigenstates of the particle number operator, I propose to perform simulations for a fixed expectation value of the baryonic Noether current. This approach changes the view onto the finite density regime, but evades the sign and overlap problems. The latter proposal is exemplified for the LET: Although the transition from the confinement to the condensate phase is first order in the coupling constant space at zero baryon densities, the transition at finite densities appears to be a crossover.
Exactly solvable models for multiatomic molecular Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
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)
Measurements of Bose-Einstein correlations with the ATLAS detector
Sykora, Ivan; The ATLAS collaboration
2015-01-01
The Bose-Einstein correlations provide a unique opportunity for detailed understanding of space-time characteristics of the hadronization region, for determining the size and shape of the source from which particles are emitted and for interpreting quark confinement effects. The correlations lead to enhancement in production of identical bosons that are close in phase space. The ATLAS collaboration has performed a measurement of Bose-Einstein correlations of pairs of charged particles with transverse momentum greater than 100 MeV in p-p collisions at 900 GeV and 7 TeV. Bose-Einstein correlation parameters are investigated up to very high charged-particle multiplicities. The dependence of the Bose-Einstein correlation parameters on the average transverse momentum per pair is also investigated.
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.
Bose-Einstein condensation of the classical axion field in cosmology?
International Nuclear Information System (INIS)
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
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?
Energy Technology Data Exchange (ETDEWEB)
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.
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 ...
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...
Vortex-Nucleating Zeeman Resonance in Axisymmetric Rotating Bose-Einstein Condensates
International Nuclear Information System (INIS)
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
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.
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.
Observation of the supersolid stripe phase in spin-orbit coupled Bose-Einstein condensates
Li, Junru; Huang, Wujie; Burchesky, Sean; Shteynas, Boris; Top, Furkan Çağrı; Jamison, Alan O; Ketterle, Wolfgang
2016-01-01
Supersolidity is an intriguing concept. It combines the property of superfluid flow with the long-range spatial periodicity of solids, two properties which are often mutually exclusive. The original discussion of quantum crystals and supersolidity focuses on solid Helium-4 where it was predicted that vacancies could form dilute weakly interacting Bose-Einstein condensates. In this system, direct observation of supersolidity has been elusive. The concept of supersolidity was then generalized to include other superfluid systems which break the translational symmetry of space. One of such systems is a Bose-Einstein condensate with spin-orbit coupling which has a supersolid stripe phase. Despite several recent studies of this system, the stripe phase has not been observed. Here we report the direct observation of the predicted density modulation of the stripe phase using Bragg reflection. Our work establishes a system with unique symmetry breaking properties. Of future interest is further spatial symmetry breakin...
Dynamics of dark-bright solitons in cigar-shaped Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
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.
Tunneling Dynamics Between Any Two Multi-atomic-molecular Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
DUAN Ya-Fan; XU Zhen; QIAN Jun; SUN Jian-Fang; JIANG Bo-Nan; HONG Tao
2011-01-01
We numerically analyze the dynamic behavior of Bose-Einstein condensate (BEC) in a one-dimensional disordered potential before it completely loses spatial quantum coherence. We find that both the disorder statistics and the atom interactions produce remarkable effects on localization. We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization, showing a counter-intuitive step-wise phase but not a thoroughly randomized phase. Although the condensates as a whole show less flow and expansion, the currents between adjacent phase steps retain strong time dependence. Thus we show explicitly that the localization of a finite size Bose-Einstein condensate is a dynamic equilibrium state.%We numerically analyze the dynamic behavior of Bose-Einstein condensate (BEC) in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and the atom interactions produce remarkable effects on localization.We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization,showing a counter-intuitive step-wise phase but not a thoroughly randomized phase.Although the condensates as a whole show less flow and expansion,the currents between adjacent phase steps retain strong time dependence.Thus we show explicitly that the localization of a finite size Bose-Einstein condensate is a dynamic equilibrium state.In nature,disordered systems exist more generally than periodic ones,because impurities and defects are always present,and disorder is indeed an intrinsic property of all real systems.Although sometimes the strength of disorder is much smaller than the chemical potential of a system,it still produces remarkable effects in the system.
Unconventional Bose-Einstein Condensations from Spin-Orbit Coupling
Institute of Scientific and Technical Information of China (English)
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
Bose-Einstein condensation of plexcitons
Rodriguez, S R K; Rivas, J Gomez
2013-01-01
Bosons (particles with integer spin) above a critical density to temperature ratio may macroscopically populate the ground state of a system, in an effect known as Bose-Einstein Condensation (BEC). The observation of BEC in dilute atomic gases was a great triumph of modern physics, a task requiring nK cooling of atoms. Following these demonstrations, a quest for lighter bosons enabling BEC at higher temperatures came to light. Photons in a microcavity were destined to fulfil this quest. Their coupling to semiconductor excitons allowed the condensation of exciton-polaritons at a few K in solid-state, and the condensation of photons was later observed in a liquid-state dye at room-temperature. Distinctly, one of the most actively studied excitations in condensed matter, surface plasmon polaritons - collective oscillations of conduction electrons in metals -, has never been shown or predicted to exhibit BEC. The strong radiative and Ohmic losses in metals, together with the lack of a suitable (e.g. harmonic) pot...
Elastic scattering of a Bose-Einstein condensate at a potential landscape
International Nuclear Information System (INIS)
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.
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...
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...
Scattering Length Instability in Dipolar Bose-Einstein Condensates
International Nuclear Information System (INIS)
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-...
Space-time curvature signatures in Bose-Einstein condensates
Matos, Tonatiuh; Gomez, Eduardo
2015-05-01
We derive a generalized Gross-Pitaevski (GP) equation for a Bose Einstein Condensate (BEC) immersed in a weak gravitational field starting from the covariant Complex Klein-Gordon field in a curved space-time. We compare it with the traditional GP equation where the gravitational field is added by hand as an external potential. We show that there is a small difference of order gz/c2 between them that could be measured in the future using Bose-Einstein Condensates. This represents the next order correction to the Newtonian gravity in a curved space-time.
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.
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.
Castellanos, Elias
2012-01-01
We deduce the relation between the critical temperature associated to the U(1) symmetry breaking of scalar fields with one--loop correction potential immersed in a thermal bath, and the condensation temperature of the aforementioned system in the thermodynamic limit, within the semiclassical approximation for a weakly interacting bosonic gas with a positive coupling constant. Additionally, we show that the shift in the condensation temperature caused by the coupling constant is independent of the thermal bath.
Directory of Open Access Journals (Sweden)
Leilei Jia
2014-01-01
Full Text Available By using the bifurcation theory of dynamical systems, we present the exact representation and topological classification of coherent matter waves in Bose-Einstein condensates (BECs, such as solitary waves and modulate amplitude waves (MAWs. The existence and multiplicity of such waves are determined by the parameter regions selected. The results show that the characteristic of coherent matter waves can be determined by the “angular momentum” in attractive BECs while for repulsive BECs; the waves of the coherent form are all MAWs. All exact explicit parametric representations of the above waves are exhibited and numerical simulations support the result.
Stationary and nonstationary fluid flow of a bose-einstein condensate through a penetrable barrier.
Engels, P; Atherton, C
2007-10-19
We experimentally study the fluid flow induced by a broad, penetrable barrier moving through an elongated dilute gaseous Bose-Einstein condensate. The barrier is created by a laser beam swept through the condensate, and the resulting dipole potential can be either attractive or repulsive. We examine both cases and find regimes of stable and unstable fluid flow: At slow speeds of the barrier, the fluid flow is steady due to the superfluidity of the condensate. At intermediate speeds, we observe an unsteady regime in which the condensate gets filled with dark solitons. At faster speeds, soliton formation completely ceases, and a remarkable absence of excitation in the condensate is seen again.
Effect of a localized impurity on soliton dynamics in the Bose-Einstein condensates
Institute of Scientific and Technical Information of China (English)
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
Directory of Open Access Journals (Sweden)
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
Institute of Scientific and Technical Information of China (English)
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.
Indian Academy of Sciences (India)
M Cozzini
2006-01-01
The collective modes of a rotating Bose-Einstein condensate confined in an attractive quadratic plus quartic trap are investigated. Assuming the presence of a large number of vortices we apply the diffused vorticity approach to the system. We then use the sum rule technique for the calculation of collective frequencies, comparing the results with the numerical solution of the linearized hydrodynamic equations. Numerical solutions also show the existence of low-frequency multipole modes which are interpreted as vortex oscillations.
Bose-Einstein correlation within the framework of hadronic mechanics
International Nuclear Information System (INIS)
The Bose-Einstein correlation is the phenomenon in which protons and antiprotons collide at extremely high energies; coalesce one into the other resulting into the fireball of finite dimension. They annihilate each other and produces large number of mesons that remain correlated at distances very large compared to the size of the fireball. It was believed that Einstein’s special relativity and relativistic quantum mechanics are the valid frameworks to represent this phenomenon. Although, these frameworks are incomplete and require arbitrary parameters (chaoticity) to fit the experimental data which are prohibited by the basic axioms of relativistic quantum mechanics, such as that for the vacuum expectation values. Moreover, correlated mesons can not be treated as a finite set of isolated point-like particles because it is non-local event due to overlapping of wavepackets. Therefore, the Bose-Einstein correlation is incompatible with the axiom of expectation values of quantum mechanics. In contrary, relativistic hadronic mechanics constructed by Santilli allows an exact representation of the experimental data of the Bose-Einstein correlation and restore the validity of the Lorentz and Poincare symmetries under nonlocal and non-Hamiltonian internal effects. Further, F. Cardone and R. Mignani observed that the Bose-Einstein two-point correlation function derived by Santilli is perfectly matched with experimental data at high energy
Magnon Bose-Einstein condensation at inhomogeneous conditions
International Nuclear Information System (INIS)
The Spin Supercurrent and Bose-Einstein condensation of magnons, similar to an atomic BEC, was discovered in superfluid 3He-B, which is characterized by absolute purity. Later this phenomena were observed in a few magnetically ordered materials with different types of impurities. In this article we will review the properties of magnon BEC in a presence of impurities and defects
Symmetry-assisted vorticity control in Bose-Einstein condensates
Pérez-García, Víctor M.; García-March, Miguel A.; Ferrando, Albert
2006-01-01
Using group-theoretical methods and numerical simulations we show how to act on the topological charge of individual vortices in Bose-Einstein condensates by using control potentials with appropriate discrete symmetries. As examples of our methodology we study charge inversion and vortex erasing by acting on a set of control laser gaussian beams generating optical dipole traps.
Bose-Einstein condensates: BECs from the fridge
Friedrich, Bretislav
2009-10-01
Large ensembles of atoms can be buffer-gas loaded into a magnetic trap and further evaporatively cooled all the way down to quantum degeneracy. The approach has now been shown to provide an alternative - and potentially general - route to Bose-Einstein condensation.
Bose-Einstein correlation within the framework of hadronic mechanics
Energy Technology Data Exchange (ETDEWEB)
Burande, Chandrakant S. [Vilasrao Deshmukh College of Engineering and Technology, Mouda, India-441104, Email: csburande@gmail.com (India)
2015-03-10
The Bose-Einstein correlation is the phenomenon in which protons and antiprotons collide at extremely high energies; coalesce one into the other resulting into the fireball of finite dimension. They annihilate each other and produces large number of mesons that remain correlated at distances very large compared to the size of the fireball. It was believed that Einstein’s special relativity and relativistic quantum mechanics are the valid frameworks to represent this phenomenon. Although, these frameworks are incomplete and require arbitrary parameters (chaoticity) to fit the experimental data which are prohibited by the basic axioms of relativistic quantum mechanics, such as that for the vacuum expectation values. Moreover, correlated mesons can not be treated as a finite set of isolated point-like particles because it is non-local event due to overlapping of wavepackets. Therefore, the Bose-Einstein correlation is incompatible with the axiom of expectation values of quantum mechanics. In contrary, relativistic hadronic mechanics constructed by Santilli allows an exact representation of the experimental data of the Bose-Einstein correlation and restore the validity of the Lorentz and Poincare symmetries under nonlocal and non-Hamiltonian internal effects. Further, F. Cardone and R. Mignani observed that the Bose-Einstein two-point correlation function derived by Santilli is perfectly matched with experimental data at high energy.
Bose-Einstein condensation in a gas of sodium atoms
K.B. Davis; M.O. Mewes; M.R. Andrews; N.J. van Druten; D.S. Durfee; D.M. Kurn; W. Ketterle
1995-01-01
We have observed Bose-Einstein condensation of sodium atoms. The atoms were trapped in a novel trap that employed both magnetic and optical forces. Evaporative cooling increased the phase-space density by 6 orders of magnitude within seven seconds. Condensates contained up to 5 x 105 atoms at densit
Interference of an array of independent Bose-Einstein condensates
Hadzibabic, Z; Bretin, V; Stock, S; Battelier, Baptiste; Bretin, Vincent; Hadzibabic, Zoran; Proxy, Jean Dalibard; Stock, Sabine; ccsd-00001592, ccsd
2004-01-01
We have observed high-contrast matter wave interference between 30 Bose-Einstein condensates with uncorrelated phases. Interference patterns were observed after independent condensates were released from a one-dimensional optical lattice and allowed to expand and overlap. This initially surprising phenomenon is explained with a simple theoretical model which generalizes the analysis of the interference of two independent condensates.
A fresh look at Bose-Einstein correlations
International Nuclear Information System (INIS)
Recent experimental data on Bose-Einstein (BE) correlations between identical bosons are reviewed, and new results concerning the interpretation of the BE enhancement are discussed. In particular, it is emphasized that the classical interpretation of the correlation function in terms of the space-time distribution of particle production points cannot be directly applied to particle production in high energy reactions
Dynamical Properties of a Rotating Bose-Einstein Condensate
Kling, Sebastian; Pelster, Axel
2007-01-01
Within a variational approach to solve the Gross-Pitaevskii equation we investigate dynamical properties of a rotating Bose-Einstein condensate which is confined in an anharmonic trap. In particular, we calculate the eigenfrequencies of low-energy excitations out of the equilibrium state and the aspect ratio of the condensate widths during the free expansion.
A single electron in a Bose-Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
Balewski, Jonathan Benedikt
2014-02-20
This thesis deals with the production and study of Rydberg atoms in ultracold quantum gases. Especially a single electron in a Bose-Einstein condensate can be realized. This new idea, its experimental realization and theoretical description, as well as the development of application probabilities in a manifold of fields form the main topic of this thesis.
Method for monopole creation in spinor Bose-Einstein condensates
Chang, D. E.
2002-01-01
We present a method for creating a monopole in an antiferromagnetic spin-1 Bose-Einstein condensate. The required phase engineering of the multicomponent condensate is achieved using light shifts, which depend on both the magnetic substate m_F and polarization of the incident laser beam.
Spontaneous emission of polaritons from a Bose-Einstein condensate
Marzlin, Karl-Peter; Zhang, Weiping
1999-01-01
We study the spontaneous emission of a partially excited Bose-Einstein condensate composed of two-level atoms. The formation of polaritons induced by the ground-state part of the condensate leads to an avoided crossing in the photon spectrum. This avoided crossing acts similarly to a photonic band gap and modifies the spontaneous emission rate.
How Does a Dipolar Bose-Einstein Condensate Collapse?
Bohn, J. L.; Wilson, R. M.; Ronen, S.
2008-01-01
We emphasize that the macroscopic collapse of a dipolar Bose-Einstein condensate in a pancake-shaped trap occurs through local density fluctuations, rather than through a global collapse to the trap center. This hypothesis is supported by a recent experiment in a chromium condensate.
Scattering of atoms on a Bose-Einstein condensate
Poulsen, Uffe V.; Molmer, Klaus
2002-01-01
We study the scattering properties of a Bose-Einstein condensate held in a finite depth well when the incoming particles are identical to the ones in the condensate. We calculate phase shifts and corresponding transmission and reflection coefficients, and we show that the transmission times can be negative, i.e., the atomic wavepacket seemingly leaves the condensate before it arrives.
Fully permanent magnet atom chip for Bose-Einstein condensation
T. Fernholz; R. Gerritsma; S. Whitlock; I. Barb; R.J.C. Spreeuw
2008-01-01
We describe a proof-of-principle experiment on a fully permanent magnet atom chip. We study ultracold atoms and produce a Bose-Einstein condensate. The magnetic trap is loaded efficiently by adiabatic transport of a magnetic trap via the application of uniform external fields. Radio frequency spectr
Excitation Spectrum of Three Dressed Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
OU-YANG Zhong-Wen; KUANG Le-Man
2000-01-01
We study quantum dynamics of three dressed Bose-Einstein condensates in a high-Q cavity. The quasiparticle excitation spectrum of this system is found numerically. The stability of the quasiparticle excitation is analyzed. It is shown that there exist instabilities in the excitation spectrum.
Are Bose-Einstein Correlations emerging from correlations of fluctuations?
Rybczynski, M.; Utyuzh, O. V.; Wilk, G.(National Centre for Nuclear Studies, Warsaw, Poland); Wlodarczyk, Z
2002-01-01
We demonstrate how Bose-Einstein correlations emerge from the correlations of fluctuations allowing for their extremely simple and fast numerical modelling. Both the advantages and limitations of this new method of implementation of BEC in the numerical modelling of high energy multiparticle processes are outlined and discussed. First applications to description of $e^+e^-$ data are given.
PHENIX results on Bose-Einstein correlation functions
,
2016-01-01
Measurement of Bose-Einstein or HBT correlations of identified charged particles provide insight into the space-time structure of particle emitting sources in heavy-ion collisions. In this paper we present the latest results from the RHIC PHENIX experiment on such measurements.
Sabari, S; Jisha, Chandroth P; Porsezian, K; Brazhnyi, Valeriy A
2015-09-01
We study the stabilization properties of dipolar Bose-Einstein condensate by temporal modulation of short-range two-body interaction. Through both analytical and numerical methods, we analyze the mean-field Gross-Pitaevskii equation with short-range two-body and long-range, nonlocal, dipolar interaction terms. We derive the equation of motion and effective potential of the dipolar condensate by variational method. We show that there is an enhancement of the condensate stability due to the inclusion of dipolar interaction in addition to the two-body contact interaction. We also show that the stability of the dipolar condensate increases in the presence of time varying two-body contact interaction; the temporal modification of the contact interaction prevents the collapse of dipolar Bose-Einstein condensate. Finally we confirm the semi-analytical prediction through the direct numerical simulations of the governing equation. PMID:26465538
Rydberg dressing of a one-dimensional Bose-Einstein condensate
Płodzień, Marcin; van Druten, N J; Kokkelmans, Servaas
2016-01-01
We study the influence of Rydberg dressed interactions in a one-dimensional (1D) Bose-Einstein Condensate (BEC). We show that 1D is advantageous over 3D for observing BEC Rydberg dressing. The effects of dressing are studied by investigating collective BEC dynamics after a rapid switch-off of the Rydberg dressing interaction. The results can be interpreted as an effective modification of the $s$-wave scattering length. We include this modification in an analytical model for the 1D BEC, and compare it to numerical calculations of Rydberg dressing under realistic experimental conditions.
Rindler-Daller, Tanja
2012-01-01
If cosmological cold dark matter (CDM) consists of light enough bosonic particles that their phase-space density exceeds unity, they will comprise a Bose-Einstein condensate (BEC). The nature of this BEC-CDM as a quantum fluid may then distinguish it dynamically from the standard form of CDM involving a collisionless gas of non-relativistic particles that interact purely gravitationally. We summarize some of the dynamical properties of BEC-CDM that may lead to observable signatures in galactic halos and present some of the bounds on particle mass and self-interaction coupling strength that result from a comparison with observed galaxies.
Numerical studies on vortices in rotating dipolar Bose-Einstein condensates
International Nuclear Information System (INIS)
We study the formation and dynamics of vortices in quasi two-dimensional dipolar Bose-Einstein condensates (BECs). We solve the time dependent two-dimensional Gross-Pitaevskii equation by using a combined split-step Crank-Nicolson (SSCN) and Fast Fourier-Transform (FFT) based numerical scheme and investigate the vortex dynamics in dipolar BECs trapped with harmonic and optical lattice potentials. The consequence of dipole-dipole interaction on vortex nucleation and number of vortices has been analysed. We observe that the breaking of symmetry due to anisotropic dipolar interaction enormously increase the speed of creation of vortices.
Anisotropic collisions of dipolar Bose-Einstein condensates in the universal regime
Burdick, Nathaniel Q; Tang, Yijun; Lev, Benjamin L
2016-01-01
We report the measurement of collisions between two Bose-Einstein condensates with strong dipolar interactions. The collision velocity is significantly larger than the internal velocity distribution widths of the individual condensates, and thus, with the condensates being sufficiently dilute, a halo corresponding to the two-body differential scattering cross section is observed. The results demonstrate a novel regime of quantum scattering, relevant to dipolar interactions, in which a large number of angular momentum states become coupled during the collision. We perform Monte-Carlo simulations to provide a detailed comparison between theoretical two-body cross sections and the experimental observations.
Schulte, T.; Drenkelforth, S.; Kruse, J.; Ertmer, W.; Arlt, J.; Sacha, K.; Zakrzewski, J.; Lewenstein, M.
2005-10-01
We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters.
International Nuclear Information System (INIS)
We investigate, both experimentally and theoretically, possible routes towards Anderson-like localization of Bose-Einstein condensates in disordered potentials. The dependence of this quantum interference effect on the nonlinear interactions and the shape of the disorder potential is investigated. Experiments with an optical lattice and a superimposed disordered potential reveal the lack of Anderson localization. A theoretical analysis shows that this absence is due to the large length scale of the disorder potential as well as its screening by the nonlinear interactions. Further analysis shows that incommensurable superlattices should allow for the observation of the crossover from the nonlinear screening regime to the Anderson localized case within realistic experimental parameters
Mixtures of ultracold gases: Fermi sea and Bose-Einstein condensate of lithium isotopes
Schreck, F.
2003-03-01
This thesis presents studies of quantum degenerate atomic gases of fermionic ^6Li and bosonic ^7Li. Degeneracy is reached by evaporative cooling of ^7Li in a strongly confining magnetic trap. Since at low temperatures direct evaporative cooling is not possible for a polarized fermionic gas, ^6Li is sympathetically cooled by thermal contact with ^7Li. In a first series of experiments both isotopes are trapped in their low-field seeking higher hyperfine states. A Fermi degeneracy of T/T_F=0.25(5) is achieved for 10^5 fermions. For more than 300 atoms, the ^7Li condensate collapses, due to the attractive interatomic interaction in this state. This limits the degeneracy reached for both species. To overcome this limit, in a second series of experiments ^7Li and ^6Li atoms are transferred to their low field seeking lower hyperfine states, where the boson-boson interaction is repulsive but weak. The inter-isotope collisions are used to thermalize the mixture. A ^7Li Bose-Einstein condensate (BEC) of 10^4 atoms immersed in a Fermi sea is produced. The BEC is quasi-one-dimensional and the thermal fraction can be negligible. The measured degeneracies are T/T_C=T/T_F=0.2(1). The temperature is measured using the bosonic thermal fraction, which vanishes at the lowest temperatures, limiting our measurement sensitivity. In a third series of experiments, the bosons are transferred into an optical trap and their internal state is changed to |F=1,m_F=1rangle, the lowest energy state. A Feshbach resonance is detected and used to produce a BEC with tunable atomic interactions. When the effective interaction between atoms is tuned to be small and attractive, we observe the formation of a matter-wave bright soliton. Propagation of the soliton without spreading over a macroscopic distance of 1.1 mm is observed. Mélanges de gaz ultrafroids: mer de Fermi et condensat de Bose-Einstein des isotopes du lithium Cette thèse décrit l'étude des gaz de fermions ^6Li et de bosons ^7Li dans le
Kornilovitch, P E; Hague, J P
2015-02-25
Both FeSe and cuprate superconductors are quasi 2D materials with high transition temperatures and local fermion pairs. Motivated by such systems, we investigate real space pairing of fermions in an anisotropic lattice model with intersite attraction, V, and strong local Coulomb repulsion, U, leading to a determination of the optimal conditions for superconductivity from Bose-Einstein condensation. Our aim is to gain insight as to why high temperature superconductors tend to be quasi 2D. We make both analytically and numerically exact solutions for two body local pairing applicable to intermediate and strong V. We find that the Bose-Einstein condensation temperature of such local pairs pairs is maximal when hopping between layers is intermediate relative to in-plane hopping, indicating that the quasi 2D nature of unconventional superconductors has an important contribution to their high transition temperatures. PMID:25629425
Dynamics of Two-Component Bose-Einstein Condensates
Baik, Eunsil
I explored the vortex dynamics in homonuclear species two-component Bose-Einstein condensates (BECs) based on the knowledge of vortex dynamics in one-component BECs. The vortex dynamics in BECs depends on the background fields induced by different external potentials and other vortices. The motion of vortices is numerically computed and the numerical results are compared to the theoretical formulas where possible. In the study of the vortex-vortex interaction dynamics in one-component BECs, a power law relationship between the motion of the vortices and their separation distance is depicted. In addition to that, the relationship between the linear and the angular velocities of the vortices is found to be similar to the relationship between the tangential and the angular velocities of classical fluid vortices. In the case of two-component BEC dynamics, two different cases are studied: one without atomic inter-conversion between the two components and the other with atomic inter-conversion. The stability analysis of the two-component BECs is conducted to identify the stable regions as well as the regions of mixed and separated states. When a vortex is seeded in one component, this vortex induces a hump in the other component at the same location as the vortex, which leads to the vortex-hump dynamics. The vortex-hump-vortex-hump interaction dynamics without atomic inter-conversion depicts a power law relation between the motion of vortex-humps and the separation distance; whereas, the vortex-hump-vortex-hump interaction dynamics with atomic inter-conversion reveals a more complex relation between the motion of vortex-humps and the separation distance.
Removal of excitations of Bose-Einstein condensates by space- and time-modulated potentials
International Nuclear Information System (INIS)
We propose that periodically in space- and time-modulated potentials (dynamic lattices) can efficiently remove the excited (the high-energy and large momentum) components of the trapped Bose-Einstein condensates (BECs) and, consequently, can result in efficient cleaning of the BECs. We prove the idea by numerically solving the mean-field models (the Schroedinger equation for noninteracting condensates and the Gross-Pitaevskii equation for interacting condensates of repulsive atoms), and we evaluate parameters and conditions for the efficient removal of excitations.
Dual-species Bose-Einstein condensate of Rb87 and Cs133
McCarron, D. J.; Cho, H. W.; Jenkin, D. L.; Köppinger, M. P.; Cornish, S. L.
2011-07-01
We report the formation of a dual-species Bose-Einstein condensate of Rb87 and Cs133 in the same trapping potential. Our method exploits the efficient sympathetic cooling of Cs133 via elastic collisions with Rb87, initially in a magnetic quadrupole trap and subsequently in a levitated optical trap. The two condensates each contain up to 2×104 atoms and exhibit a striking phase separation, revealing the mixture to be immiscible due to strong repulsive interspecies interactions. Sacrificing all the Rb87 during the cooling, we create single-species Cs133 condensates of up to 6×104 atoms.
Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding
Burton, William Cody; Chung, Woo Chang; Vadia, Samarth; Chen, Wenlan; Ketterle, Wolfgang
2016-01-01
We demonstrate a new way to extend the coherence time of separated Bose-Einstein condensates that involves immersion into a superfluid bath. When both the system and the bath have similar scattering lengths, immersion in a superfluid bath cancels out inhomogeneous potentials either imposed by external fields or inherent in density fluctuations due to atomic shot noise. This effect, which we call superfluid shielding, allows for coherence lifetimes beyond the projection noise limit. We probe the coherence between separated condensates in different sites of an optical lattice by monitoring the contrast and decay of Bloch oscillations. Our technique demonstrates a new way that interactions can improve the performance of quantum devices.
A theory of finite-temperature Bose-Einstein condensates in neutron stars
Gruber, Christine
2014-01-01
We investigate the possible occurrence of a Bose-Einstein condensed phase of matter within neutron stars due to the formation of Cooper pairs among the superfluid neutrons. To this end we study the condensation of bosonic particles under the influence of both a short-range contact and a long-range gravitational interaction in the framework of a Hartree-Fock theory. We consider a finite-temperature scenario, generalizing existing approaches, and derive macroscopic and astrophysically relevant quantities like a mass limit for neutron stars.
Critical temperature of Bose-Einstein condensation in trapped atomic Bose-Fermi mixtures
International Nuclear Information System (INIS)
We calculate the shift in the critical temperature of Bose-Einstein condensation for a dilute Bose-Fermi mixture confined by a harmonic potential, to lowest order in both the Bose-Bose and Bose-Fermi coupling constants. The relative importance of the effect on the critical temperature of the boson-boson and boson-fermion interactions is investigated as a function of the parameters of the mixture. The possible relevance of the shift of the transition temperature in current experiments on trapped Bose-Fermi mixtures is discussed. (letter to the editor)
Mackie, M; Mackie, Matt; Javanainen, Juha
2002-01-01
We theoretically examine collective two-color photoassociation of a 87Rb Bose-Einstein condensate, focusing on stimulated Raman adiabatic passage (STIRAP) from atoms to molecules. In particular, Drummond et al. [Phys. Rev. A 65, 063619 (2002); cond-mat/0110578] have predicted that particle-particle interactions limit the efficiency of atom-molecule conversion to around forty percent. We demonstrate that mean-field shifts can be sidelined by switching to modest densities, and that STIRAP subsequently proceeds at near-unit efficiency.
Critical temperature of Bose-Einstein condensation in trapped atomic Bose-Fermi mixtures
Energy Technology Data Exchange (ETDEWEB)
Albus, A P [Institut fuer Physik, Universitaet Potsdam, D-14469 Potsdam (Germany); Giorgini, S [Dipartimento di Fisica, Universita di Trento, and Istituto Nazionale per la Fisica della Materia, I-38050 Povo (Italy); Illuminati, F [Dipartimento di Fisica, Universita di Salerno, and Istituto Nazionale per la Fisica della Materia, I-84081 Baronissi (Italy); Viverit, L [Dipartimento di Fisica, Universita di Trento, and Istituto Nazionale per la Fisica della Materia, I-38050 Povo (Italy)
2002-12-14
We calculate the shift in the critical temperature of Bose-Einstein condensation for a dilute Bose-Fermi mixture confined by a harmonic potential, to lowest order in both the Bose-Bose and Bose-Fermi coupling constants. The relative importance of the effect on the critical temperature of the boson-boson and boson-fermion interactions is investigated as a function of the parameters of the mixture. The possible relevance of the shift of the transition temperature in current experiments on trapped Bose-Fermi mixtures is discussed. (letter to the editor)
Ying, Guanwen; Kouzaev, Guennadi
2016-10-01
We present the eigenmodal analysis techniques enhanced towards calculations of optical and non-interacting Bose-Einstein condensate (BEC) modes formed by random potentials and localized by Anderson effect. The results are compared with the published measurements and verified additionally by the convergence criterion. In 2-D BECs captured in circular areas, the randomness shows edge localization of the high-order Tamm-modes. To avoid strong diffusive effect, which is typical for BECs trapped by speckle potentials, a 3-D-lattice potential with increased step magnitudes is proposed, and the BECs in these lattices are simulated and plotted.
Critical temperature of Bose-Einstein condensation in trapped atomic Bose-Fermi mixtures
Albus, Alexander P.; Giorgini, Stefano; Illuminati, Fabrizio; Viverit, Luciano
2002-01-01
We calculate the shift in the critical temperature of Bose-Einstein condensation for a dilute Bose-Fermi mixture confined by a harmonic potential to lowest order in both the Bose-Bose and Bose-Fermi coupling constants. The relative importance of the effect on the critical temperature of the boson-boson and boson-fermion interactions is investigated as a function of the parameters of the mixture. The possible relevance of the shift of the transition temperature in current experiments on trappe...
Modified uncertainty principle from the free expansion of a Bose-Einstein Condensate
Castellanos, Elías
2015-01-01
We develop an analytical and numerical analysis of the free expansion of a Bose-Einstein condensate, in which we assume that the single particle energy spectrum is deformed due to a possible quantum structure of space time. Also we consider the presence of inter particle interactions in order to study more realistic and specific scenarios. The modified free velocity expansion of the condensate leads in a natural way to a modification of the uncertainty principle, which allows us to investigate some possible features of the Planck scale regime in low-energy earth-based experiments.
Tunneling Dynamics of Two-Species Molecular Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
CHEN Chang-Yong; GAO Ke-Lin
2004-01-01
We study tunneling dynamics of atomic group in two-species molecular Bose-Einstein condensates. It is shown that the tunneling of the atom group depends on not only the tunneling coupling constant between the atomic pair molecular condensate and the three-atomic group molecular condensate, but also the inter-molecular nonlinear interactions and the initial number of atoms in these condensates. It is discovered that besides oscillating tunneling current between the atomic pair molecular condensate and the three-atomic group molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained population imbalance: a macroscopic quantum self-trapping effect.
International Nuclear Information System (INIS)
We present a general method for obtaining the exact static solutions and collective excitation frequencies of a trapped Bose-Einstein condensate (BEC) with dipolar atomic interactions in the Thomas-Fermi regime. The method incorporates analytic expressions for the dipolar potential of an arbitrary polynomial density profile, thereby reducing the problem of handling nonlocal dipolar interactions to the solution of algebraic equations. We comprehensively map out the static solutions and excitation modes, including non-cylindrically-symmetric traps, and also the case of negative scattering length where dipolar interactions stabilize an otherwise unstable condensate. The dynamical stability of the excitation modes gives insight into the onset of collapse of a dipolar BEC. We find that global collapse is consistently mediated by an anisotropic quadrupolar collective mode, although there are two trapping regimes in which the BEC is stable against quadrupole fluctuations even as the ratio of the dipolar to s-wave interactions becomes infinite. Motivated by the possibility of a fragmented condensate in a dipolar Bose gas due to the partially attractive interactions, we pay special attention to the scissors modes, which can provide a signature of superfluidity, and identify a long-range restoring force which is peculiar to dipolar systems. As part of the supporting material for this paper we provide the computer program used to make the calculations, including a graphical user interface.
Roberts, D. C.; Pomeau, Y.
2005-01-01
We calculate a force due to zero-temperature quantum fluctuations on a stationary object in a moving superfluid flow. We model the object by a localized potential varying only in the flow direction and model the flow by a three-dimensional weakly interacting Bose-Einstein condensate at zero temperature. We show that this force exists for any arbitrarily small flow velocity and discuss the implications for the stability of superfluid flow.
Interferometry with Bose-Einstein Condensates in Microgravity
Müntinga, H; Krutzik, M; Wenzlawski, A; Arnold, S; Becker, D; Bongs, K; Dittus, H; Duncker, H; Gaaloul, N; Gherasim, C; Giese, E; Grzeschik, C; Hänsch, T W; Hellmig, O; Herr, W; Herrmann, S; Kajari, E; Kleinert, S; Lämmerzahl, C; Lewoczko-Adamczyk, W; Malcolm, J; Meyer, N; Nolte, R; Peters, A; Popp, M; Reichel, J; Roura, A; Rudolph, J; Schiemangk, M; Schneider, M; Seidel, S T; Sengstock, K; Tamma, V; Valenzuela, T; Vogel, A; Walser, R; Wendrich, T; Windpassinger, P; Zeller, W; van Zoest, T; Ertmer, W; Schleich, W P; Rasel, E M
2013-01-01
Atom interferometers covering macroscopic domains of space-time are a spectacular manifestation of the wave nature of matter. Due to their unique coherence properties, Bose-Einstein condensates are ideal sources for an atom interferometer in extended free fall. In this paper we report on the realization of an asymmetric Mach-Zehnder interferometer operated with a Bose-Einstein condensate in microgravity. The resulting interference pattern is similar to the one in the far-field of a double-slit and shows a linear scaling with the time the wave packets expand. We employ delta-kick cooling in order to enhance the signal and extend our atom interferometer. Our experiments demonstrate the high potential of interferometers operated with quantum gases for probing the fundamental concepts of quantum mechanics and general relativity.
Excitations of Bose-Einstein condensates at finite temperatures
Rusch, M
2000-01-01
in their frequency spectra. Where possible we derive energy shifts and lifetimes of excitations. For one particular mode, the breathing mode, the effects of the discreteness of the system are sufficiently pronounced that the simple picture of an energy shift and width fails. Experiments in spherical traps have recently become feasible and should be able to test our detailed quantitative predictions. Recent experimental observations of collective excitations of Bose condensed atomic vapours have stimulated interest in the microscopic description of the dynamics of a Bose-Einstein condensate confined in an external potential. We present a finite temperature field theory for collective excitations of trapped Bose-Einstein condensates and use a finite-temperature linear response formalism, which goes beyond the simple mean-field approximation of the Gross-Pitaevskii equation. The effect of the non-condensed thermal atoms we include using perturbation theory in a quasiparticle basis. This presents a simple scheme ...
Theory of cold atoms: Bose-Einstein statistics
Yukalov, V. I.
2016-06-01
This tutorial is the continuation of the previous tutorial part, published in (2013 Laser Phys. 23 062001), where the basic mathematical techniques required for an accurate description of cold atoms for both types of quantum statistics are expounded. In the present part, the specifics of the correct theoretical description of atoms obeying Bose-Einstein statistics are explained, including trapped Bose atoms. In the theory of systems exhibiting the phenomenon of Bose-Einstein condensation, there exists a number of delicate mathematical points, whose misunderstanding often results in principally wrong conclusions. This is why the consideration in the present tutorial is sufficiently detailed in order that the reader could clearly understand the underlying mathematics and would avoid confusions.
Bose-Einstein correlations in W-pair decays
Barate, R; Ghez, P; Goy, C; Jézéquel, S; Lees, J P; Martin, F; Merle, E; Minard, M N; Pietrzyk, B; Alemany, R; Bravo, S; Casado, M P; Chmeissani, M; Crespo, J M; Fernández, E; Fernández-Bosman, M; Garrido, L; Graugès-Pous, E; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Morawitz, P; Pacheco, A; Riu, I; Ruiz, H; Colaleo, A; Creanza, D; De Palma, M; Iaselli, Giuseppe; Maggi, G; Maggi, M; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Boix, G; Buchmüller, O L; Cattaneo, M; Cerutti, F; Ciulli, V; Davies, G; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Gianotti, F; Greening, T C; Halley, A W; Hansen, J B; Harvey, J; Janot, P; Jost, B; Kado, M; Leroy, O; Maley, P; Mato, P; Minten, Adolf G; Moutoussi, A; Ranjard, F; Rolandi, Luigi; Schlatter, W D; Schmitt, M; Schneider, O; Spagnolo, P; Tejessy, W; Teubert, F; Tournefier, E; Valassi, Andrea; Wright, A E; Ajaltouni, Ziad J; Badaud, F; Chazelle, G; Deschamps, O; Dessagne, S; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Pascolo, J M; Perret, P; Podlyski, F; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Vayaki, Anna; Blondel, A; Brient, J C; Machefert, F P; Rougé, A; Swynghedauw, M; Tanaka, R; Videau, H L; Focardi, E; Parrini, G; Zachariadou, K; Corden, M; Georgiopoulos, C H; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Chiarella, V; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Chalmers, M; Kennedy, J; Lynch, J G; Negus, P; O'Shea, V; Räven, B; Smith, D; Teixeira-Dias, P; Thompson, A S; Ward, J J; Cavanaugh, R J; Dhamotharan, S; Geweniger, C; Hanke, P; Hepp, V; Kluge, E E; Leibenguth, G; Putzer, A; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Marinelli, N; Martin, E B; Nash, J; Nowell, J; Przysiezniak, H; Sciabà, A; Sedgbeer, J K; Thompson, J C; Thomson, E; Williams, M D; Ghete, V M; Girtler, P; Kneringer, E; Kuhn, D; Rudolph, G; Bowdery, C K; Buck, P G; Ellis, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Robertson, N A; Smizanska, M; Williams, M I; Giehl, I; Hölldorfer, F; Jakobs, K; Kleinknecht, K; Kröcker, M; Müller, A S; Nürnberger, H A; Quast, G; Renk, B; Rohne, E; Sander, H G; Schmeling, S; Wachsmuth, H W; Zeitnitz, C; Ziegler, T; Aubert, Jean-Jacques; Bonissent, A; Carr, J; Coyle, P; Ealet, A; Fouchez, D; Tilquin, A; Aleppo, M; Antonelli, M; Gilardoni, S S; Ragusa, F; Büscher, V; Dietl, H; Ganis, G; Hüttmann, K; Lütjens, G; Mannert, C; Männer, W; Moser, H G; Schael, S; Settles, Ronald; Seywerd, H C J; Stenzel, H; Wiedenmann, W; Wolf, G; Azzurri, P; Boucrot, J; Callot, O; Chen, S; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Jacholkowska, A; Lefrançois, J; Serin, L; Veillet, J J; Videau, I; De Vivie de Régie, J B; Zerwas, D; Bagliesi, G; Boccali, T; Bozzi, C; Calderini, G; Dell'Orso, R; Ferrante, I; Giassi, A; Gregorio, A; Ligabue, F; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Rizzo, G; Sanguinetti, G; Sguazzoni, G; Tenchini, Roberto; Venturi, A; Verdini, P G; Blair, G A; Coles, J; Cowan, G D; Green, M G; Hutchcroft, D E; Jones, L T; Medcalf, T; Strong, J A; Botterill, David R; Clifft, R W; Edgecock, T R; Norton, P R; Tomalin, I R; Bloch-Devaux, B; Colas, P; Fabbro, B; Faïf, G; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Rosowsky, A; Seager, P; Trabelsi, A; Tuchming, B; Vallage, B; Black, S N; Dann, J H; Loomis, C; Kim, H Y; Konstantinidis, N P; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Cartwright, S L; Combley, F; Hodgson, P N; Lehto, M H; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Grupen, Claus; Hess, J; Misiejuk, A; Prange, G; Sieler, U; Borean, C; Giannini, G; Gobbo, B; Pütz, J; Rothberg, J E; Wasserbaech, S R; Williams, R W; Armstrong, S R; Elmer, P; Ferguson, D P S; Gao, Y; González, S; Hayes, O J; Hu, H; Jin, S; Kile, J; McNamara, P A; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Von Wimmersperg-Töller, J H; Wu Sau Lan; Wu, X; Zobernig, G
2000-01-01
Bose-Einstein correlations are studied in semileptonicWW --> qqbarlnu and fully hadronic WW --> qqbarqqbar W-pair decays with the ALEPH detector at LEP at centre-of-mass energies of 172, 183 and 189GeV. They are compared with those made at the Z peak after correction for the different flavour compositions. A Monte Carlo model of Bose-Einsteincorrelations based on the JETSET hadronization scheme was tuned to the Z data and reproduces the correlations in the WW --> qqbarlnu events. The same Monte Carlo reproduces the correlations in the WW --> qqbarqqbarchannel assuming independent fragmentation of the two W's. A variant thismodel with Bose-Einstein correlations between decay products of different W's is disfavoured.
Photoassociation of sodium in a Bose-Einstein condensate
International Nuclear Information System (INIS)
We form ultracold Na2 molecules by single-photon photoassociation of a Bose-Einstein condensate, measuring the photoassociation rate, linewidth, and light shift of the J=1 , v=135 vibrational level of the A1Σ+u molecular state. The photoassociation rate constant increases linearly with intensity, even where it is predicted that many-body effects might limit the rate. Our observations are in good agreement with a two-body theory having no free parameters
Vacuum quark condensate, chiral Lagrangian, and Bose-Einstein statistics
International Nuclear Information System (INIS)
In a series of articles it was recently claimed that the quantum chromodynamic (QCD) condensates are not the properties of the vacuum but of the hadrons and are confined inside them. We point out that this claim is incompatible with the chiral Lagrangian and Bose-Einstein statistics of the Goldstone bosons (pions) in chiral limit and conclude that the quark condensate must be the property of the QCD vacuum.
Dark soliton creation in Bose-Einstein condensates
Carr, L. D.; Brand, J.; Burger, S.; Sanpera, A.
2000-01-01
It is demonstrated that stable, standing dark solitons can be created in current dilute-gas Bose-Einstein condensate experiments by the proper combination of phase and density engineering. Other combinations result in a widely controllable range of grey solitons. The phonon contribution is small and is calculated precisely. The ensuing dynamics should be observable in situ, i.e. without ballistic expansion of the condensate.
Bose-Einstein Correlations from Random Walk Models
Tomasik, Boris; Pisút, J; Tomasik, Boris; Heinz, Ulrich; Pisut, Jan
1998-01-01
We argue that the recently suggested ``random walk models'' for the extrapolation of hadronic transverse mass spectra from pp or pA to AB collisions fail to describe existing data on Bose-Einstein correlations. In particular they are unable to reproduce the measured magnitude and K_\\perp-dependence of R_s in Pb+Pb collisions and the increase of R_l with increasing size of the collision system.
Geometrical pumping with a Bose-Einstein condensate
Lu, Hsin-I; Schemmer, Max; Aycock, Lauren M.; Genkina, Dina; Sugawa, Seiji; Spielman, Ian B.
2015-01-01
We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global -- topological -- properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits non-quantized charge pumping set by local -- geometrical -- properties of the band structure. Like topological charge p...
Quantum Spin Nematic States in Bose-Einstein Condensates
Zhou, Fei
2001-01-01
We review some recent results on discrete symmetries and topological order in spinor Bose-Einstein condensates (BECs) of $^{23}Na$. For spin one bosons with two-body scatterings dominated by a total spin equal to two channel, the BECs are in quantum spin nematic states at a low density limit. We study spin correlations in condensates at different limits and analyze hidde$ symmetries using a non-perturbative approach developed recently. We further more investigate the influence of hidden $Z_2$...
Rate limit for photoassociation of a Bose-Einstein condensate
Javanainen, Juha; Mackie, Matt
2001-01-01
We simulate numerically the photodissociation of molecules into noncondensate atom pairs that accompanies photoassociation of an atomic Bose-Einstein condensate into a molecular condensate. Such rogue photodissociation sets a limit on the achievable rate of photoassociation. Given the atom density \\rho and mass m, the limit is approximately 6\\hbar\\rho^{2/3}/m. At low temperatures this is a more stringent restriction than the unitary limit of scattering theory.
Qubit Residence Time Measurements with a Bose-Einstein Condensate
Sokolovski, Dmitri
2009-01-01
We show that an electrostatic qubit located near a Bose-Einstein condensate trapped in a symmetric double-well potential can be used to measure the duration the qubit has spent in one of its quantum states. The stronq, medium and weak measurement regimes are analysed and a new type of Zeno effect is discussed. The analogy between the residence and the traversal (tunnelling) times is highlighted.
Phase diffusion in a Bose-Einstein condensate of light
de Leeuw, A.W.; van der Wurff, E. C. I.; Duine, R. A.; Stoof, H.T.C.
2014-01-01
We study phase diffusion in a Bose-Einstein condensate of light in a dye-filled optical microcavity, i.e., the spreading of the probability distribution for the condensate phase. To observe this phenomenon, we propose an interference experiment between the condensed photons and an external laser. We determine the average interference patterns, considering quantum and thermal fluctuations as well as dissipative effects due to the dye. Moreover, we show that a representative outcome of individu...
Bloch oscillations of Bose-Einstein condensates: breakdown and revival.
Witthaut, D; Werder, M; Mossmann, S; Korsch, H J
2005-03-01
We investigate the dynamics of Bose-Einstein condensates in a tilted one-dimensional periodic lattice within the mean-field (Gross-Pitaevskii) description. Unlike in the linear case the Bloch oscillations decay because of nonlinear dephasing. Pronounced revival phenomena are observed. These are analyzed in detail in terms of a simple integrable model constructed by an expansion in Wannier-Stark resonance states. We also briefly discuss the pulsed output of such systems for stronger static fields.
Bose-Einstein correlations in WW pair production at LEP
Van Remortel, N
2003-01-01
This paper presents an overview of the latest results from the L3 and DELPHI collaborations concerning the measurement of Bose-Einstein correlations between identical bosons coming from different W's in fully hadronic WW decays. Using the same method, L3 sees no indication of any inter-W BEC effect, while DELPHI reports an indication of inter-W BEC between like-charged particles of the order of three standard deviations.
Bose-Einstein condensation of magnons in spin pumping systems
NAKATA, KOUKI; Korai, Yusuke
2013-01-01
We clarify the condition for the occurrence of magnon Bose-Einstein condensation (BEC) in spin pumping systems without using external pumping magnetic fields. The Goldstone model is generalized and the stability of the vacuum is closely investigated. By applying the generalized Goldstone model to spin pumping systems, the condition for the experimental realization of the stable magnon BEC in spin pumping systems is theoretically proposed.
Interference of Bose-Einstein Condensates on an Atom Chip
Shin, Y.; Sanner, C.; Jo, G. -B.; Pasquini, T. A.; Saba, M.; Ketterle, W.; Pritchard, D. E.; Vengalattore, M.; Prentiss, M.
2005-01-01
We have used a microfabricated atom chip to split a single Bose-Einstein condensate of sodium atoms into two spatially separated condensates. Dynamical splitting was achieved by deforming the trap along the tightly confining direction into a purely magnetic double-well potential. We observed the matter wave interference pattern formed upon releasing the condensates from the microtraps. The intrinsic features of the quartic potential at the merge point, such as zero trap frequency and extremel...
Simple method for collective excitation of Bose-Einstein condensate
Damski, B; Sacha, K; Zakrzewski, J; Damski, Bogdan; Karkuszewski, Zbyszek P.; Sacha, Krzysztof; Zakrzewski, Jakub
2002-01-01
An appropriate, time-dependent modification of the trapping potential may be sufficient to create effectively collective excitations in a cold atom Bose-Einstein condensate. The proposed method is complementary to earlier suggestions and should allow creating both dark solitons and vortices. It seems to be quite feasible experimentally --- it requires only a proper change in time of the potential in atomic traps, as realized in laboratories already.
Stability of trapped Bose-Einstein condensates in one-dimensional tilted optical lattice potential
Institute of Scientific and Technical Information of China (English)
Fang Jian-Shu; Liao Xiang-Ping
2011-01-01
Using the direct perturbation technique, this paper obtains a general perturbed solution of the Bose-Einstein condensates trapped in one-dimensional tilted optical lattice potential. We also gave out two necessary and sufficient conditions for boundedness of the perturbed solution. Theoretical analytical results and the corresponding numerical results show that the perturbed solution of the Bose-Einstein condensate system is unbounded in general and indicate that the Bose-Einstein condensates are Lyapunov-unstable. However, when the conditions for boundedness of the perturbed solution are satisfied, then the Bose-Einstein condensates are Lyapunov-stable.
Bose-Einstein condensation of atoms and photons
International Nuclear Information System (INIS)
Bose-Einstein condensation has now been observed in diverse physical systems, starting from liquid Helium, excitons, to alkali atoms at nanokelvin temperature. The trapped cold atoms have provided an ideal venue for exploring fascinating ideas, ranging from Kosterlitz- Thouless (KT) phase transition, metal-insulator quantum phase transition to the realization of Abelian and non- Abelian gauge fields and solitonic excitations, in a controlled environment. Here, after a brief introduction to condensation phenomena in free space and trap, we explicate the working of the magneto optical trap, the work horse of the cold-atom laboratories. Subsequently, we illustrate the properties of experimentally realized dark, bright and grey solitons in the cigar shaped Bose-Einstein condensate (BEC). Focusing on a pan-cake type BEC in two dimensions, the basic aspects of the unique vortex excitations on a plane is elaborated, from which the Kosterlitz-Thouless phase transition follows, when the bound vortex-anti-vortex pairs unbind at TKT. We then describe the recent realization of Bose-Einstein condensation of the ubiquitous photons at room temperature. (author)
Probing a scattering resonance in Rydberg molecules with a Bose-Einstein condensate
Schlagmüller, Michael; Nguyen, Huan; Lochead, Graham; Engel, Felix; Böttcher, Fabian; Westphal, Karl M; Kleinbach, Kathrin S; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Pérez-Ríos, Jesús; Greene, Chris H
2015-01-01
We present spectroscopy of a single Rydberg atom excited within a Bose-Einstein condensate. We not only observe the density shift as discovered by Amaldi and Segre in 1934, but a line shape which changes with the principal quantum number n. The line broadening depends precisely on the interaction potential energy curves of the Rydberg electron with the neutral atom perturbers. In particular, we show the relevance of the triplet p-wave shape resonance in the Rydberg electron-Rb(5S) scattering, which significantly modifies the interaction potential. With a peak density of 5.5x10^14 cm^-3, and therefore an inter-particle spacing of 1300 a0 within a Bose-Einstein condensate, the potential energy curves can be probed at these Rydberg ion - neutral atom separations. We present a simple microscopic model for the spectroscopic line shape by treating the atoms overlapped with the Rydberg orbit as zero-velocity, uncorrelated, point-like particles, with binding energies associated with their ion-neutral separation, and ...
Tacla, Alexandre B.; Caves, Carlton M.
2013-02-01
We study the mean-field dynamics and the reduced-dimension character of two-mode Bose-Einstein condensates (BECs) in highly anisotropic traps. By means of perturbative techniques, we show that the tightly confined (transverse) degrees of freedom can be decoupled from the dynamical equations at the expense of introducing additional effective three-body, attractive, intra- and inter-mode interactions into the dynamics of the loosely confined (longitudinal) degrees of freedom. These effective interactions are mediated by changes in the transverse wave function. The perturbation theory is valid as long as the nonlinear scattering energy is small compared to the transverse energy scales. This approach leads to reduced-dimension mean-field equations that optimally describe the evolution of a two-mode condensate in general quasi-one-dimensional (1D) and quasi-two-dimensional geometries. We use this model to investigate the relative phase and density dynamics of a two-mode, cigar-shaped 87Rb BEC. We study the relative-phase dynamics in the context of a nonlinear Ramsey interferometry scheme, which has recently been proposed as a novel platform for high-precision interferometry. Numerical integration of the coupled, time-dependent, three-dimensional, two-mode Gross-Pitaevskii equations for various atom numbers shows that this model gives a considerably more refined analytical account of the mean-field evolution than an idealized quasi-1D description.
Wang, Deng-Shan; Han, Wei; Shi, Yuren; Li, Zaidong; Liu, Wu-Ming
2016-07-01
The spin-1 Bose-Einstein condensates trapped in a standing light wave can be described by three coupled Gross-Pitaevskii equations with a periodic potential. In this paper, nine families of stationary solutions without phase structures in the form of Jacobi elliptic functions are proposed, and their stabilities are analyzed by both linear stability analysis and dynamical evolutions. Taking the ferromagnetic 87Rb atoms and antiferromagnetic (polar) 23Na atoms as examples, we investigate the stability regions of the nine stationary solutions, which are given in term of elliptic modulus k. It is shown that for the same stationary solution the stability regions of condensates with antiferromagnetic (polar) spin-dependent interactions are larger than that of the condensates with ferromagnetic ones. The dn-dn-dn stationary solution is the most stable solution among the nine families of stationary solutions. Moreover, in the same standing light wave, the spin-1 Bose-Einstein condensates are more stable than the scalar Bose-Einstein condensate.
Quench dynamics of a Bose-Einstein condensate under synthetic spin-orbit coupling
Deng, Tian-Shu; Zhang, Wei; Yi, Wei; Guo, Guang-Can
2016-05-01
We study the quench dynamics of a Bose-Einstein condensate under a Raman-assisted synthetic spin-orbit coupling. To model the dynamical process, we adopt a self-consistent Bogoliubov approach, which is equivalent to applying the time-dependent Bogoliubov-de Gennes equations. We investigate the dynamics of the condensate fraction as well as the momentum distribution of the Bose gas following a sudden change of system parameters. Typically, the system evolves into a steady state in the long-time limit, which features an oscillating momentum distribution and a stationary condensate fraction. We investigate how different quench parameters such as the inter- and intraspecies interactions and the spin-orbit-coupling parameters affect the condensate fraction in the steady state. Furthermore, we find that the time average of the oscillatory momentum distribution in the long-time limit can be described by a generalized Gibbs ensemble with two branches of momentum-dependent Gibbs temperatures. Our study is relevant to the experimental investigation of dynamical processes in a spin-orbit-coupled Bose-Einstein condensate.
Cosmological evolution of a complex scalar field with repulsive or attractive self-interaction
Suárez, Abril
2016-01-01
We study the cosmological evolution of a complex scalar field with a self-interaction potential $V(|\\varphi|^2)$, possibly describing self-gravitating Bose-Einstein condensates, using a fully general relativistic treatment. We generalize the hydrodynamic representation of the Klein-Gordon-Einstein equations in the weak field approximation developed in our previous paper. We establish the general equations governing the evolution of a spatially homogeneous complex scalar field in an expanding background. We show how they can be simplified in the fast oscillation regime and derive the equation of state of the scalar field in parametric form for an arbitrary potential. We explicitly consider the case of a quartic potential with repulsive or attractive self-interaction and determine the phase diagram of the scalar field. We show that the transition between the weakly self-interacting regime and the strongly self-interacting regime depends on how the scattering length of the bosons compares with their effective Sc...
Engineered potentials in ultracold Bose-Einstein condensates
Campbell, Daniel L.
Bose-Einstein condensates (BECs) are a recent addition to the portfolio of quantum materials some of which have profound commercial and military applications e.g., superconductors, superfluids and light emitting diodes. BECs exist in the lowest motional modes of a trap and have the lowest temperatures achieved by mankind. With full control over the shape of the trap the experimentalist may explore an extremely diverse set of Hamiltonians which may be altered mid-experiment. These properties are particularly suited for realizing novel quantum systems. This thesis explores interaction-driven domain formation and the subsequent domain coarsening for two immiscible BEC components. Because quantum coherences associated with interactions in BECs can be derived from low energy scattering theory we compare our experimental results to both a careful simulation (performed by Brandon Anderson) and an analytical prediction. This result very carefully explores the question of how a metastable system relaxes at the extreme limit of low temperature. We also explore spin-orbit coupling (SOC) of a BEC which links the linear and discrete momentum transferable by two counterpropagating ''Raman'' lasers that resonantly couple the ground electronic states of our BECs. SOC is used similarly in condensed matter systems to describe coupling between charge carrier spin and crystal momentum and is a necessary component of the quantum spin Hall effect and topological insulators. SOC links the linear and discrete momentum transferable by two counterpropagating ''Raman'' lasers and a subset of the ground electronic states of our BEC. The phases of an effective 2-spin component spin-orbit coupling (SOC) in a spin-1 BEC are described in Lin et al. (2011). We measure the phase transition between two phases of a spin-1 BEC with SOC which cannot be mimicked by a spin-1/2 system. The order parameter that describes transitions between these two phases is insensitive to magnetic field fluctuations. I
Bose-Einstein-condensate interferometer with macroscopic arm separation
Garcia-Salazar, Ofir
The basis of our study was to implement an atom interferometer using 87Rb Bose Einstein condensates which has advantages in sensitivity over current interferometers that use cold atoms and light. Interferometers are devices which can accurately measure phase differences between waves that interfere and originate from a coherent source (or sources). We developed a weakly confining waveguide having o x ≈ 3 Hz, oz ≈ 3 Hz, o y ≈ 1 Hz as characteristic oscillation frequencies. Weak confinement, specially along the "y" direction, means the condensate can displace along this axis and interaction energies of the atoms in the condensate are reduced [43]. We have been able to successfully demonstrate condensate interference in our waveguide using a Mach Zehnder configuration. Coherence times of up to 40 ms have been observed, and the maximum center to center separation of the condensates recorded was of 240 mum. At this separation length, the two clouds corresponding to each of the interferometer's arms are completely separated. To our knowledge, this is the first time a picture has been taken of two groups of atoms separated by a macroscopic distance while in a quantum superposition of being in either cloud. The coherence time and length measurements presented in our work have been among the longest ones achieved so far for interferometry using condensed atoms. Interference visibility of 60% was observed up to 40 ms. We believe technical limitations in the techniques used to manipulate the atoms are responsible for the sudden drop in visibility at 44 ms. For example, unwanted laser reflections and interference patterns in our chamber affect the techniques used to split and reflect the atoms. However, we see coherence up to 80 ms from shot to shot, suggesting we could dramatically improve coherence times. Because of the weak confinement of our trap, we expect to improve coherence times up to an order of magnitude before running into phase diffusion effects [27]. It is
Measurement of Genuine Three-Particle Bose-Einstein Correlations in Hadronic Z decay
Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M
2002-01-01
We measure three-particle Bose-Einstein correlations in hadronic Z decay with the L3 detector at LEP. Genuine three-particle Bose-Einstein correlations are observed. By comparing two- and three-particle correlations we find that the data are consistent with fully incoherent pion production.
Characterisation of the dynamical quantum state of a zero temperature Bose-Einstein condensate
Rogel-Salazar, J.; Choi, S.; New, G. H. C.; Burnett, K.
2003-01-01
We describe the quantum state of a Bose-Einstein condensate at zero temperature. By evaluating the Q-function we show that the ground state of Bose-Einstein condensate under the Hartree approximation is squeezed. We find that multimode Schroedinger cat states are generated as the condensate evolves in a ballistic expansion.
Coherence and Squeezing of Bose-Einstein Condensates in Double Wells
Yi, Xiao-jie
2016-05-01
We investigate coherence and squeezing of a two-mode Bose-Einstein condensate trapped in a double-well potential. By analytically deriving the form of coherence and numerically calculating the squeezing parameter, we show that the coherence and the squeezing may be controlled by adjusting some parameters of the two-mode Bose-Einstein condensate.
Dynamical spin-density waves in a spin-orbit-coupled Bose-Einstein condensate
Li, Yan; Qu, Chunlei; Zhang, Yongsheng; Zhang, Chuanwei
2015-07-01
Synthetic spin-orbit (SO) coupling, an important ingredient for quantum simulation of many exotic condensed matter physics, has recently attracted considerable attention. The static and dynamic properties of a SO-coupled Bose-Einstein condensate (BEC) have been extensively studied in both theory and experiment. Here we numerically investigate the generation and propagation of a dynamical spin-density wave (SDW) in a SO-coupled BEC using a fast moving Gaussian-shaped barrier. We find that the SDW wavelength is sensitive to the barrier's velocity while varies slightly with the barrier's peak potential or width. We qualitatively explain the generation of SDW by considering a rectangular barrier in a one-dimensional system. Our results may motivate future experimental and theoretical investigations of rich dynamics in the SO-coupled BEC induced by a moving barrier.
Renormalization group analysis of ultracold Fermi gases with two-body attractive interaction
Guo, Xiaoyong; Chi, Zimeng; Zheng, Qiang; Wang, Zaijun
2016-01-01
We propose a new functional renormalization group (RG) strategy to investigate the many-body physics of interacting ultracold Fermi gases. By mapping the Ginzburg-Landau (GL) action of Fermi gases onto a complex φ4-model, we can obtain the closed flow equation in the one-loop approximation. An analysis of the emerging RG flow gives the ground state behavior. The Hamiltonian of a Fermi gas with a two-body attractive interaction is used as a demonstration to clarify our treatment. The fixed point structure reveals not only the condensation phase transition, but also the Bardeen-Cooper-Schrieffer (BCS) to Bose-Einstein condensation (BEC) crossover. The effect of the imaginary time renormalization is also discussed. It is shown that for the dynamical field configuration our RG procedure can reproduce the well known theoretical results of BCS-BEC crossover, while under a static approximation the phase transition takes place at a higher critical temperature.
Bose-Einstein condensation in antiferromagnets at low temperatures
International Nuclear Information System (INIS)
The Bose-Einstein condensation (BEC) was predicted by Einstein in 1925 and this effect is characterized by the formation of a collective quantum state, when macroscopic number of particles is governed by a single wave function. The BEC of magnons was discovered experimentally in superfluid phase of 3He. In the present work we report our progress on the BEC of magnons investigations in solid antiferromagnets at low temperatures by magnetic resonance methods. The duration of the FID signal in two samples of easy-plane antiferromagnets CsMnF3 has been studied. Obtained data confirm the formation of magnon BEC in antiferromagnet CsMnF3
Composite nature of hadrons and Bose-Einstein correlations
Bialas, A.
2016-07-01
I am reporting results of two papers, written together with W.Florkowski and K.Zalewski [1, 2], discussing the consequences of the observation [3] that, due to their composite nature and thus finite size, hadrons observed in the HBT measurements must be correlated in space-time. Using the blast-wave model [4] adjusted [1] to ALICE data on the measured HBT radii in pp collisions at 7 TeV [5], the full Bose-Einstein correlation functions in three direction (out, side, long) are evaluated. The results are presented together with some additional comments.
Vortices and ring solitons in Bose-Einstein condensates
International Nuclear Information System (INIS)
The form and stability properties of axisymmetric and spherically symmetric stationary states in two and three dimensions, respectively, are elucidated for Bose-Einstein condensates. These states include the ground state, central vortices, and radial excitations of both. The latter are called ring solitons in two dimensions and spherical shells in three. The nonlinear Schroedinger equation is taken as the fundamental model; both extended and harmonically trapped condensates are considered. It is found that the instability times of ring solitons can be long compared to experimental time scales, making them effectively stable over the lifetime of an experiment
Bose-Einstein condensation in the early universe
Energy Technology Data Exchange (ETDEWEB)
Morikawa, M. [Department of Physics, Ochanomizu University, Bunkyo, Tokyo (Japan)
2010-04-15
By introducing the Bose-Einstein condensation dynamics (BEC), we develop a unified model of dark energy and dark matter. The two phases of BEC (=dark energy) and normal gas (=dark matter) transform with each other through the phase transition. We study the present mild acceleration, the inflation in the early universe, and the reduction of the cosmological constant. We find the stagflation regime when the cosmic expansion stops and the uniform mode of BEC becomes unstable. We also comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present. (Abstract Copyright [2010], Wiley Periodicals, Inc.)
Bose-Einstein condensation of alkaline earth atoms: $^{40}${Ca}
Kraft, Sebastian; Vogt, Felix; Appel, Oliver; Riehle, Fritz; Sterr, Uwe
2009-01-01
We have achieved Bose-Einstein condensation of $^{40}$Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground state s-wave scattering length of $^{40}$Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about $2 \\cdot 10^4$ atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less ...
Tunneling of Spinor Bose-Einstein Condensates in Optical Lattice
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
In this letter, we have studied the tunneling effects and fluctuations of spinor Bose-Einstein condensates in optical lattice. It is found that there exist tunneling effects and fluctuations between lattices l and l + 1, l and l - 1,respectively. In particular, when the optical lattice is infinitely long and the spin excitations are in the long-wavelength limit, tunneling effects disappear between lattices l and l+ 1, and l and l - 1. In this case the fluctuations are a constant,and the magnetic soliton appears.
Propagation of Sound in a Bose-Einstein Condensate
Energy Technology Data Exchange (ETDEWEB)
Andrews, M.R.; Kurn, D.M.; Miesner, H.; Durfee, D.S.; Townsend, C.G.; Inouye, S.; Ketterle, W. [Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
1997-07-01
Sound propagation has been studied in a magnetically trapped dilute Bose-Einstein condensate. Localized excitations were induced by suddenly modifying the trapping potential using the optical dipole force of a focused laser beam. The resulting propagation of sound was observed using a novel technique, rapid sequencing of nondestructive phase-contrast images. The speed of sound was determined as a function of density and found to be consistent with Bogoliubov theory. This method may generally be used to observe high-lying modes and perhaps second sound. {copyright} {ital 1997} {ital The American Physical Society}
Geometrical Pumping with a Bose-Einstein Condensate
Lu, H.-I.; Schemmer, M.; Aycock, L. M.; Genkina, D.; Sugawa, S.; Spielman, I. B.
2016-05-01
We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global—topological—properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local—geometrical—properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet's position in each unit cell, i.e., the polarization.
Bose-Einstein Condensation of Photons and Photon Pairs
Institute of Scientific and Technical Information of China (English)
张建军; 袁建辉; 张俊佩; 成泽
2012-01-01
We investigate the Bose-Einstein condensation of photons and photon pairs in a two-dimension optical microcavity. We find that in the paraxial approximation, the mixed gas of photons and photon pairs is formally equivalent to a two dimension system of massive bosons with non-vanishing chemical potential, which implies the existence of two possible condensate phase. We also discuss the quantum phase transition of the system and obtain the critical point analytically. Moreover, we find that the quantum phase transition of the system can be interpreted as second harmonic generation.
Cooling of a Bose-Einstein Condensate by Spin Distillation.
Naylor, B; Maréchal, E; Huckans, J; Gorceix, O; Pedri, P; Vernac, L; Laburthe-Tolra, B
2015-12-11
We propose and experimentally demonstrate a new cooling mechanism leading to purification of a Bose-Einstein condensate (BEC). Our scheme starts with a BEC polarized in the lowest energy spin state. Spin excited states are thermally populated by lowering the single particle energy gap set by the magnetic field. Then, these spin-excited thermal components are filtered out, which leads to an increase of the BEC fraction. We experimentally demonstrate such cooling for a spin 3 ^{52}Cr dipolar BEC. Our scheme should be applicable to Na or Rb, with the perspective to reach temperatures below 1 nK. PMID:26705630
Observation of solitonic vortices in Bose-Einstein condensates.
Donadello, Simone; Serafini, Simone; Tylutki, Marek; Pitaevskii, Lev P; Dalfovo, Franco; Lamporesi, Giacomo; Ferrari, Gabriele
2014-08-01
We observe solitonic vortices in an atomic Bose-Einstein condensate (BEC) after free expansion. Clear signatures of the nature of such defects are the twisted planar density depletion around the vortex line, observed in absorption images, and the double dislocation in the interference pattern obtained through homodyne techniques. Both methods allow us to determine the sign of the quantized circulation. Experimental observations agree with numerical simulations. These solitonic vortices are the decay product of phase defects of the BEC order parameter spontaneously created after a rapid quench across the BEC transition in a cigar-shaped harmonic trap and are shown to have a very long lifetime. PMID:25148333
Spinor condensates and light scattering from Bose-Einstein condensates
International Nuclear Information System (INIS)
These notes discuss-two aspects of the physics of atomic Bose-Einstein condensates: optical properties and spinor condensates. The first topic includes light scattering experiments which probe the excitations of a condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor condensates and describe studies of ground-state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling. (authors)
Space-Time Curvature Signatures in Bose-Einstein Condensates
Matos, Tonatiuh
2015-01-01
We derive a generalized Gross-Pitaevski (GP) equation immersed on a electromagnetic and a weak gravitational field starting from the covariant Complex Klein-Gordon field in a curved space-time. We compare it with the GP equation where the gravitational field is added by hand as an external potential. We show that there is a small difference of order $g z/c^2$ between them that could be measured in the future using Bose-Einstein Condensates (BEC). This represents the next order correction to the Newtonian gravity in a curved space-time.
Vortex formation during the growth of Bose-Einstein condensates
Weiler, Chad; Neely, Tyler; Scherer, David; Anderson, Brian
2007-06-01
We experimentally study of the growth of Bose-Einstein condensates in harmonic trapping potentials with laser-induced perturbations to the potential well. We find that some time- independent perturbations can significantly impact the growth process and final state of the BEC. In particular, in numerical simulations and our experiments, we have observed the generation of vortices and vortex-antivortex pairs as a result of creating BECs in perturbed potentials. We will describe the results of our ongoing and completed experiments (D.R. Scherer, C.N. Weiler, T.W. Neely, B.P. Anderson, cond-mat/0610187, to be published in Phys. Rev. Lett.).
Bose-Einstein Correlations and the Tau-Model
Metzger, W J; Csörgő, T; Kittel, W
2011-01-01
Bose-Einstein correlations of pairs of identical charged pions produced in hadronic Z decays are analyzed in terms of various parametrizations. A good description is achieved using a L\\'evy stable distribution in conjunction with a model where a particle's momentum is highly correlated with its space-time point of production, the tau model. However, a small but significant elongation of the particle emission region is observed in the Longitudinal Center of Mass frame, which is not accommodated in the tau model. This is investigated using an ad hoc modification of the tau model.
Pumping of twin-trap Bose-Einstein condensates
Steel, M. J.; Walls, D. F.
1997-01-01
We consider extensions of the twin-trap Bose-Einstein condensate system of Javaneinen and Yoo [Phys. Rev. Lett., 76, 161--164 (1996)] to include pumping and output couplers. Such a system permits a continual outflow of two beams of atoms with a relative phase coherence maintained by the detection process. We study this system for two forms of thermal pumping, both with and without the influence of inter-atomic collisions. We also examine the effects of pumping on the phenomenon of collapses a...
Geometrical Pumping with a Bose-Einstein Condensate.
Lu, H-I; Schemmer, M; Aycock, L M; Genkina, D; Sugawa, S; Spielman, I B
2016-05-20
We realized a quantum geometric "charge" pump for a Bose-Einstein condensate (BEC) in the lowest Bloch band of a novel bipartite magnetic lattice. Topological charge pumps in filled bands yield quantized pumping set by the global-topological-properties of the bands. In contrast, our geometric charge pump for a BEC occupying just a single crystal momentum state exhibits nonquantized charge pumping set by local-geometrical-properties of the band structure. Like topological charge pumps, for each pump cycle we observed an overall displacement (here, not quantized) and a temporal modulation of the atomic wave packet's position in each unit cell, i.e., the polarization.
Fano resonances control and slow light with Bose-Einstein Condensate in a cavity setup
Akram, M Javed; Khan, M Miskeen; Saif, Farhan
2015-01-01
We theoretically investigate the probe field transmission in an optomechanical cavity setup with Bose-Einstein Condensate (BEC), where the standing wave that forms in the cavity results in an one-dimensional optical lattice potential. We report that in the presence of atom-atom interactions, the coupling of the cavity field with condensate (Bogoliubov mode), the cavity field fluctuations and the condensate fluctuations leads to the emergence of the tunable Fano resonances in the probe absorption spectrum. Within the experimental reach, based on analytical and numerical simulations, we find that the optomechanical system with BEC provides great flexibility to tune the Fano resonances, as the width of the resonance is controllable by the coupling field and additionally, with the atom-atom interaction. Moreover, Fano resonances are analyzed for the fluctuations of the cavity field and the fluctuations of the condensate with finite atomic two-body interaction, which shows an excellent compatibility with the origi...
Multiple dark-bright solitons in atomic Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
Yan, D.; Kevrekidis, P. G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003-4515 (United States); Chang, J. J.; Hamner, C.; Engels, P. [Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164 (United States); Achilleos, V.; Frantzeskakis, D. J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, GR-157 84 Athens (Greece); Carretero-Gonzalez, R. [Nonlinear Dynamical Systems Group, Department of Mathematics and Statistics and Computational Science Research Center, San Diego State University, San Diego, California 92182-7720 (United States); Schmelcher, P. [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, D-22761 Hamburg (Germany)
2011-11-15
Motivated by recent experimental results, we present a systematic theoretical analysis of dark-bright-soliton interactions and multiple-dark-bright-soliton complexes in atomic two-component Bose-Einstein condensates. We study analytically the interactions between two dark-bright solitons in a homogeneous condensate and then extend our considerations to the presence of the trap. We illustrate the existence of robust stationary dark-bright-soliton ''molecules,'' composed of two or more solitons, which are formed due to the competition of the interaction forces between the dark- and bright-soliton components and the trap force. Our analysis is based on an effective equation of motion, derived for the distance between two dark-bright solitons. This equation provides equilibrium positions and characteristic oscillation frequencies of the solitons, which are found to be in good agreement with the eigenfrequencies of the anomalous modes of the system.
Phase-Imprinting of Bose-Einstein Condensates with Rydberg Impurities.
Mukherjee, Rick; Ates, Cenap; Li, Weibin; Wüster, Sebastian
2015-07-24
We show how the phase profile of Bose-Einstein condensates can be engineered through its interaction with localized Rydberg excitations. The interaction is made controllable and long range by off-resonantly coupling the condensate to another Rydberg state with laser light. Our technique allows the mapping of entanglement generated in systems of few strongly interacting Rydberg atoms onto much larger atom clouds in hybrid setups. As an example we discuss the creation of a spatial mesoscopic superposition state from a bright soliton. Additionally, the phase imprinted onto the condensate using the Rydberg excitations is a diagnostic tool for the latter. For example, a condensate time-of-flight image would permit reconstructing the pattern of an embedded Rydberg crystal. PMID:26252669
A geometrothermodynamic approach to ideal quantum gases and Bose-Einstein condensates
Quevedo, Hernando
2015-01-01
We analyze in the context of geometrothermodynamics the behavior of ideal quantum gases which satisfy either the Fermi statistics or the Bose statistics. Although the corresponding Hamiltonian does not contain a potential, indicating the lack of classical thermodynamic interaction, we show that the curvature of the equilibrium space is non-zero, and can be interpreted as a measure of the effective quantum interaction between the gas particles. In the limiting case of a classical Boltzmann gas, we show that the equilibrium space becomes flat, as expected from the physical viewpoint. In addition, we derive a thermodynamic fundamental equation for the Bose-Einstein condensation and, using the Ehrenfest scheme, we show that it can be considered as a first order phase transition which in the equilibrium space corresponds to a curvature singularity. This result indicates that the curvature of the equilibrium space can be used to measure the thermodynamic interaction in classical and quantum systems.
Coherent magnon optics in a ferromagnetic spinor Bose-Einstein condensate.
Marti, G Edward; MacRae, Andrew; Olf, Ryan; Lourette, Sean; Fang, Fang; Stamper-Kurn, Dan M
2014-10-10
We measure the dispersion relation, gap, and magnetic moment of a magnon in the ferromagnetic F = 1 spinor Bose-Einstein condensate of (87)Rb. From the dispersion relation we measure an average effective mass 1.033(2)(stat)(10)(sys) times the atomic mass, as determined by interfering standing and running coherent magnon waves within the dense and trapped condensed gas. The measured mass is higher than theoretical predictions of mean-field and beyond-mean-field Beliaev theory for a bulk spinor Bose gas with s-wave contact interactions. We observe a magnon energy gap of h × 2.5(1)(stat)(2)(sys) Hz, which is consistent with the predicted effect of magnetic dipole-dipole interactions. These dipolar interactions may also account for the high magnon mass. The effective magnetic moment of -1.04(2)(stat)(8)(sys) times the atomic magnetic moment is consistent with mean-field theory. PMID:25375719
Collisional Dynamics of Half-Quantum Vortices in a Spinor Bose-Einstein Condensate
Seo, Sang Won; Kwon, Woo Jin; Kang, Seji; Shin, Y.
2016-05-01
We present an experimental study on the interaction and dynamics of half-quantum vortices (HQVs) in an antiferromagnetic spinor Bose-Einstein condensate. By exploiting the orbit motion of a vortex dipole in a trapped condensate, we perform a collision experiment of two HQV pairs, and observe that the scattering motions of the HQVs is consistent with the short-range vortex interaction that arises from nonsingular magnetized vortex cores. We also investigate the relaxation dynamics of turbulent condensates containing many HQVs, and demonstrate that spin wave excitations are generated by the collisional motions of the HQVs. The short-range vortex interaction and the HQV-magnon coupling represent two characteristics of the HQV dynamics in the spinor superfluid.
Collisional Dynamics of Half-Quantum Vortices in a Spinor Bose-Einstein Condensate.
Seo, Sang Won; Kwon, Woo Jin; Kang, Seji; Shin, Y
2016-05-01
We present an experimental study on the interaction and dynamics of half-quantum vortices (HQVs) in an antiferromagnetic spinor Bose-Einstein condensate. By exploiting the orbit motion of a vortex dipole in a trapped condensate, we perform a collision experiment of two HQV pairs, and observe that the scattering motions of the HQVs is consistent with the short-range vortex interaction that arises from nonsingular magnetized vortex cores. We also investigate the relaxation dynamics of turbulent condensates containing many HQVs, and demonstrate that spin wave excitations are generated by the collisional motions of the HQVs. The short-range vortex interaction and the HQV-magnon coupling represent two characteristics of the HQV dynamics in the spinor superfluid.
Excitation spectra of a Bose-Einstein condensate with an angular spin-orbit coupling
Vasić, Ivana; Balaž, Antun
2016-09-01
A theoretical model of a Bose-Einstein condensate with angular spin-orbit coupling has recently been proposed and it has been established that a half-skyrmion represents the ground state in a certain regime of spin-orbit coupling and interaction. Here we investigate low-lying excitations of this phase by using the Bogoliubov method and numerical simulations of the time-dependent Gross-Pitaevskii equation. We find that a sudden shift of the trap bottom results in a complex two-dimensional motion of the system's center of mass that is markedly different from the response of a competing phase, and comprises two dominant frequencies. Moreover, the breathing mode frequency of the half-skyrmion is set by both the spin-orbit coupling and the interaction strength, while in the competing state it takes a universal value. Effects of interactions are especially pronounced at the transition between the two phases.
Institute of Scientific and Technical Information of China (English)
Li Hong; Wang Dong-Ning
2009-01-01
The dynamics of a dark soliton has been investigated in a Bose-Einstein condensate with an external magnetic trap, and the effects of localized impurity on the dynamics are discussed by the variational approach based on the renormalized integrals of motion. The reciprocal movement of the dark soliton is discussed by performing a standard linear analysis, and it is found that the effects of the localized impurity depend strictly on the positive or negative value of the impurity strength corresponding to the repulsive or attractive impurity. The numerical results confirm the theoretical analysis, and show that the effects also depend on the effective nonlinear coefficient and the harmonic frequency.
Collapsing dynamics of attractive Bose-Einstein condensates
DEFF Research Database (Denmark)
Bergé, L.; Juul Rasmussen, J.
2002-01-01
The self-similar collapse of 3D and quasi-2D atom condensates with negative scattering length is examined. 3D condensates are shown to blow up following the scenario of weak collapse, for which 3-body recombination weakly dissipates the atoms. In contrast, 2D condensates undergo a strong collapse...
Bose-Einstein condensation on a manifold with non-negative Ricci curvature
International Nuclear Information System (INIS)
The Bose-Einstein condensation for an ideal Bose gas and for a dilute weakly interacting Bose gas in a manifold with non-negative Ricci curvature is investigated using the heat kernel and eigenvalue estimates of the Laplace operator. The main focus is on the nonrelativistic gas. However, special relativistic ideal gas is also discussed. The thermodynamic limit of the heat kernel and eigenvalue estimates is taken and the results are used to derive bounds for the depletion coefficient. In the case of a weakly interacting gas, Bogoliubov approximation is employed. The ground state is analyzed using heat kernel methods and finite size effects on the ground state energy are proposed. The justification of the c-number substitution on a manifold is given
Phase Separation and Dynamics of two-component Bose-Einstein condensates
Lee, Kean Loon; Liu, I-Kang; Wacker, Lars; Arlt, Jan J; Proukakis, Nick P
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 between mixed and separated phases is fully characterised by a `miscibility parameter', based on the ratio of intra- to inter-species interaction strengths. Here we show, however, that this parameter is no longer the optimal one for trapped gases, for which the location of the phase boundary depends critically on atom numbers. We demonstrate how monitoring of damping rates and frequencies of dipole oscillations enables the experimental mapping of the phase diagram by numerical implementation of a fully self-consistent finite-temperature kinetic theory for binary condensates. The change in damping rate is explained in terms of surface oscillation in the immiscible regime, and counterflow instability in the miscible reg...
Quasiparticle Properties of a Mobile Impurity in a Bose-Einstein Condensate.
Christensen, Rasmus Søgaard; Levinsen, Jesper; Bruun, Georg M
2015-10-16
We develop a systematic perturbation theory for the quasiparticle properties of a single impurity immersed in a Bose-Einstein condensate. Analytical results are derived for the impurity energy, effective mass, and residue to third order in the impurity-boson scattering length. The energy is shown to depend logarithmically on the scattering length to third order, whereas the residue and the effective mass are given by analytical power series. When the boson-boson scattering length equals the boson-impurity scattering length, the energy has the same structure as that of a weakly interacting Bose gas, including terms of the Lee-Huang-Yang and fourth order logarithmic form. Our results, which cannot be obtained within the canonical Fröhlich model of an impurity interacting with phonons, provide valuable benchmarks for many-body theories and for experiments. PMID:26550852
Bai, Xiao-Dong; Zhang, Mei; Xiong, Jun; Yang, Guo-Jian; Deng, Fu-Guo
2015-01-01
We investigate the formation of discrete breathers (DBs) and the dynamics of the mixture of two-species Bose-Einstein condensates (BECs) in open boundary optical lattices using the discrete nonlinear Schrödinger equations. The results show that the coupling of intra- and interspecies interaction can lead to the existence of pure single-species DBs and symbiotic DBs (i.e., two-species DBs). Furthermore, we find that there is a selective distillation phenomenon in the dynamics of the mixture of two-species BECs. One can selectively distil one species from the mixture of two-species BECs and can even control dominant species fraction by adjusting the intra- and interspecies interaction in optical lattices. Our selective distillation mechanism may find potential application in quantum information storage and quantum information processing based on multi-species atoms. PMID:26597592
Semi-classical dynamics of superradiant Rayleigh scattering in a Bose-Einstein condensate
Müller, J. H.; Witthaut, D.; le Targat, R.; Arlt, J. J.; Polzik, E. S.; Hilliard, A. J.
2016-10-01
Due to its coherence properties and high optical depth, a Bose-Einstein condensate [BEC] provides an ideal setting to investigate collective atom-light interactions. Superradiant light scattering [SLS] in a BEC is a fascinating example of such an interaction. It is an analogous process to Dicke superradiance, in which an electronically inverted sample decays collectively, leading to the emission of one or more light pulses in a well-defined direction. Through time-resolved measurements of the superradiant light pulses emitted by an end-pumped BEC, we study the close connection of SLS with Dicke superradiance. A 1D model of the system yields good agreement with the experimental data and shows that the dynamics result from the structures that build up in the light and matter-wave fields along the BEC. This paves the way for exploiting the atom-photon correlations generated by the superradiance.
Scalar field as a Bose-Einstein condensate in a Schwarzschild-de Sitter spacetime
Castellanos, Elías; Lämmerzahl, Claus; Macías, Alfredo
2015-01-01
In this paper we analyze some properties of a scalar field configuration, where it is considered a trapped Bose-Einstein condensate in a Schwarzschild-de Sitter background spacetime. In a natural way, the geometry of the curved spacetime provides an effective trapping potential for the scalar field configuration. This fact allows to explore some thermodynamical properties of the system. Additionally, the curved geometry of the spacetime also induces a position dependent self-interaction parameter, that can be interpreted as a kind of \\emph{gravitational Feshbach resonance}, which could affect the stability of the \\emph{cloud} and could be used to obtain information about the interactions among the components of the system.
Dynamics of vortex dipoles in anisotropic Bose-Einstein condensates
International Nuclear Information System (INIS)
We study the motion of a vortex dipole in a Bose-Einstein condensate confined to an anisotropic trap. We focus on a system of ODEs describing the vortices' motion, which is in turn a reduced model of the Gross-Pitaevskii equation describing the condensate's motion. Using a sequence of canonical changes of variables, we reduce the dimension and simplify the equations of motion. In this study, we uncover two interesting regimes. Near a family of periodic orbits known as guiding centers, we find that the dynamics is essentially that of a pendulum coupled to a linear oscillator, leading to stochastic reversals in the overall direction of rotation of the dipole. Near the separatrix orbit in the isotropic system, we find other families of periodic, quasi-periodic, and chaotic trajectories. In a neighborhood of the guiding center orbits, we derive an explicit iterated map that simplifies the problem further. Numerical calculations are used to illustrate the phenomena discovered through the analysis. Using the results from the reduced system, we are able to construct complex periodic orbits in the original, PDE, mean-field model for Bose-Einstein condensates, which corroborates the phenomenology observed in the reduced dynamical equations
Bose-Einstein graviton condensate in a Schwarzschild black hole
Alfaro, Jorge; Gabbanelli, Luciano
2016-01-01
We analyze in detail a previous proposal by Dvali and G\\'omez that black holes could be treated as consisting of a Bose-Einstein condensate of gravitons. In order to do so we extend the Einstein-Hilbert action with a chemical potential-like term, thus placing ourselves in a grand-canonical ensemble. The form and characteristics of this chemical potential-like piece are discussed in some detail. After this, we proceed to expand the ensuing equations of motion up to second order around the classical Schwarzschild metric so that some non-linear terms in the metric fluctuation are kept. We argue that the resulting equations could be interpreted as the Gross-Pitaevskii equation describing a graviton Bose-Einstein condensate trapped by the black hole gravitational field. Next we search for solutions and, modulo some very plausible assumptions, we find out that the condensate vanishes outside the horizon but is non-zero in its interior. Based on hints from a numerical integration of the equations we formulate an ans...
Analogue gravitational phenomena in Bose-Einstein condensates
Finazzi, Stefano
2012-08-01
Analogue gravity is based on the simple observation that perturbations propagating in several physical systems can be described by a quantum field theory in a curved spacetime. While phenomena like Hawking radiation are hardly detectable in astrophysical black holes, these effects may be experimentally tested in analogue systems. In this Thesis, focusing on Bose-Einstein condensates, we present our recent results about analogue models of gravity from three main perspectives: as laboratory tests of quantum field theory in curved spacetime, for the techniques that they provide to address various issues in general relativity, and as toy models of quantum gravity. The robustness of Hawking-like particle creation is investigated in flows with a single black hole horizon. Furthermore, we find that condensates with two (white and black) horizons develop a dynamical instability known in general relativity as black hole laser effect. Using techniques borrowed from analogue gravity, we also show that warp drives, which are general relativistic spacetimes allowing faster-than-light travel, are unstable. Finally, the cosmological constant issue is investigated from an analogue gravity perspective and relativistic Bose-Einstein condensates are proposed as new analogue systems with novel interesting properties.
Dynamics of vortex dipoles in confined Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
Torres, P.J. [Departamento de Matematica Aplicada, Universidad de Granada, 18071 Granada (Spain); Kevrekidis, P.G., E-mail: kevrekid@gmail.com [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Frantzeskakis, D.J. [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece); Carretero-Gonzalez, R. [Nonlinear Dynamical System Group, Computational Science Research Center, and Department of Mathematics and Statistics, San Diego State University, San Diego, CA 92182-7720 (United States); Schmelcher, P. [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Hall, D.S. [Department of Physics, Amherst College, Amherst, MA 01002-5000 (United States)
2011-08-01
We present a systematic theoretical analysis of the motion of a pair of straight counter-rotating vortex lines within a trapped Bose-Einstein condensate. We introduce the dynamical equations of motion, identify the associated conserved quantities, and illustrate the integrability of the ensuing dynamics. The system possesses a stationary equilibrium as a special case in a class of exact solutions that consist of rotating guiding-center equilibria about which the vortex lines execute periodic motion; thus, the generic two-vortex motion can be classified as quasi-periodic. We conclude with an analysis of the linear and nonlinear stability of these stationary and rotating equilibria. -- Highlights: → A model describing the motion of a vortex dipole in a quasi two-dimensional trapped Bose-Einstein condensate is considered. → The model is integrable and the generic motion of the dipole is quasi-periodic. → Stationary and periodic (guiding-center) equilibria are identified. → Both equilibria are found to be dynamically stable.
Atom Interferometry on Sounding Rockets with Bose-Einstein Condensates
Seidel, Stephan T.; Becker, Dennis; Lachmann, Maike D.; Herr, Waldemar; Rasel, Ernst M.; Quantus Collaboration
2016-05-01
One of the fundamental postulates of our description of nature is the universality of free fall, stating that the force exerted upon an object due to gravity is independent of its constitution. A precise test of this assumption is the comparison of the free fall of two ultra-cold clouds of different atomic species via atom interferometry. Since the sensitivity of the measurement is proportional to the square of the propagation time in the interferometer, it can be increased by performing the experiments in microgravity. In order to fully utilize the potential of the experiments the usage of a Bose-Einstein-Condensate as the initial state is necessary, because it is characterized by a small initial size and a low expansion velocity. As a step towards the transfer of such a system into space three sounding rocket missions with atom interferometers are currently being prepared. The launch of the first mission, aimed at the first demonstration of a Bose-Einstein-Condensate in space and an atom interferometer based on it is planned for 2016 from ESRANGE, Sweden. It will be followed by two more missions that extend the scientific goals to the creation of degenerate mixtures and dual-species atom interferometry. This research is funded by the German Space Agency DLR under Grant Number DLR 50 1131-37.
Bright Solitons in an Atomic Tunnel Array with Either Attractive or Repulsive Atom-Atom Interactions
Institute of Scientific and Technical Information of China (English)
YANG Xiao-Xue; YOU Jun; WU Ying
2004-01-01
@@ Taking a coherent state representation, we derive the nonlinear Schrodinger-type differential-difference equations from the quantized model of an array of traps containing Bose-Einstein condensates and linked by the tunnelling process among the adjacent traps. It is shown that no matter whether two-body interactions among atoms are repulsive or attractive, a nearly uniform atom distribution can evolve into a bright soliton-type localized ensemble of atoms and a lump of atom distribution can also be smeared out by redistributing atoms among traps under appropriate initial phase differences of atoms in adjacent traps. These two important features originate from the tailoring effect of the initial phase conditions in coherent tunnelling processes, which differs crucially from the previous tailoring effect coming mainly from the periodicity of optical lattices.
Bose-Einstein condensation and superfluidity
Pitaevskii, Lev
2016-01-01
This volume introduces the basic concepts of Bose–Einstein condensation and superfluidity. It makes special reference to the physics of ultracold atomic gases; an area in which enormous experimental and theoretical progress has been achieved in the last twenty years. Various theoretical approaches to describing the physics of interacting bosons and of interacting Fermi gases, giving rise to bosonic pairs and hence to condensation, are discussed in detail, both in uniform and harmonically trapped configurations. Special focus is given to the comparison between theory and experiment, concerning various equilibrium, dynamic, thermodynamic, and superfluid properties of these novel systems. The volume also includes discussions of ultracold gases in dimensions, quantum mixtures, and long-range dipolar interactions.
Theory of single-shot phase contrast imaging in spinor Bose-Einstein condensates.
Ilo-Okeke, Ebubechukwu O; Byrnes, Tim
2014-06-13
We introduce a theoretical framework for single-shot phase contrast imaging (PCI) measurements of spinor Bose-Einstein condensates (BECs). Our model allows for the simple calculation of the quantum backaction resulting from the measurement, and the amount of information that is read out. We find that there is an optimum time Gτ ∼ 1/N for the light-matter interaction (G is the ac Stark shift frequency, N is the number of particles in the BEC), where the maximum amount of information can be read out from the BEC. A universal information-disturbance tradeoff law ε(F)ε(G) ∝ 1/N(2) is found where ε(F) is the amount of backaction and ε(G) is the estimation error. The PCI measurement can also be found to be a direct probe of the quantum fluctuations of the BEC, via the noise of the PCI signal.
Theory of single-shot phase contrast imaging in spinor Bose-Einstein condensates
Ilo-Okeke, Ebubechukwu O
2014-01-01
We introduce a theoretical framework for single-shot phase contrast imaging (PCI) measurements of spinor Bose-Einstein condensates. Our model allows for the simple calculation of the quantum backaction resulting from the measurement, and the amount of information that is read out. We find that there is an optimum time $ G\\tau \\sim 1/N $ for the light-matter interaction ($G $ is the ac Stark shift frequency, $ N $ is the number of particles in the BEC), where the maximum amount of information can be read out from the BEC. A universal information-disturbance tradeoff law $ \\epsilon_F \\epsilon_G \\propto 1/N^2 $ is found where $ \\epsilon_F $ is the amount of backaction and $ \\epsilon_G $ is the estimation error. The PCI measurement can also be found to be a direct probe of the quantum fluctuations of the BEC, via the noise of the PCI signal.
Impurity driven Brownian motion of solitons in elongated Bose-Einstein Condensates
Aycock, L M; Genkina, D; Lu, H -I; Galitski, V; Spielman, I B
2016-01-01
Solitons, spatially-localized, mobile excitations resulting from an interplay between nonlinearity and dispersion, are ubiquitous in physical systems from water channels and oceans to optical fibers and Bose-Einstein condensates (BECs). For the first time, we observed and controlled the Brownian motion of solitons. We launched long-lived dark solitons in highly elongated $^{87}\\rm{Rb}$ BECs and showed that a dilute background of impurity atoms in a different internal state dramatically affects the soliton. With no impurities and in one-dimension (1-D), these solitons would have an infinite lifetime, a consequence of integrability. In our experiment, the added impurities scatter off the much larger soliton, contributing to its Brownian motion and decreasing its lifetime. We describe the soliton's diffusive behavior using a quasi-1-D scattering theory of impurity atoms interacting with a soliton, giving diffusion coefficients consistent with experiment.
Dark matter as a Bose-Einstein Condensate: the relativistic non-minimally coupled case
Energy Technology Data Exchange (ETDEWEB)
Bettoni, Dario; Colombo, Mattia; Liberati, Stefano, E-mail: bettoni@sissa.it, E-mail: mattia.colombo@studenti.unitn.it, E-mail: liberati@sissa.it [SISSA, Via Bonomea 265, Trieste, 34136 (Italy)
2014-02-01
Bose-Einstein Condensates have been recently proposed as dark matter candidates. In order to characterize the phenomenology associated to such models, we extend previous investigations by studying the general case of a relativistic BEC on a curved background including a non-minimal coupling to curvature. In particular, we discuss the possibility of a two phase cosmological evolution: a cold dark matter-like phase at the large scales/early times and a condensed phase inside dark matter halos. During the first phase dark matter is described by a minimally coupled weakly self-interacting scalar field, while in the second one dark matter condensates and, we shall argue, develops as a consequence the non-minimal coupling. Finally, we discuss how such non-minimal coupling could provide a new mechanism to address cold dark matter paradigm issues at galactic scales.
Samson, E. C.; Wilson, K. E.; Newman, Z. L.; Anderson, B. P.
2016-02-01
We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles for the superfluid atomic gas; by controlling the positions of the beams within the plane of the BEC, superfluid flow is deterministically established around each beam such that two vortices of opposite circulation are generated by the motion of the beams, with each vortex pinned to the in situ position of a laser beam. We study the vortex creation process, and show that the vortices can be moved about within the BEC by translating the positions of the laser beams. This technique can serve as a building block in future experimental techniques to create, on-demand, deterministic arrangements of few or many vortices within a BEC for precise studies of vortex dynamics and vortex interactions.
Thermalization of the quark-gluon plasma and dynamical formation of Bose-Einstein Condensate
Liao, Jinfeng
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 pre-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 the kinetic approach for describing this highly overpopulated system and find approximate scaling solutions as well as numerically study the onset of condensation. Finally we discuss possible phenomenological implications.
Landau damping of transverse quadrupole oscillations of an elongated Bose-Einstein condensate
International Nuclear Information System (INIS)
We have studied the interaction between the low-lying transverse collective oscillations and the thermal excitations of an elongated Bose-Einstein condensate by means of perturbation theory. We consider a cylindrical trapped condensate and calculate the transverse elementary excitations at zero temperature by solving the linearized Gross-Pitaevskii equations in two dimensions (2D). We use them to calculate the matrix elements between the thermal excited states and the quasi-2D collective modes. The Landau damping of transverse collective modes is studied as a function of temperature. At low temperatures, the corresponding damping rate is in agreement with the experimental data for the decay of the transverse quadrupole mode, but it is too small to explain the observed slow decay of the transverse breathing mode. The reason for this discrepancy is discussed
Levy-Feldgeim distributions for one-dimensional analysis of the Bose-Einstein correlations
Okorokov, V A
2016-01-01
The paper presents the study of relations between parameters of the two central-symmetrical Levy - Feldgeim distributions which can be used for investigation of one-dimensional Bose - Einstein correlations (1D BEC). The systems of equations are suggested for femtoscopic 1D parameters, strength of correlations and radius, in the case of two general view stable distributions for the first time. The relations take into account possible various finite ranges of the Lorentz invariant four-momentum difference for two central-symmetrical Levy - Feldgeim distributions. The systems of transcendental equations are derived for specific case of general view stable distributions most used for experimental study of 1D BEC, namely, for Cauchy and Gauss parameterizations. The mathematical formalism is verified with help of available experimental results for 1D BEC in various processes of strong interaction. The estimations for 1D femtoscopic parameters agree well with experiments in cases of the pair of general central-symme...
Output Rate of Atomic Four-Wave Mixing in Two-Component Bose-Einstein Condensate
Institute of Scientific and Technical Information of China (English)
LI Jia-Hua; LI Wei-Bing; PENG Ju-Cun
2004-01-01
In this letter, following the proposal of Heurich et al. [Phys. Rev. A63 (2001) 033605], we analyze and discuss output rate of atomic four-wave mixing in the two-component Bose-Einstein condensate under the condition of the steady state. The results show that the magnitude of the signal beam increases with the increase of the intensity of the probe beam, up to a saturated value, then it decreases as the probe beam increases. The influence of the interaction range on the signal beam is also predicted. In particular, it is worth while pointing out that in contrast to the previous solutions, our obtained analytical solutions are of very simple and explicit forms, which open the door for further investigating the related physical mechanisms.
Vortex structures of rotating spin-orbit-coupled Bose-Einstein condensates
International Nuclear Information System (INIS)
We consider the quasi-two-dimensional two-component Bose-Einstein condensates with Rashba spin-orbit (SO) coupling in a rotating trap. The rotation angular velocity couples to the mechanical angular momentum, which contains a noncanonical part arising from SO coupling. The effects of an external Zeeman term favoring spin polarization along the radial direction is also considered, which has the same form as the noncanonical part of the mechanical angular momentum. The rotating condensate exhibits a variety of rich structures by varying the strengths of the trapping potential and interaction. With a strong trapping potential, the condensate exhibits a half-quantum vortex-lattice configuration. Such a configuration is driven to the normal one by introducing the external radial Zeeman field. In the case of a weak trap potential, the condensate exhibits a multidomain pattern of plane-wave states under the external radial Zeeman field.
Gravitational Waves as a New Probe of Bose-Einstein Condensate Dark Matter
Dev, P S Bhupal; Ohmer, Sebastian
2016-01-01
There exists a class of ultralight Dark Matter (DM) models which could form a Bose-Einstein condensate (BEC) in the early universe and behave as a single coherent wave instead of individual particles in galaxies. We show that a generic BEC DM halo intervening along the line of sight of a gravitational wave (GW) signal could induce an observable change in the speed of GW, with the effective refractive index depending only on the mass and self-interaction of the constituent DM particles and the GW frequency. Hence, we propose to use the deviation in the speed of GW as a new probe of the BEC DM parameter space. With a multi-messenger approach to GW astronomy and/or with extended sensitivity to lower GW frequencies, the entire BEC DM parameter space can be effectively probed by our new method in the near future.
Thermalization of the quark-gluon plasma and dynamical formation of Bose-Einstein Condensate
International Nuclear Information System (INIS)
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 pre-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 the kinetic approach for describing this highly overpopulated system and find approximate scaling solutions as well as numerically study the onset of condensation. Finally we also discuss possible phenomenological implications.
Quantum Enhancement of the Index of Refraction in a Bose-Einstein Condensate.
Bons, P C; de Haas, R; de Jong, D; Groot, A; van der Straten, P
2016-04-29
We study the index of refraction of an ultracold bosonic gas in the dilute regime. Using phase-contrast imaging with light detuned from resonance by several tens of linewidths, we image a single cloud of ultracold atoms for 100 consecutive shots, which enables the study of the scattering rate as a function of temperature and density using only a single cloud. We observe that the scattering rate is increased below the critical temperature for Bose-Einstein condensation by a factor of 3 compared to the single-atom scattering rate. We show that current atom-light interaction models to second order of the density show a similar increase, where the magnitude of the effect depends on the model that is used to calculate the pair-correlation function. This confirms that the effect of quantum statistics on the index of refraction is dominant in this regime. PMID:27176521
On the observation of nonclassical excitations in Bose-Einstein condensates
Finke, Andreas; Weinfurtner, Silke
2016-01-01
In the recent experimental and theoretical literature well-established nonclassicality criteria from the field of quantum optics have been directly applied to the case of excitations in matter-waves. Among these are violations of Cauchy-Schwarz inequalities, Glauber-Sudarshan P-nonclassicality, sub-Poissonian number-difference squeezing (also known as the two-mode variance) and the criterion of nonseparability. We review the strong connection of these criteria and their meaning in quantum optics, and point out differences in the interpretation between light and matter waves. We then calculate observables for a homogenous Bose-Einstein condensate undergoing an arbitrary modulation in the interaction parameter at finite initial temperature, within both the quantum theory as well as a classical reference. We conclude that to date in experiments relevant for analogue gravity, nonclassical effects have not conclusively been observed and conjecture that additional, noncommuting, observables have to be measured to t...
Half-Quantum Vortices in an Antiferromagnetic Spinor Bose-Einstein Condensate.
Seo, Sang Won; Kang, Seji; Kwon, Woo Jin; Shin, Yong-il
2015-07-01
We report on the observation of half-quantum vortices (HQVs) in the easy-plane polar phase of an antiferromagnetic spinor Bose-Einstein condensate. Using in situ magnetization-sensitive imaging, we observe that pairs of HQVs with opposite core magnetization are generated when singly charged quantum vortices are injected into the condensate. The dynamics of HQV pair formation is characterized by measuring the temporal evolutions of the pair separation distance and the core magnetization, which reveals the short-range nature of the repulsive interactions between the HQVs. We find that spin fluctuations arising from thermal population of transverse magnon excitations do not significantly affect the HQV pair formation dynamics. Our results demonstrate the instability of a singly charged vortex in the antiferromagnetic spinor condensate. PMID:26182102
Impurities as a quantum thermometer for a Bose-Einstein Condensate.
Sabín, Carlos; White, Angela; Hackermuller, Lucia; Fuentes, Ivette
2014-01-01
We introduce a primary thermometer which measures the temperature of a Bose-Einstein Condensate in the sub-nK regime. We show, using quantum Fisher information, that the precision of our technique improves the state-of-the-art in thermometry in the sub-nK regime. The temperature of the condensate is mapped onto the quantum phase of an atomic dot that interacts with the system for short times. We show that the highest precision is achieved when the phase is dynamical rather than geometric and when it is detected through Ramsey interferometry. Standard techniques to determine the temperature of a condensate involve an indirect estimation through mean particle velocities made after releasing the condensate. In contrast to these destructive measurements, our method involves a negligible disturbance of the system. PMID:25241663
Effective mass approach for a Bose-Einstein condensate in an optical lattice
Institute of Scientific and Technical Information of China (English)
DUAN ZhengLu; STEEL M J; XU AiTing; ZHANG WeiPing
2009-01-01
We study the stationary and propagating solutions for a Bose-Einstein condensate (BEC) in a periodic optical potential with an additional confining optical or magnetic potential.Using an effective mass approximation we express the condensate wave function in terms of slowly-varying envelopes modulating the Bloch modes of the optical lattice.In the limit of a weak nonlinearity,we derive a nonlinear Schr(o)dinger equation for propagation of the envelope function which does not contain the rapid oscillation of the lattice.We then consider the ground state solutions in detail in the regime of weak,moderate and strong nonlinear interactions.We describe the form of solution which is appropriate in each regime,and place careful limits on the validity of each type of solution.Finally we extend the study to the propagating dynamics of a spinor atomic BEC in an optical lattice and some interesting phenomena are revealed.
Spin-orbit angular momentum coupling in a spin-1 Bose-Einstein condensate
Chen, Li; Pu, Han; Zhang, Yunbo
2016-01-01
We propose a simple model with spin and orbit angular momentum coupling in a spin-1 Bose-Einstein condensate, where three internal atomic states are Raman coupled by a pair of copropagating Laguerre-Gaussian beams. The resulting Raman transition imposes a transfer of orbital angular momentum between photons and the condensate in a spin-dependent way. Focusing on a regime where the single-particle ground state is nearly threefold degenerate, we show that the weak interatomic interaction in the condensate produces a rich phase diagram, and that a many-body Rabi oscillation between two quantum phases can be induced by a sudden quench of the quadratic Zeeman shift. We carried out our calculations using both a variational method and a full numerical method, and found excellent agreement.
Quantum Enhancement of the Index of Refraction in a Bose-Einstein Condensate.
Bons, P C; de Haas, R; de Jong, D; Groot, A; van der Straten, P
2016-04-29
We study the index of refraction of an ultracold bosonic gas in the dilute regime. Using phase-contrast imaging with light detuned from resonance by several tens of linewidths, we image a single cloud of ultracold atoms for 100 consecutive shots, which enables the study of the scattering rate as a function of temperature and density using only a single cloud. We observe that the scattering rate is increased below the critical temperature for Bose-Einstein condensation by a factor of 3 compared to the single-atom scattering rate. We show that current atom-light interaction models to second order of the density show a similar increase, where the magnitude of the effect depends on the model that is used to calculate the pair-correlation function. This confirms that the effect of quantum statistics on the index of refraction is dominant in this regime.
Tunneling Dynamics of Two-Species Bose-Einstein Condensates with Feshbach Resonances
Institute of Scientific and Technical Information of China (English)
CHEN Chang-Yong
2003-01-01
We investigate tunneling dynamics of atomic group consisting of three atoms in Bose-Einstein condensateswith Feshbach resonance. It is shown that the tunneling of the atom group depends not only on the inter-atomicnonlinear interactions and the initial number of atoms in these condensates, but also on the tunneling coupling betweenthe atomic condensate and the three-atomic molecular condensate. It is found that besides oscillating tunneling currentbetween the atomic condensate and the molecular condensate, the nonlinear atomic group tunneling dynamics sustains aself-maintained population imbalance: a macroscopic quantum self-trapping effect. The influence of de-coherence causedby non-condensate atoms on the tunneling dynamics is studied. It is indicated that de-coherence suppresses the atomicgroup tunneling.
Tunneling Dynamics of Two-Species Bose-Einstein Condensates with Feshbach Resonances
Institute of Scientific and Technical Information of China (English)
CHENChanu-Yonu
2003-01-01
We investigate tunneling dynamics of atomic group consisting of three atoms in Bose-Einstein condensates with Feshbach resonance. It is shown that the tunneling of the atom group depends not only on the inter-atomic nonlinear interactions and the initial number of atoms in these condensates, but also on the tunneling coupling between the atomic condensate and the three-atomic molecular condensate. It is found that besides oscillating tunneling current between the atomic condensate and the molecular condensate, the nonlinear atomic group tunneling dynamics sustains a self-maintained 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 indicated that de-coherence suppresses the atomic group tunneling.
Interferometry with non-classical motional states of a Bose-Einstein condensate
van Frank, S.; Negretti, A.; Berrada, T.; Bücker, R.; Montangero, S.; Schaff, J.-F.; Schumm, T.; Calarco, T.; Schmiedmayer, J.
2014-05-01
The Ramsey interferometer is a prime example of precise control at the quantum level. It is usually implemented using internal states of atoms, molecules or ions, for which powerful manipulation procedures are now available. Whether it is possible to control external degrees of freedom of more complex, interacting many-body systems at this level remained an open question. Here we demonstrate a two-pulse Ramsey-type interferometer for non-classical motional states of a Bose-Einstein condensate in an anharmonic trap. The control sequences used to manipulate the condensate wavefunction are obtained from optimal control theory and are directly optimized to maximize the interferometric contrast. They permit a fast manipulation of the atomic ensemble compared to the intrinsic decay processes and many-body dephasing effects. This allows us to reach an interferometric contrast of 92% in the experimental implementation.
The spin evolution of spin-3 52Cr Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
situ Shu-Ping; He Yan-Zhang
2011-01-01
This paper studies theoretically the spin evolution of a Bose-Einstein condensate starting from a mixture of two or three groups of 52Cr (spin-3) atoms in an optical trap. The initial state is so chosen that the condensate has total magnetization zero so that the system does not distinguish up and down. It is assumed that the system is very dilute (particle number is very small), the temperature is very low, and the frequency of the harmonic trap is large enough.In these situations, the deviation caused by the neglect of the dipole-dipole interaction and by using the single-mode approximation is reduced. A theoretical calculation beyond the mean field theory is performed and the numerical results are helpful for the evaluation of the unknown strength go.
Schegelsky, V A
2016-01-01
Bose-Einstein correlations in proton-proton collisions at the LHC are well descried by the formula with two different scales. It is shown for the first time that the pions are produced by few small size sources distributed over a much larger area in impact parameter space occupied by the interaction amplitude. The dependence of the two radii obtained in this procedure on the charged particle density and the mean transverse momentum of the pion/hadron in the correlated pair are discussed.
Bloch oscillations and mean-field effects of Bose-Einstein condensates in 1D optical lattices.
Morsch, O; Müller, J H; Cristiani, M; Ciampini, D; Arimondo, E
2001-10-01
We have loaded Bose-Einstein condensates into one-dimensional, off-resonant optical lattices and accelerated them by chirping the frequency difference between the two lattice beams. For small values of the lattice well depth, Bloch oscillations were observed. Reducing the potential depth further, Landau-Zener tunneling out of the lowest lattice band, leading to a breakdown of the oscillations, was also studied and used as a probe for the effective potential resulting from mean-field interactions as predicted by Choi and Niu [Phys. Rev. Lett. 82, 2022 (1999)]. The effective potential was measured for various condensate densities and trap geometries, yielding good qualitative agreement with theoretical calculations.
Dynamics of Spin-2 Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
We numerically simulate the dynamics of a spin-2 Bose-Einstein condensate. We find that the initial phase plays an important role in the spin component oscillations. The spin mixing processes can fully cancel out due to quantum interference when taking some initial special phase. In all the spin mixing processes, the total spin is conversed.When the initial population is mainly occupied by a component with the maximal or minimal magnetic quantum number,the oscillations of spin components cannot happen due to the total spin conversation. The presence of quadratic Zeeman energy terms suppresses some spin mixing processes so that the oscillations of spin components are suppressed in some initial spin configuration. However, the linear Zecman energy terms have no effects on the spin mixing processes.
Stabilization of ring dark solitons in Bose-Einstein condensates
International Nuclear Information System (INIS)
Earlier work has shown that ring dark solitons in two-dimensional Bose-Einstein condensates are generically unstable. In this work, we propose a way of stabilizing the ring dark soliton via a radial Gaussian external potential. We investigate the existence and stability of the ring dark soliton upon variations of the chemical potential and also of the strength of the radial potential. Numerical results show that the ring dark soliton can be stabilized in a suitable interval of external potential strengths and chemical potentials. Furthermore, we also explore different proposed particle pictures considering the ring as a moving particle and find, where appropriate, results in very good qualitative and also reasonable quantitative agreement with the numerical findings
Breathing Bright Solitons in a Bose-Einstein Condensate
Institute of Scientific and Technical Information of China (English)
崇桂书; 海文华; 谢琼涛
2003-01-01
A Bose-Einstein condensate with time varying scattering length in time-dependent harmonic trap is analytically investigated and soliton-like solutions of the Gross-Pitaeviskii equation are obtained to describe single soliton,bisoliton and N-soliton properties of the matter wave. The influences of the geometrical property and modulate frequency of trapping potential on soliton behaviour are discussed. When the trap potential has a very small trap aspect ratio or oscillates with a high frequency, the matter wave preserves its shape nearly like a soliton train in propagation, while the breathing behaviour, which displays the periodic collapse and revival of the matter wave,is found for a relatively large aspect ratio or slow varying potential. Meanwhile mass centre of the matter wave translates and/or oscillates for different trap aspect ratio and trap frequencies.
Kinetic approach to a relativistic Bose-Einstein condensate
Meistrenko, Alex; Zhou, Kai; Greiner, Carsten
2015-01-01
We apply a Boltzmann approach to the kinetic regime of a relativistic Bose-Einstein condensate of scalar bosons by decomposing the one-particle distribution function in a condensate part and a non-zero momentum part of excited modes, leading to a coupled set of evolution equations which are then solved efficiently with an adaptive higher order Runge-Kutta scheme. We compare our results to the partonic cascade Monte-Carlo simulation BAMPS for an underpopulated but far from equilibrium case of massless bosons. Motivated by the color glass condensate initial conditions in QCD with a strongly overpopulated initial glasma state, we also discuss the time evolution starting from an overpopulated initial distribution function of massive scalar bosons.
Scanning Cryogenic Magnetometry with a 1D Bose Einstein Condensate
Straquadine, Joshua; Yang, Fan; Lev, Benjamin
We present a novel scanning probe magnetometer suitable for cryogenic studies, in which the probe is a Bose-Einstein condensate of 87Rb. The system is designed for rapid sample changes and operation between 35 K and room temperature while remaining compatible with the UHV requirements of ultracold atom experiments. We demonstrate a spatial resolution (FWHM) of 2.6 μm and a repeatability of 1.9 +/- 1.0 nT. We also show that the system is operating close to the fundamental measurement limits set by photon shot noise and atom shot noise. Our scanning quantum cryogenic atom microscope is suitable for fundamental studies of transport and magnetism in condensed matter systems such as high-temperature superconductors and topological insulators. We discuss the advantages and applications of this magnetometry technique.
Stagflation -- Bose-Einstein condensation in the early universe
Takeshi, Fukuyama
2009-01-01
Our universe experienced the accelerated expansion at least twice; an extreme inflationary acceleration in the early universe and the recent mild acceleration. By introducing the Bose-Einstein condensation (BEC) phase of a boson field, we have been developing a unified model of dark energy (DE) and dark matter (DM) for the later mild acceleration. In this scenario, two phases of BEC (=DE) and normal gas (=DM) transform with each other through BEC phase transition. This unified model has successfully explained the mild acceleration as an attractor. We extend this BEC cosmology to the early universe without introducing new ingredients. In this scenario, the inflation is naturally initiated by the condensation of the bosons in the huge vacuum energy. This inflation and even the cosmic expansion eventually terminates exactly at zero energy density. We call this stage as stagflation. At this stagflation era, particle production and the decay of BEC take place. The former makes the universe turn into the standard h...
Bose-Einstein condensation of alkaline earth atoms: ;{40}Ca.
Kraft, Sebastian; Vogt, Felix; Appel, Oliver; Riehle, Fritz; Sterr, Uwe
2009-09-25
We have achieved Bose-Einstein condensation of ;{40}Ca, the first for an alkaline earth element. The influence of elastic and inelastic collisions associated with the large ground-state s-wave scattering length of ;{40}Ca was measured. From these findings, an optimized loading and cooling scheme was developed that allowed us to condense about 2 x 10;{4} atoms after laser cooling in a two-stage magneto-optical trap and subsequent forced evaporation in a crossed dipole trap within less than 3 s. The condensation of an alkaline earth element opens novel opportunities for precision measurements on the narrow intercombination lines as well as investigations of molecular states at the ;{1}S-;{3}P asymptotes. PMID:19905493
Spontaneous symmetry breaking in spinor Bose-Einstein condensates
DEFF Research Database (Denmark)
Scherer, Manuel; Lücke, Bernd; Peise, Jan;
2013-01-01
We present an analytical model for the theoretical analysis of spin dynamics and spontaneous symmetry breaking in a spinor Bose-Einstein condensate (BEC). This allows for an excellent intuitive understanding of the processes and provides good quantitative agreement with the experimental results...... of Scherer et al. [ Phys. Rev. Lett. 105 135302 (2010)]. It is shown that the dynamics of a spinor BEC initially prepared in an unstable Zeeman state mF=0 (|0〉) can be understood by approximating the effective trapping potential for the state |±1〉 with a cylindrical box potential. The resonances....... In addition, a detailed account of the experimental methods for the preparation and analysis of spinor quantum gases is given....
On relativistic particle creation in Bose-Einstein condensates
Sabín, Carlos
2014-01-01
We show that particle creation of Bogoliubov modes in a Bose-Einstein condensate due to the accelerated motion of the trap is a genuinely relativistic effect. To this end we show that Bogoliubov modes can be described by a time rescaling of the Minkowski metric. A consequence of this is that Rindler transformations are perceived by the phonons as generalised Rindler transformations where the speed of light is replaced by the speed of sound, enhancing particle creation at small velocities. Since the non-relativistic limit of a Rindler transformation is just a Galilean transformation entailing no length contraction or time dilation, we show that the effect vanishes in the non-relativistic limit.
Newton's cradle analogue with Bose-Einstein condensates
Franzosi, Roberto; Vaia, Ruggero
2014-05-01
We propose a possible experimental realization of a quantum analogue of Newton's cradle using a configuration which starts from a Bose-Einstein condensate. The system consists of atoms with two internal states trapped in a one-dimensional tube with a longitudinal optical lattice and maintained in a strong Tonks-Girardeau regime at maximal filling. In each site the wave-function is a superposition of the two atomic states and a disturbance of the wave-function propagates along the chain in analogy with the propagation of momentum in the classical Newton cradle. The quantum travelling signal is generally deteriorated by dispersion, which is large for a uniform chain and is known to be zero for a suitably engineered chain, but the latter is hardly realizable in practice. Starting from these opposite situations we show how the coherent behaviour can be enhanced with minimal experimental effort.
Power spectrum for the Bose-Einstein condensate dark matter
Energy Technology Data Exchange (ETDEWEB)
Velten, Hermano, E-mail: velten@physik.uni-bielefeld.de [Departamento de Fisica, UFES, Vitoria, 29075-910 Espirito Santo (Brazil); Fakultaet fuer Physik, Universitaet Bielefeld, Postfach 100131, 33501 Bielefeld (Germany); Wamba, Etienne [Laboratory of Mechanics, Department of Physics, Faculty of Science, University of Yaounde I, P.O. Box 812, Yaounde (Cameroon)
2012-03-13
We assume that dark matter is composed of scalar particles that form a Bose-Einstein condensate (BEC) at some point during the cosmic evolution. Afterwards, cold dark matter is in the form of a condensate and behaves slightly different from the standard dark matter component. We study the large scale perturbative dynamics of the BEC dark matter in a model where this component coexists with baryonic matter and cosmological constant. The perturbative dynamics is studied using neo-Newtonian cosmology (where the pressure is dynamically relevant for the homogeneous and isotropic background) which is assumed to be correct for small values of the sound speed. We show that BEC dark matter effects can be seen in the matter power spectrum if the mass of the condensate particle lies in the range 15 MeV
Dark-bright ring solitons in Bose-Einstein condensates
Energy Technology Data Exchange (ETDEWEB)
Stockhofe, J; Schmelcher, P [Zentrum fuer Optische Quantentechnologien, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Kevrekidis, P G [Department of Mathematics and Statistics, University of Massachusetts, Amherst MA 01003-4515 (United States); Frantzeskakis, D J, E-mail: jstockho@physnet.uni-hamburg.de, E-mail: kevrekid@math.umass.edu [Department of Physics, University of Athens, Panepistimiopolis, Zografos, Athens 157 84 (Greece)
2011-10-14
We study dark-bright (DB) ring solitons in two-component Bose-Einstein condensates. In the limit of large densities of the dark component, we describe the soliton dynamics by means of an equation of motion for the ring radius. The presence of the bright, 'filling' species is demonstrated to have a stabilizing effect on the ring dark soliton. Near the linear limit, we discuss the symmetry-breaking bifurcations of DB soliton stripes and vortex-bright soliton clusters from the DB ring and relate the stabilizing effect of filling to changes in the bifurcation diagram. Finally, we show that the stabilization by means of a second component is not limited to the radially symmetric structures, but can also be observed in a cross-like DB soliton configuration. (fast track communication)
Quantum mass acquisition in spinor Bose-Einstein condensates.
Phuc, Nguyen Thanh; Kawaguchi, Yuki; Ueda, Masahito
2014-12-01
Quantum mass acquisition, in which a massless (quasi)particle becomes massive due to quantum corrections, is predicted to occur in several subfields of physics. However, its experimental observation remains elusive since the emergent energy gap is too small. We show that a spinor Bose-Einstein condensate is an excellent candidate for the observation of such a peculiar phenomenon as the energy gap turns out to be 2 orders of magnitude larger than the zero-point energy. This extraordinarily large energy gap is a consequence of the dynamical instability. The propagation velocity of the resultant massive excitation mode is found to be decreased by the quantum corrections as opposed to phonons. PMID:25526104
Spatial structure of a collisionally inhomogeneous Bose-Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
Li, Fei, E-mail: wiself@gmail.com [Hunan First Normal University, Department of Education Science (China); Zhang, Dongxia; Rong, Shiguang; Xu, Ying [Hunan University of Science and Technology, Department of Physics (China)
2013-11-15
The spatial structure of a collisionally inhomogeneous Bose-Einstein condensate (BEC) in an optical lattice is studied. A spatially dependent current with an explicit analytic expression is found in the case with a spatially dependent BEC phase. The oscillating amplitude of the current can be adjusted by a Feshbach resonance, and the intensity of the current depends heavily on the initial and boundary conditions. Increasing the oscillating amplitude of the current can force the system to pass from a single-periodic spatial structure into a very complex state. But in the case with a constant phase, the spatially dependent current disappears and the Melnikov chaotic criterion is obtained via a perturbative analysis in the presence of a weak optical lattice potential. Numerical simulations show that a strong optical lattice potential can lead BEC atoms to a state with a chaotic spatial distribution via a quasiperiodic route.
Bell correlations in a Bose-Einstein condensate.
Schmied, Roman; Bancal, Jean-Daniel; Allard, Baptiste; Fadel, Matteo; Scarani, Valerio; Treutlein, Philipp; Sangouard, Nicolas
2016-04-22
Characterizing many-body systems through the quantum correlations between their constituent particles is a major goal of quantum physics. Although entanglement is routinely observed in many systems, we report here the detection of stronger correlations--Bell correlations--between the spins of about 480 atoms in a Bose-Einstein condensate. We derive a Bell correlation witness from a many-particle Bell inequality involving only one- and two-body correlation functions. Our measurement on a spin-squeezed state exceeds the threshold for Bell correlations by 3.8 standard deviations. Our work shows that the strongest possible nonclassical correlations are experimentally accessible in many-body systems and that they can be revealed by collective measurements. PMID:27102479
Black Hole Horizons and Bose-Einstein Condensation
Ferrari, Frank
2016-01-01
Consider a particle sitting at a fixed position outside of a stable black hole. If the system is heated up, the black hole horizon grows and there should exist a critical temperature above which the particle enters the black hole interior. We solve a simple model describing exactly this situation: a large N matrix quantum mechanics modeling a fixed D-particle in a black hole background. We show that indeed a striking phenomenon occurs: above some critical temperature, there is a non-perturbative Bose-Einstein condensation of massless strings. The transition, even though precisely defined by the presence of the condensate, cannot be sharply detected by measurements made in a finite amount of time. The order parameter is fundamentally non-local in time and corresponds to infinite-time correlations.
Vortex formation by merging multiple trapped Bose-Einstein condensates
Weiler, Chad; Neely, Tyler; Scherer, David; Anderson, Brian
2007-06-01
We have experimentally studied the merging of three trapped Bose-Einstein condensates. We find that, depending on the rate of merging, the final single BEC may contain a single vortex core (for slow merging rates), or multiple cores (for fast merging rates). Similarly, a triple-well trap may initiate the formation of three isolated BECs, but if the barriers between the wells are weak enough, the condensates merge together during their growth; this process can also lead to the formation of vortices in the final BEC. We interpret both scenarios in terms of interference between the initial uncorrelated condensates with indeterminate relative phases. We will discuss the results and interpretation of this experiment (D.R. Scherer, C.N. Weiler, T.W. Neely, B.P. Anderson, cond-mat/0610187, to be published in Phys. Rev. Lett.).
The Gross-Pitaevskii equation and Bose-Einstein condensates
Rogel-Salazar, J.
2013-03-01
The Gross-Pitaevskii equation (GPE) is discussed at the level of an advanced course on statistical physics. In the standard literature the GPE is usually obtained in the framework of the second quantization formalism, which in many cases goes beyond the material covered in many advanced undergraduate courses. In this paper, we motivate the derivation of the GPE in relationship to concepts from statistical physics, highlighting a number of applications from the dynamics of a Bose-Einstein condensate to the excitations of the gas cloud. This paper may be helpful for encouraging the discussion of modern developments in a statistical mechanics course, and can also be of use in other contexts such as mathematical physics and modelling. The paper is suitable for undergraduate and graduate students, as well as for general physicists.
Planck, Photon Statistics, and Bose-Einstein Condensation
Greenberger, Daniel M; Scully, Marlan O; Svidzinsky, Anatoly A; Zubairy, M Suhail
2007-01-01
The interplay between optical and statistical physics is a rich and exciting field of study. Black body radiation was the first application of photon statistics, although it was initially treated as a problem of the cavity oscillators in equilibrium with the photon field. However Planck surprisingly resisted the idea that anything physical would be quantized for a long time after he had solved the problem. We trace this development. Then, after the invention of the laser itself, it proved difficult to develop a theory of laser action that could account for photon statistics, i.e. fluctuations near threshold. This was accomplished in 1965. After Bose-Einstein condensation was successfully achieved, the same problem arose in this case. The fluctuation problem had not been treated adequately even for the ideal Bose gas. However this problem has now been solved using the same techniques as in the theory of laser action.
Ex Vacuo Atom Chip Bose-Einstein Condensate (BEC)
Squires, Matthew B; Kasch, Brian; Stickney, James A; Erickson, Christopher J; Crow, Jonathan A R; Carlson, Evan J; Burke, John H
2016-01-01
Ex vacuo atom chips, used in conjunction with a custom thin walled vacuum chamber, have enabled the rapid replacement of atom chips for magnetically trapped cold atom experiments. Atoms were trapped in $>2$ kHz magnetic traps created using high power atom chips. The thin walled vacuum chamber allowed the atoms to be trapped $\\lesssim1$ mm from the atom chip conductors which were located outside of the vacuum system. Placing the atom chip outside of the vacuum simplified the electrical connections and improved thermal management. Using a multi-lead Z-wire chip design, a Bose-Einstein condensate was produced with an external atom chip. Vacuum and optical conditions were maintained while replacing the Z-wire chip with a newly designed cross-wire chip. The atom chips were exchanged and an initial magnetic trap was achieved in less than three hours.
Scanning Cryogenic Magnetometry with a Bose-Einstein Condensate
Straquadine, Joshua; Yang, Fan; Lev, Benjamin
2016-05-01
Microscopy techniques co-opted from nonlinear optics and high energy physics have complemented solid-state probes in elucidating exotic order manifest in condensed matter systems. We present a novel scanning magnetometer which adds the techniques of ultracold atomic physics to the condensed matter toolbox. Our device, the Scanning Quantum CRyogenic Atom Microscope (SQCRAMscope) uses a one-dimensional Bose-Einstein condensate of 87 Rb to image magnetic and electric fields near surfaces between room and cryogenic temperatures, and allows for rapid sample changes while retaining UHV compatibility for atomic experiments. We present our characterization of the spatial resolution and magnetic field sensitivity of the device, and discuss the advantages and applications of this magnetometry technique. In particular, we will discuss our plans for performing local transport measurements in technologically relevant materials such as Fe-based superconductors and topological insulators.
Matter-wave recombiners for trapped Bose-Einstein condensates
Berrada, T.; van Frank, S.; Bücker, R.; Schumm, T.; Schaff, J.-F.; Schmiedmayer, J.; Julía-Díaz, B.; Polls, A.
2016-06-01
Interferometry with trapped atomic Bose-Einstein condensates (BECs) requires the development of techniques to recombine the two paths of the interferometer and map the accumulated phase difference to a measurable atom number difference. We have implemented and compared two recombining procedures in a double-well-based BEC interferometer. The first procedure utilizes the bosonic Josephson effect and controlled tunneling of atoms through the potential barrier, similar to laser light in an optical fiber coupler. The second one relies on the interference of the reflected and transmitted parts of the BEC wave function when impinging on the potential barrier, analogous to light impinging on a half-silvered mirror. Both schemes were implemented successfully, yielding an interferometric contrast of ˜20 % and 42% respectively. Building efficient matter-wave recombiners represents an important step towards the coherent manipulation of external quantum superposition states of BECs.
Bell correlations in a Bose-Einstein condensate.
Schmied, Roman; Bancal, Jean-Daniel; Allard, Baptiste; Fadel, Matteo; Scarani, Valerio; Treutlein, Philipp; Sangouard, Nicolas
2016-04-22
Characterizing many-body systems through the quantum correlations between their constituent particles is a major goal of quantum physics. Although entanglement is routinely observed in many systems, we report here the detection of stronger correlations--Bell correlations--between the spins of about 480 atoms in a Bose-Einstein condensate. We derive a Bell correlation witness from a many-particle Bell inequality involving only one- and two-body correlation functions. Our measurement on a spin-squeezed state exceeds the threshold for Bell correlations by 3.8 standard deviations. Our work shows that the strongest possible nonclassical correlations are experimentally accessible in many-body systems and that they can be revealed by collective measurements.
Kinetic approach to a relativistic Bose-Einstein condensate.
Meistrenko, Alex; van Hees, Hendrik; Zhou, Kai; Greiner, Carsten
2016-03-01
We apply a Boltzmann approach to the kinetic regime of a relativistic Bose-Einstein condensate of scalar bosons by decomposing the one-particle distribution function in a condensate part and a nonzero momentum part of excited modes, leading to a coupled set of evolution equations which are then solved efficiently with an adaptive higher order Runge-Kutta scheme. We compare our results to the partonic cascade Monte Carlo simulation BAMPS for a critical but far from equilibrium case of massless bosons. Motivated by the color glass condensate initial conditions in QCD with a strongly overpopulated initial glasma state, we also discuss the time evolution starting from an overpopulated initial distribution function of massive scalar bosons. In this system a self-similar evolution of the particle cascade with a nonrelativistic turbulent scaling in the infrared sector is observed as well as a relativistic exponent for the direct energy cascade, confirming a weak wave turbulence in the ultraviolet region.
Analogue gravitational phenomena in Bose-Einstein condensates
Finazzi, Stefano
2012-01-01
Analogue gravity is based on the simple observation that perturbations propagating in several physical systems can be described by a quantum field theory in a curved spacetime. While phenomena like Hawking radiation are hardly detectable in astrophysical black holes, these effects may be experimentally tested in analogue systems. In this Thesis, focusing on Bose-Einstein condensates, we present our recent results about analogue models of gravity from three main perspectives: as laboratory tests of quantum field theory in curved spacetime, for the techniques that they provide to address various issues in general relativity, and as toy models of quantum gravity. The robustness of Hawking-like particle creation is investigated in flows with a single black hole horizon. Furthermore, we find that condensates with two (white and black) horizons develop a dynamical instability known in general relativity as black hole laser effect. Using techniques borrowed from analogue gravity, we also show that warp drives, which...
Bose-Einstein condensation of dipolar excitons in quantum wells
Energy Technology Data Exchange (ETDEWEB)
Timofeev, V B; Gorbunov, A V, E-mail: timofeev@issp.ac.r [Institute of Solid State Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow region (Russian Federation)
2009-02-01
The experiments on Bose-Einstein condensation (BEC) of dipolar (spatially-indirect) excitons in the lateral traps in GaAs/AlGaAs Schottky-diode heterostructures with double and single quantum wells are presented. The condensed part of dipolar excitons under detection in the far zone is placed in k-space in the range which is almost two orders of magnitude less than thermal exciton wave vector. BEC occurs spontaneously in a reservoir of thermalized excitons. Luminescence images of Bose-condensate of dipolar excitons exhibit along perimeter of circular trap axially symmetrical spatial structures of equidistant bright spots which strongly depend on excitation power and temperature. By means of two-beam interference experiments with the use of cw and pulsed photoexcitation it was found that the state of dipolar exciton Bose-condensate is spatially coherent and the whole patterned luminescence configuration in real space is described by a common wave function.
Laser controlling chaotic region of a two-component Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
Boli Xia; Wenhua Hai
2005-01-01
@@ For a weakly and periodically driven two-component Bose-Einstein condensate (BEC) the Melnikov chaotic solution and boundedness conditions are derived from a direct perturbation theory that leads to the chaotic regions in the parameter space.
Institute of Scientific and Technical Information of China (English)
LIU Shi-Kuo; GAO Bin; FU Zun-Tao; LIU Shi-Da
2009-01-01
In this paper, applying the dependent and independent variables transformations as well as the Jacobi elliptic function expansion method, the envelope periodic solutions to one-dimensional Gross-Pitaevskii equation in Bose-Einstein condensates are obtained.
Dynamics of a quantum phase transition in a ferromagnetic Bose-Einstein condensate
Damski, Bogdan; Zurek, Wojciech H.
2007-01-01
We discuss dynamics of a slow quantum phase transition in a spin-1 Bose-Einstein condensate. We determine analytically the scaling properties of the system magnetization and verify them with numerical simulations in a one dimensional model.
Nonexponential motional damping of impurity atoms in Bose-Einstein condensates
Mazets, I. E.; Kurizki, G.
2004-01-01
We demonstrate that the damping of the motion of an impurity atom injected at a supercritical velocity into a Bose-Einstein condensate can exhibit appreciable deviation from the exponential law on time scales of $10^{-5}$ s.
A Variational Sum-Rule Approach to Collective Excitations of a Trapped Bose-Einstein Condensate
Kimura, Takashi; Saito, Hiroki; Ueda, Masahito
1998-01-01
It is found that combining an excitation-energy sum rule with Fetter's trial wave function gives almost exact low-lying collective-mode frequencies of a trapped Bose-Einstein condensate at zero temperature.
Currents algebra for an atom-molecule Bose-Einstein condensate model
Filho, Gilberto N. Santos
2016-01-01
I present an interconversion currents algebra for an atom-molecule Bose-Einstein condensate model and use it to get the quantum dynamics of the currents. For different choices of the Hamiltonian parameters I get different currents dynamics.
Vortex Rings and Mutual Drag in Trapped Bose-Einstein Condensates
Jackson, B.; McCann, J F; Adams, C. S.
1999-01-01
We study the drag on an object moving through a trapped Bose-Einstein condensate, and show that finite compressibility leads to a mutual drag, which is subsequently suppressed by the formation of a vortex ring.
Internal Vortex Structure of a Trapped Spinor Bose-Einstein Condensate
Yip, S. -K.
1999-01-01
The internal vortex structure of a trapped spin-1 Bose-Einstein condensate is investigated. It is shown that it has a variety of configurations depending on, in particular, the ratio of the relevant scattering lengths and the total magnetization.
You, Jhih-Shih; Liu, I.-Kang; Wang, Daw-Wei; Gou, Shih-Chuan; Wu, Congjun
2016-05-01
In the context of Gross-Pitaevskii theory, we investigate the unconventional Bose-Einstein condensations in the two-species mixture with p -wave symmetry in the second band of a bipartite optical lattice. An imaginary-time propagation method is developed to numerically determine the p -orbital condensation. Different from the single-species case, the two-species boson mixture exhibits two nonequivalent complex condensates in the intraspecies-interaction-dominating regime, exhibiting the vortex-antivortex lattice configuration in the charge and spin channels, respectively. When the interspecies interaction is tuned across the SU(2) invariant point, the system undergoes a quantum phase transition toward a checkerboardlike spin-density wave state with a real-valued condensate wave function. The influence of lattice asymmetry on the quantum phase transition is addressed. Finally, we present a phase-sensitive measurement scheme for experimentally detecting the unconventional Bose-Einstein condensation in our model.
Phase structure of Bose - Einstein condensate in ultra-cold Bose gases
International Nuclear Information System (INIS)
The Bose-Einstein condensation of ultra-cold Bose gases in studied by means of the Cornwall-Jackiw-Tomboulis effective potential approach in the improved double - bubble approximation which preserves the Goldstone theorem. The phase structure of Bose-Einstein condensate associating with two different types of phase transition is systematically investigated. Its main feature is that the symmetry which was broken at zero temperature gets restored at higher temperature. (author)
Observation of F = 2 Spinor Bose-Einstein Condensation in a Magnetic Field
Institute of Scientific and Technical Information of China (English)
MA Xiu-Quan; CHEN Shuai; YANG Fan; XIA Lin; ZHOU Xiao-Ji; WANG Yi-Qiu; CHEN Xu-Zong
2005-01-01
@@ Multiple-component Bose-Einstein condensation has been observed in a magnetic field generated by a controllable magnetic quadrupole-Ioffe-configuration trap. Different distributions of atoms in spinor Bose-Einstein condensates are created by changing the time difference of switching-off current in quadrupole-Ioffe-configuration coils and bias coils of the magnetic trap. A simple analysis is carried out to explain some phenomena of the experiment.
Generation of linear waves in the flow of Bose-Einstein condensate past an obstacle
Gladush, Yu. G.; Kamchatnov, A. M.
2007-01-01
The theory of linear wave structures generated in Bose-Einstein condensate flow past an obstacle is developed. The shape of wave crests and dependence of amplitude on coordinates far enough from the obstacle are calculated. The results are in good agreement with the results of numerical simulations obtained earlier. The theory gives a qualitative description of experiments with Bose-Einstein condensate flow past an obstacle after condensate's release from a trap.
Two characteristic temperatures for a Bose-Einstein condensate of a finite number of particles
Idziaszek, Z.; Rzazewski, K.
2003-01-01
We consider two characteristic temperatures for a Bose-Einstein condensate, that are related to certain properties of the condensate statistics. We calculate them for an ideal gas confined in power-law traps and show that they approach the critical temperature in the limit of large number of particles. The considered characteristic temperatures can be useful in the studies of Bose-Einstein condensates of a finite number of atoms, indicating the point of a phase transition.
Macroscopic Entanglement of a Bose Einstein Condensate on a Superconducting Atom Chip
Singh, Mandip
2007-01-01
We propose and analyse a practically implementable scheme to generate macroscopic entanglement of a Bose-Einstein condensate in a micro-magnetic trap magnetically coupled to a superconducting loop. We treat the superconducting loop in a quantum superposition of two different flux states coupled with the magnetic trap to generate macroscopic entanglement. Our scheme also provides a platform to realise interferometry of entangled atoms through the Bose-Einstein condensate and to explore physics...
Laser-induced Rotation of a Trapped Bose-Einstein Condensate
Marzlin, Karl-Peter; Zhang, Weiping
1997-01-01
In this letter, atom optic techniques are proposed to control the excitation of a Bose-Einstein condensate in an atomic trap. We show that by employing the dipole potential induced by four highly detuned travelling-wave laser beams with appropriate phases and frequencies, one can coherently excite a trapped Bose-Einstein condensate composed of ultracold alkali atoms into a state rotating around the trap center. The connection to vortex states is discussed.
Vortex Stability Near the Surface of a Bose-Einstein Condensate
Khawaja, U. Al
2003-01-01
We investigate energetic stability of vortices near the surface of a Bose-Einstein condensate. From an energy functional of a rotating Bose-Einstein condensate, written in terms of variables local to the surface, and a suitable trial wavefunction we calculate the energy of a moving vortex. The energetic stability of the vortex is investigated in terms of the rotation frequency of the confining potential. The critical frequency at which the vortices enter the condensate is calculated and compa...
Composite structure of vortices in two-component Bose-Einstein condensate
Ivashin Anatoly P.; Poluektov Yuri M.
2015-01-01
In contrast to one-component Bose-Einstein condensate case, the vortices in two-component condensate can have various complicated structures. The vortices in a space-homogeneous Bose-Einstein condensate have been studied in this paper. It is shown that the vortex structure is described by three dimensionless parameters. This is totally different from the usual one-component condensate case,where an isolated vortex is described by a parameterless dimensionless equation....
Ground state properties of a Bose-Einstein condensate confined in an anharmonic external potential
Institute of Scientific and Technical Information of China (English)
Wang Deng-Long; Yan Xiao-Hong; Tang Yi
2004-01-01
In light of the interference experiment of Bose-Einstein condensates, we present an anharmonic external potential model to study ground state properties of Bose-Einstein condensates. The ground state energy and the chemical potential have been analytically obtained, which are lower than those in harmonic trap. Additionally, it is found that the anharmonic strength of the external potential has an important effect on density and velocity distributions of the ground state for the Thomas-Fermi model.
Dark matter as the Bose-Einstein condensation in loop quantum cosmology
Atazadeh, K.; Darabi, F.; M. Mousavi
2016-01-01
We consider the FLRW universe in a loop quantum cosmological model filled with the radiation, baryonic matter (with negligible pressure), dark energy and dark matter. The dark matter sector is supposed to be of Bose-Einstein condensate type. The Bose-Einstein condensation process in a cosmological context by supposing it as an approximate first order phase transition, has been already studied in the literature. Here, we study the evolution of the physical quantities related to the early unive...
Production and measurement of Bose-Einstein condensate of 87Rb atomic gas
Institute of Scientific and Technical Information of China (English)
2008-01-01
The research platform for Bose-Einstein condensate in 87 Rb atomic gas,which is composed of a double MOT configuration and a QUIC trap,was reported.The properties of the condensate were measured both in time-of-flight and in tight confinement by the absorption imaging method.The measurements agreed with the criterions of Bose-Einstein condensation phase transition.About 2×10 5 atoms were pure condensed.
Measurement of Bose-Einstein Correlations in $e^{+}e^{-}\\to W^{+}W^{-}$ Events at LEP
Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M
2002-01-01
Bose-Einstein correlations in W-pair production at LEP are investigated in a data sample of 629 pb$^{-1}$ collected by the L3 detector at $\\sqrt{s}=$ 189--209\\,GeV. Bose-Einstein correlations between pions within a W decay are observed and found to be in good agreement with those in light-quark Z decay. No evidence is found for Bose-Einstein correlations between hadrons coming from different W's in the same event.
Thin accretion disks around cold Bose-Einstein condensate stars
International Nuclear Information System (INIS)
Due to their superfluid properties some compact astrophysical objects, like neutron or quark stars, may contain a significant part of their matter in the form of a Bose-Einstein condensate (BEC). Observationally distinguishing between neutron/quark stars and BEC stars is a major challenge for this latter theoretical model. An observational possibility of indirectly distinguishing BEC stars from neutron/quark stars is through the study of the thin accretion disks around compact general relativistic objects. In the present paper, we perform a detailed comparative study of the electromagnetic and thermodynamic properties of the thin accretion disks around rapidly rotating BEC stars, neutron stars and quark stars, respectively. Due to the differences in the exterior geometry, the thermodynamic and electromagnetic properties of the disks (energy flux, temperature distribution, equilibrium radiation spectrum, and efficiency of energy conversion) are different for these classes of compact objects. Hence in this preliminary study we have pointed out some astrophysical signatures that may allow one to observationally discriminate between BEC stars and neutron/quark stars. (orig.)
Rotation curves in Bose-Einstein Condensate Dark Matter Halos
Dwornik, M; Gergely, L Á
2013-01-01
The study of the rotation curves of spiral galaxies reveals a nearly constant cored density distribution of Cold Dark Matter. N-body simulations however lead to a cuspy distribution on the galactic scale, with a central peak. A Bose-Einstein condensate (BEC) of light particles naturally solves this problem by predicting a repulsive force, obstructing the formation of the peak. After succinctly presenting the BEC model, we test it against rotation curve data for a set of 3 High Surface Brightness (HSB), 3 Low Surface Brightness (LSB) and 3 dwarf galaxies. The BEC model gives a similar fit to the Navarro-Frenk-White (NFW) dark matter model for all HSB and LSB galaxies in the sample. For dark matter dominated dwarf galaxies the addition of the BEC component improved more upon the purely baryonic fit than the NFW component. Thus despite the sharp cut-off of the halo density, the BEC dark matter candidate is consistent with the rotation curve data of all types of galaxies.
Stagflation: Bose-Einstein condensation in the early universe
Fukuyama, Takeshi; Morikawa, Masahiro
2009-09-01
Our universe experienced the accelerated expansion at least twice; an extreme inflationary acceleration in the early universe and the recent mild acceleration. By introducing the Bose-Einstein condensation (BEC) phase of a boson field, we have been developing a unified model of dark energy (DE) and dark matter (DM) for the later mild acceleration. In this scenario, two phases of BEC (=DE) and normal gas (=DM) transform with each other through BEC phase transition. This unified model has successfully explained the mild acceleration as an attractor. We extend this BEC cosmology to the early universe without introducing new ingredients. In this scenario, the inflation is naturally initiated by the condensation of the bosons in the huge vacuum energy. This inflation and even the cosmic expansion eventually terminates exactly at zero energy density. We call this stage as stagflation. At this stagflation era, particle production and the decay of BEC take place. The former makes the universe turn into the standard hot big bang stage and the latter makes the cosmological constant vanishingly small after the inflation. Furthermore, we calculate the density fluctuations produced in this model, which turns out to be in the range allowed by the present observational data. We also show that the stagflation is quite robust and easily appears when one allows negative region of the potential. Further, we comment on the possibility that BEC generation/decay series might have continued all the time in the cosmic history from the inflation to present.
Emergent gravitational dynamics in relativistic Bose--Einstein condensate
Belenchia, Alessio; Mohd, Arif
2014-01-01
Analogue models of gravity have played a pivotal role in the past years by providing a test bench for many open issues in quantum field theory in curved spacetime such as the robustness of Hawking radiation and cosmological particle production. More recently, the same models have offered a valuable framework within which current ideas about the emergence of spacetime and its dynamics could be discussed via convenient toy models. In this context, we study here an analogue gravity system based on a relativistic Bose--Einstein condensate. We show that in a suitable limit this system provides not only an example of an emergent spacetime (with a massive and a massless relativistic fields propagating on it) but also that such spacetime is governed by an equation with geometric meaning that takes the familiar form of Nordstr{\\"o}m theory of gravitation. In this equation the gravitational field is sourced by the expectation value of the trace of the effective stress energy tensor of the quasiparticles while the Newto...
Thin accretion disks around cold Bose-Einstein condensate stars
Energy Technology Data Exchange (ETDEWEB)
Danila, Bogdan [Babes-Bolyai University, Department of Physics, Cluj-Napoca (Romania); Harko, Tiberiu [University College London, Department of Mathematics, London (United Kingdom); Kovacs, Zoltan
2015-05-15
Due to their superfluid properties some compact astrophysical objects, like neutron or quark stars, may contain a significant part of their matter in the form of a Bose-Einstein condensate (BEC). Observationally distinguishing between neutron/quark stars and BEC stars is a major challenge for this latter theoretical model. An observational possibility of indirectly distinguishing BEC stars from neutron/quark stars is through the study of the thin accretion disks around compact general relativistic objects. In the present paper, we perform a detailed comparative study of the electromagnetic and thermodynamic properties of the thin accretion disks around rapidly rotating BEC stars, neutron stars and quark stars, respectively. Due to the differences in the exterior geometry, the thermodynamic and electromagnetic properties of the disks (energy flux, temperature distribution, equilibrium radiation spectrum, and efficiency of energy conversion) are different for these classes of compact objects. Hence in this preliminary study we have pointed out some astrophysical signatures that may allow one to observationally discriminate between BEC stars and neutron/quark stars. (orig.)
Subsonic and Supersonic Effects in Bose-Einstein Condensate
Zak, Michail
2003-01-01
A paper presents a theoretical investigation of subsonic and supersonic effects in a Bose-Einstein condensate (BEC). The BEC is represented by a time-dependent, nonlinear Schroedinger equation that includes terms for an external confining potential term and a weak interatomic repulsive potential proportional to the number density of atoms. From this model are derived Madelung equations, which relate the quantum phase with the number density, and which are used to represent excitations propagating through the BEC. These equations are shown to be analogous to the classical equations of flow of an inviscid, compressible fluid characterized by a speed of sound (g/Po)1/2, where g is the coefficient of the repulsive potential and Po is the unperturbed mass density of the BEC. The equations are used to study the effects of a region of perturbation moving through the BEC. The excitations created by a perturbation moving at subsonic speed are found to be described by a Laplace equation and to propagate at infinite speed. For a supersonically moving perturbation, the excitations are found to be described by a wave equation and to propagate at finite speed inside a Mach cone.
Recent experiments with ring Bose-Einstein condensates
Eckel, S.; Kumar, A.; Anderson, N. W.; Campbell, G. K.
2016-05-01
Here, we present three recent results of our experiments with ring-shaped 23 Na Bose-Einstein condensates. First, we present results of the effect of temperature on the decay of persistent currents in the presence of a local, stationary perturbation, or weak link. When the weak link rotates, it can drive transitions between quantized persistent current states in the ring, that form hysteresis loops whose size depends strongly on temperature. We find that our data does not fit with a simple model of thermal activation. Second, we present a new method to measure the quantized persistent current state of the ring in a minimally-destructive way. This technique uses phonons as probes of the background flow through the Doppler effect. Finally, we present a set of experiments designed to reproduce the horizon problem in the early universe. Supersonic expansion of the ring creates causally-disconnected regions of BEC whose phase evolves at different rates. When the expansion stops and these regions are allowed to recombine, they form topological excitations. These excitations can be predicted using a simple theory that shows excellent agreement with the data.
Elements of Vortex-Dipole Dynamics in a Nonuniform Bose-Einstein Condensate
Sakhel, Roger R.; Sakhel, Asaad R.
2016-09-01
The elements of the vortex-dipole (VD) dynamics are numerically examined in a nonuniform Bose-Einstein condensate (BEC) using the time-dependent Gross-Pitaevskii equation that is solved by the split-step Crank-Nicolson method in real time. The BEC is trapped in a harmonic potential, surrounded by a hard-wall box potential, and stirred by an attractive focusing laser. In this regard, we particularly refer to a recent examination by Aioi et al. (Phys. Rev. X, 1: 021003, 2011) who presented controlled VD generation using a red laser in an infinite homogeneous BEC for comparison. It is found that the dynamics in the present nonuniform BEC is quite different from the one reported earlier by Aioi et al. The elements considered are the phase maps that demonstrate the presence of phase rings, the effects of the coupling constant on the vortex lifetime, the density at the vortex core, and the heating effects of the stirrer. Upon a suitable choice of coupling for our system, a VD generated by the moving fragment is transferred to and trapped by the central BEC cloud. The latter serves as a dissipationless vortex respository, where the lifetime of the VD is extended on demand. An analytical model is presented that qualitatively reproduces the wavefunction with its principle features and provides details inaccessible by the present numerical method such as the coupling between stirrer and BEC.
Elements of Vortex-Dipole Dynamics in a Nonuniform Bose-Einstein Condensate
Sakhel, Roger R.; Sakhel, Asaad R.
2016-06-01
The elements of the vortex-dipole (VD) dynamics are numerically examined in a nonuniform Bose-Einstein condensate (BEC) using the time-dependent Gross-Pitaevskii equation that is solved by the split-step Crank-Nicolson method in real time. The BEC is trapped in a harmonic potential, surrounded by a hard-wall box potential, and stirred by an attractive focusing laser. In this regard, we particularly refer to a recent examination by Aioi et al. (Phys. Rev. X, 1: 021003, 2011) who presented controlled VD generation using a red laser in an infinite homogeneous BEC for comparison. It is found that the dynamics in the present nonuniform BEC is quite different from the one reported earlier by Aioi et al. The elements considered are the phase maps that demonstrate the presence of phase rings, the effects of the coupling constant on the vortex lifetime, the density at the vortex core, and the heating effects of the stirrer. Upon a suitable choice of coupling for our system, a VD generated by the moving fragment is transferred to and trapped by the central BEC cloud. The latter serves as a dissipationless vortex respository, where the lifetime of the VD is extended on demand. An analytical model is presented that qualitatively reproduces the wavefunction with its principle features and provides details inaccessible by the present numerical method such as the coupling between stirrer and BEC.
Tunable Polarons of Slow-Light Polaritons in a Two-Dimensional Bose-Einstein Condensate
Grusdt, Fabian; Fleischhauer, Michael
2016-02-01
When an impurity interacts with a bath of phonons it forms a polaron. For increasing interaction strengths the mass of the polaron increases and it can become self-trapped. For impurity atoms inside an atomic Bose-Einstein condensate (BEC) the nature of this transition is not understood. While Feynman's variational approach to the Fröhlich model predicts a sharp transition for light impurities, renormalization group studies always predict an extended intermediate-coupling region characterized by large phonon correlations. To investigate this intricate regime and to test polaron physics beyond the validity of the Fröhlich model we suggest a versatile experimental setup that allows us to tune both the mass of the impurity and its interactions with the BEC. The impurity is realized as a dark-state polariton (DSP) inside a quasi-two-dimensional BEC. We show that its interactions with the Bogoliubov phonons lead to photonic polarons, described by the Bogoliubov-Fröhlich Hamiltonian, and make theoretical predictions using an extension of a recently introduced renormalization group approach to Fröhlich polarons.
Tunable Polarons of Slow-Light Polaritons in a Two-Dimensional Bose-Einstein Condensate.
Grusdt, Fabian; Fleischhauer, Michael
2016-02-01
When an impurity interacts with a bath of phonons it forms a polaron. For increasing interaction strengths the mass of the polaron increases and it can become self-trapped. For impurity atoms inside an atomic Bose-Einstein condensate (BEC) the nature of this transition is not understood. While Feynman's variational approach to the Fröhlich model predicts a sharp transition for light impurities, renormalization group studies always predict an extended intermediate-coupling region characterized by large phonon correlations. To investigate this intricate regime and to test polaron physics beyond the validity of the Fröhlich model we suggest a versatile experimental setup that allows us to tune both the mass of the impurity and its interactions with the BEC. The impurity is realized as a dark-state polariton (DSP) inside a quasi-two-dimensional BEC. We show that its interactions with the Bogoliubov phonons lead to photonic polarons, described by the Bogoliubov-Fröhlich Hamiltonian, and make theoretical predictions using an extension of a recently introduced renormalization group approach to Fröhlich polarons. PMID:26894712
Dynamic fragmentation in a quenched two-mode Bose-Einstein condensate
Wu, Shu-Yuan; Zhong, Hong-Hua; Huang, Jia-Hao; Qin, Xi-Zhou; Lee, Chao-Hong
2016-06-01
We investigate the fragmentation in a two-mode Bose-Einstein condensate with Josephson coupling. We explore how the fragmentation and entropy of the ground state depend on the intermode asymmetry and interparticle interactions. Owing to the interplay between the asymmetry and the interactions, a sequence of notches and plateaus in the fragmentation appears with the single-atom tunneling and interaction blockade, respectively. We then analyze the dynamical properties of the fragmentation in three typical quenches of the asymmetry: linear, sudden, and periodic quenches. In a linear quench, the final state is a fragmented state due to the sequential Landau-Zener tunneling, which can be analytically explained by applying the two-level Landau-Zener formula for each avoided level crossing. In a sudden quench, the fragmentation exhibits persistent fluctuations that sensitively depend on the interparticle interactions and intermode coupling. In a periodic quench, the fragmentation is modulated by the periodic driving, and a suitable modulation may allow one to control the fragmentation.
Gravitational, lensing, and stability properties of Bose-Einstein condensate dark matter halos
Harko, Tiberiu
2015-01-01
The possibility that dark matter, whose existence is inferred from the study of the galactic rotation curves and from the mass deficit in galaxy clusters, can be in a form of a Bose-Einstein condensate has recently been extensively investigated. In the present work, we consider a detailed analysis of the astrophysical properties of the Bose-Einstein condensate dark matter halos that could provide clear observational signatures and help discriminate between different dark matter models. In the Bose-Einstein condensation model dark matter can be described as a non-relativistic, gravitationally confined Newtonian gas, whose density and pressure are related by a polytropic equation of state with index $n=1$. The mass and the gravitational properties of the condensate halos are obtained in a systematic form, including the mean logarithmic slopes of the density and of the tangential velocity. Furthermore, the lensing properties of the condensate dark matter are also investigated in detail. In particular, a general ...
Bose-Einstein correlations in W-pair production at LEP
van Dalen, J A
2000-01-01
A report is given on a study of Bose-Einstein correlations in W-pair production at square root (s)=189 GeV with the L3 detector at LEP. In particular, Bose-Einstein correlations are investigated in W/sup +/W /sup -/ overlap and the possible existence of these correlations between particles coming from different W's, which may influence the W mass measurements in the four-jet channel e/sup +/e/sup -/ to W/sup +/W/sup -/ to q/sub 1/q/sub 2/q/sub 3/q/sub 4/. No evidence for such an inter-W Bose-Einstein correlation is found. These results are preliminary. (11 refs).
Magnetic Surface Microtraps for Two-Species Bose-Einstein Condensations
Institute of Scientific and Technical Information of China (English)
胡建军; 印建平
2002-01-01
We propose a novel magnetic surface microtrap (i.e. a double Z-wire trap) for the study of two-species Bose Einstein condensations. The spatial distributions of the magnetic fields from the double Z-wire configurations and their gradients and curvatures are calculated and analysed. The result shows that the proposed surface trap has double magnetic wells and can be continuously changed into a single-well trap by reducing the current in a straight wire, and the maximum field gradient greater than 5 × 104 G/cm and the maximum field curvature (at each trap centre) greater than 2.5 × 107 G/cm2 can be generated in our double-well traps, which can be used to realize two-species Bose-Einstein condensations and to study the properties of double-well Bose-Einstein condensations and so on.
Cavity-Optomechanics with Spin-Orbit Coupled Spinor Bose-Einstein Condensate
Yasir, Kashif Ammar
2015-01-01
Cavity-optomechanics, an exploitation of mechanical-effects of light to couple optical-field with mechanical-objects, has made remarkable progress. Besides, spin-orbit (SO)-coupling, interaction between spin of a quantum-particle and its momentum, has provided foundation to analyze various phenomena like spin-Hall effect and topological-insulators. However, SO-coupling and corresponding topological-features have not been examined in optical-cavity with one vibrational-mirror. Here we report cavity-optomechanics with SO-coupled Bose-Einstein condensate, inducing non-Abelian gauge-field in cavity. We ascertain the influences of SO-coupling and long-range atomic-interactions on low-temperature dynamics which can be experimentally measured by maneuvering area underneath density-noise spectrum. It is detected that not only optomechanical-coupling is modifying topological properties of atomic dressed-states but SO-coupling induced topological-effects are also enabling us to control effective-temperature of mechanic...
Creating full-Bloch Bose-Einstein condensates with Raman q-plates
Schultz, Justin T.; Hansen, Azure; Murphree, Joseph D.; Jayaseelan, Maitreyi; Bigelow, Nicholas P.
2016-06-01
A coherent two-photon optical Raman interaction in a pseudo-spin-1/2 Bose-Einstein condensate (BEC) serves as a q-plate for atoms, converting spin to orbital angular momentum. This Raman q-plate has a singular pattern in its polarization distribution in analogy to the singular birefringent q-plates used in singular optics. The vortex winding direction and magnitude as well as the final spin state of the BEC depend on the initial spin state and the topology of the optical Raman q-plate beams. Drawing on the mathematical and geometric foundations of singular optics, we derive the equivalent Jones matrix for this Raman q-plate and use it to create and characterize atomic spin singularities in the BEC that are analogous to optical C-point singularities in polarization. By tuning the optical Raman parameters, we can generate a coreless vortex spin texture which contains every possible superposition in a two-state system. We identify this spin texture as a full-Bloch BEC since every point on the Bloch sphere is represented at some point in the cross section of the atomic cloud. This spin-orbit interaction and the spin textures it generates may allow for the observation of interesting geometric phases in matter waves and lead to schemes for topological quantum computation with spinor BECs.
Spin Hall effect in a spinor dipolar Bose-Einstein condensate
Oshima, T.; Kawaguchi, Y.
2016-05-01
We theoretically show that the spin Hall effect arises in a Bose-Einstein condensate (BEC) of neutral atoms interacting via the magnetic dipole-dipole interactions (MDDIs). Since the MDDI couples the total spin angular momentum and the relative orbital angular momentum of two colliding atoms, it works as a spin-orbit coupling. Thus, when we prepare a BEC in a magnetic sublevel m =0 , thermally and quantum-mechanically excited atoms in the m =1 and -1 states feel the Lorentz-like forces in the opposite directions. This is the origin for the emergence of the spin Hall effect. We define the mass-current and spin-current operators from the equations of continuity and calculate the spin Hall conductivity from the off-diagonal current-current correlation function within the Bogoliubov approximation. We find that the correction of the current operators due to the MDDI significantly contributes to the spin Hall conductivity. A possible experimental situation is also discussed.
Rashba-type spin-orbit coupling in bilayer Bose-Einstein condensates
Su, S.-W.; Gou, S.-C.; Sun, Q.; Wen, L.; Liu, W.-M.; Ji, A.-C.; Ruseckas, J.; JuzeliÅ«nas, G.
2016-05-01
We explore a way of producing the Rashba spin-orbit coupling (SOC) for ultracold atoms by using a two-component (spinor) atomic Bose-Einstein condensate (BEC) confined in a bilayer geometry. The SOC of the Rashba type is created if the atoms pick up a π phase after completing a cyclic transition between four combined spin-layer states composed of two spin and two layer states. The cyclic coupling of the spin-layer states is carried out by combining an intralayer Raman coupling and an interlayer laser assisted tunneling. We theoretically determine the ground-state phases of the spin-orbit-coupled BEC for various strengths of the atom-atom interaction and the laser-assisted coupling. It is shown that the bilayer scheme provides a diverse ground-state phase diagram. In an intermediate range of the atom-light coupling two interlacing lattices of half-skyrmions and half-antiskyrmions are spontaneously created. In the strong-coupling regime, where the SOC of the Rashba type is formed, the ground state represents plane-wave or standing-wave phases depending on the interaction between the atoms. A variational analysis is shown to be in good agreement with the numerical results.
Exotic vortex lattices in a rotating binary dipolar Bose-Einstein condensate.
Zhang, Xiao-Fei; Wen, Lin; Dai, Cai-Qing; Dong, Rui-Fang; Jiang, Hai-Feng; Chang, Hong; Zhang, Shou-Gang
2016-01-01
In the last decade, considerable advances have been made in the investigation of dipolar quantum gases. Previous theoretical investigations of a rotating binary dipolar Bose-Einstein condensate, where only one component possesses dipole moment, were mainly focused on two special orientations of the dipoles: perpendicular or parallel to the plane of motion. Here we study the ground-state and rotational properties of such a system for an arbitrary orientation of the dipoles. We demonstrate the ground-state vortex structures depend strongly on the relative strength between dipolar and contact interactions and the rotation frequency, as well as on the orientation of the dipoles. In the absence of rotation, the tunable dipolar interaction can be used to induce the squeezing or expansion of the cloud, and to derive the phase transition between phase coexistence and separation. Under finite rotation, the system is found to exhibit exotic ground-state vortex configurations, such as kernel-shell, vortex necklace, and compensating stripe vortex structures. We also check the validity of the Feynman relation, and find no significant deviations from it. The obtained results open up alternate ways for the quantum control of dipolar quantum gases. PMID:26778736
Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps.
Zhang, Xiao-Fei; Han, Wei; Wen, Lin; Zhang, Peng; Dong, Rui-Fang; Chang, Hong; Zhang, Shou-Gang
2015-01-01
Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures. PMID:25731962
Apparatus to image ultra-cold impurities in Bose-Einstein condensates
Cadotte, Andrew; Anderson, David; Sapiro, Rachel; Miller, Stephanie; Raithel, Georg
2012-06-01
We present an experimental apparatus with enhanced ion imaging capabilities relative to our previously used set-ups. The apparatus will be employed to study interactions between ultra-cold impurities and Bose-Einstein condensates (BEC). Atoms will first be loaded into a primary Magneto-optical trap (MOT), which loads a secondary MOT, and then into a quadrupole-Ioffe-configuration (QUIC) trap, where a BEC is formed. Free ultra-cold ions will be made by photoionizing a few atoms. Stray electric fields are canceled by an electrode package surrounding the BEC-ion interaction region. The electric field of a sharp needle (tip diameter 125 microns) is used to generate highly magnified ion images. In our poster, we will discuss expected phenomena, which include quantum charge diffusion [R. Cote, E. Bodo, P. Zhang, and A. Dalgarno], mesoscopic molecular ion formation [R. Cote, V. Kharchenko, and M.D. Lukin, Massignan, C.J. Pethick, and H. Smith], ion self-trapping [R.M. Kalas and D. Blume], and ultra-cold plasma expansion (in the classical domain). We will show details of the experimental apparatus, which is in its final assembly stage.
Skyrmionic vortex lattices in coherently coupled three-component Bose-Einstein condensates
Orlova, Natalia V.; Kuopanportti, Pekko; Milošević, Milorad V.
2016-08-01
We show numerically that a harmonically trapped and coherently Rabi-coupled three-component Bose-Einstein condensate can host unconventional vortex lattices in its rotating ground state. The discovered lattices incorporate square and zig-zag patterns, vortex dimers and chains, and doubly quantized vortices, and they can be quantitatively classified in terms of a skyrmionic topological index, which takes into account the multicomponent nature of the system. The exotic ground-state lattices arise due to the intricate interplay of the repulsive density-density interactions and the Rabi couplings as well as the ubiquitous phase frustration between the components. In the frustrated state, domain walls in the relative phases can persist between some components even at strong Rabi coupling, while vanishing between others. Consequently, in this limit the three-component condensate effectively approaches a two-component condensate with only density-density interactions. At intermediate Rabi coupling strengths, however, we face unique vortex physics that occurs neither in the two-component counterpart nor in the purely density-density-coupled three-component system.
Clark, Kevin B
2010-03-01
Fringe quantum biology theories often adopt the concept of Bose-Einstein condensation when explaining how consciousness, emotion, perception, learning, and reasoning emerge from operations of intact animal nervous systems and other computational media. However, controversial empirical evidence and mathematical formalism concerning decoherence rates of bioprocesses keep these frameworks from satisfactorily accounting for the physical nature of cognitive-like events. This study, inspired by the discovery that preferential attachment rules computed by complex technological networks obey Bose-Einstein statistics, is the first rigorous attempt to examine whether analogues of Bose-Einstein condensation precipitate learned decision making in live biological systems as bioenergetics optimization predicts. By exploiting the ciliate Spirostomum ambiguum's capacity to learn and store behavioral strategies advertising mating availability into heuristics of topologically invariant computational networks, three distinct phases of strategy use were found to map onto statistical distributions described by Bose-Einstein, Fermi-Dirac, and classical Maxwell-Boltzmann behavior. Ciliates that sensitized or habituated signaling patterns to emit brief periods of either deceptive 'harder-to-get' or altruistic 'easier-to-get' serial escape reactions began testing condensed on initially perceived fittest 'courting' solutions. When these ciliates switched from their first strategy choices, Bose-Einstein condensation of strategy use abruptly dissipated into a Maxwell-Boltzmann computational phase no longer dominated by a single fittest strategy. Recursive trial-and-error strategy searches annealed strategy use back into a condensed phase consistent with performance optimization. 'Social' decisions performed by ciliates showing no nonassociative learning were largely governed by Fermi-Dirac statistics, resulting in degenerate distributions of strategy choices. These findings corroborate
Clark, Kevin B
2010-03-01
Fringe quantum biology theories often adopt the concept of Bose-Einstein condensation when explaining how consciousness, emotion, perception, learning, and reasoning emerge from operations of intact animal nervous systems and other computational media. However, controversial empirical evidence and mathematical formalism concerning decoherence rates of bioprocesses keep these frameworks from satisfactorily accounting for the physical nature of cognitive-like events. This study, inspired by the discovery that preferential attachment rules computed by complex technological networks obey Bose-Einstein statistics, is the first rigorous attempt to examine whether analogues of Bose-Einstein condensation precipitate learned decision making in live biological systems as bioenergetics optimization predicts. By exploiting the ciliate Spirostomum ambiguum's capacity to learn and store behavioral strategies advertising mating availability into heuristics of topologically invariant computational networks, three distinct phases of strategy use were found to map onto statistical distributions described by Bose-Einstein, Fermi-Dirac, and classical Maxwell-Boltzmann behavior. Ciliates that sensitized or habituated signaling patterns to emit brief periods of either deceptive 'harder-to-get' or altruistic 'easier-to-get' serial escape reactions began testing condensed on initially perceived fittest 'courting' solutions. When these ciliates switched from their first strategy choices, Bose-Einstein condensation of strategy use abruptly dissipated into a Maxwell-Boltzmann computational phase no longer dominated by a single fittest strategy. Recursive trial-and-error strategy searches annealed strategy use back into a condensed phase consistent with performance optimization. 'Social' decisions performed by ciliates showing no nonassociative learning were largely governed by Fermi-Dirac statistics, resulting in degenerate distributions of strategy choices. These findings corroborate
Properties of spin-orbit-coupled Bose-Einstein condensates
Zhang, Yongping; Mossman, Maren Elizabeth; Busch, Thomas; Engels, Peter; Zhang, Chuanwei
2016-06-01
The experimental and theoretical research of spin-orbit-coupled ultracold atomic gases has advanced and expanded rapidly in recent years. Here, we review some of the progress that either was pioneered by our own work, has helped to lay the foundation, or has developed new and relevant techniques. After examining the experimental accessibility of all relevant spin-orbit coupling parameters, we discuss the fundamental properties and general applications of spin-orbit-coupled Bose-Einstein condensates (BECs) over a wide range of physical situations. For the harmonically trapped case, we show that the ground state phase transition is a Dicke-type process and that spin-orbit-coupled BECs provide a unique platform to simulate and study the Dicke model and Dicke phase transitions. For a homogeneous BEC, we discuss the collective excitations, which have been observed experimentally using Bragg spectroscopy. They feature a roton-like minimum, the softening of which provides a potential mechanism to understand the ground state phase transition. On the other hand, if the collective dynamics are excited by a sudden quenching of the spin-orbit coupling parameters, we show that the resulting collective dynamics can be related to the famous Zitterbewegung in the relativistic realm. Finally, we discuss the case of a BEC loaded into a periodic optical potential. Here, the spin-orbit coupling generates isolated flat bands within the lowest Bloch bands whereas the nonlinearity of the system leads to dynamical instabilities of these Bloch waves. The experimental verification of this instability illustrates the lack of Galilean invariance in the system.
Operator Representation of Fermi-Dirac and Bose-Einstein Integral Functions with Applications
Directory of Open Access Journals (Sweden)
M. Aslam Chaudhry
2007-01-01
Full Text Available Fermi-Dirac and Bose-Einstein functions arise as quantum statistical distributions. The Riemann zeta function and its extension, the polylogarithm function, arise in the theory of numbers. Though it might not have been expected, these two sets of functions belong to a wider class of functions whose members have operator representations. In particular, we show that the Fermi-Dirac and Bose-Einstein integral functions are expressible as operator representations in terms of themselves. Simpler derivations of previously known results of these functions are obtained by their operator representations.
Frequency depending permittivity of the Coulomb system with Bose-Einstein condensate
Bobrov, V B
2015-01-01
The second-order singularity is found in the low-frequency region of the permittivity of a homogeneous and isotropic system of charged particles consisting of electrons and boson nuclei. This singularity is caused by the existence of a Bose-Einstein condensate for nuclei. The result obtained leads to the existence of the "nuclei superconductivity", which can be experimentally verified in superfluid He II. The results of the proposed an experiment can be considered as a direct proof of the existence of a Bose-Einstein condensate in superfluid He II.
Quantum noise of a Bose-Einstein condensate in an optical cavity, correlations and entanglement
Szirmai G.; Nagy D.; Domokos P.
2010-01-01
A Bose-Einstein condensate of ultracold atoms inside the field of a laser-driven optical cavity exhibits dispersive optical bistability. We describe this system by using mean-field approximation and by analyzing the correlation functions of the linearized quantum fluctuations around the mean-field solution. The entanglement and the statistics of the atom-field quadratures are given in the stationary state. It is shown that the mean-field solution, i.e. the Bose-Einstein condensate is robust a...
Ground State and Single Vortex for Bose-Einstein Condensates in Anisotropic Traps
Institute of Scientific and Technical Information of China (English)
XU Zhi-Jun; CAI Ping-Gen
2007-01-01
For Bose-Einstein condensation of neutral atoms in anisotropic traps at zero temperature, we present simple analytical methods for computing the properties of ground state and single vortex of Bose-Einstein condensates,and compare those results to extensive numerical simulations. The critical angular velocity for production of vortices is calculated for both positive and negative scattering lengths a, and find an analytical expression for the large-N limit of the vortex critical angular velocity for a ＞ 0, and the critical number for condensate population approaches the point of collapse for a ＜ 0, by using approximate variational method.
Nonlinear transport of Bose-Einstein condensates in a double barrier potential
Institute of Scientific and Technical Information of China (English)
Fang Jian-Shu
2008-01-01
The stable nonlinear transport of the Bose-Einstein condensates through a double barrier potential in a waveguide is studied.By using the direct perturbation method we have obtained a perturbed solution of Gross-Pitaevskii equation.Theoretical analysis reveals that this perturbed solution is a stable periodic solution,which shows that the transport of Bose-Einstein condensed atoms in this system is a stable nonlinear transport.The corresponding numerical results are in good agreement with the theoretical analytical results.
Dujardin, Julien; Engl, Thomas; Schlagheck, Peter
2016-01-01
We study the transport of an interacting Bose-Einstein condensate through a 1D correlated disorder potential. We use for this purpose the truncated Wigner method, which is, as we show, corresponding to the diagonal approximation of a semiclassical van Vleck-Gutzwiller representation of this many-body transport process. We also argue that semiclassical corrections beyond this diagonal approximation are vanishing under disorder average, thus confirming the validity of the truncated Wigner method in this context. Numerical calculations show that, while for weak atom-atom interaction strengths Anderson localization is preserved with a slight modification of the localization length, for larger interaction strengths a crossover to a delocalized regime exists due to inelastic scattering. In this case, the transport is fully incoherent.
SO(2)-induced breathing patterns in multicomponent Bose-Einstein condensates
Charalampidis, E. G.; Wang, Wenlong; Kevrekidis, P. G.; Frantzeskakis, D. J.; Cuevas-Maraver, J.
2016-06-01
In this work, we employ the SO (2 ) rotations of a two-component, one-, two-, and three-dimensional nonlinear Schrödinger system at and near the Manakov limit to construct vector solitons and vortex structures. In this way, stable stationary dark-bright solitons and their higher-dimensional siblings are transformed into robust oscillatory dark-dark solitons (and generalizations thereof) with and without a harmonic confinement. By analogy to the one-dimensional case, vector higher-dimensional structures take the form of vortex-vortex states in two dimensions and, e.g., vortex-ring-vortex-ring ones in three dimensions. We consider the effects of unequal (self- and cross-) interaction strengths, where the SO (2 ) symmetry is only approximately satisfied, showing the dark-dark soliton oscillation is generally robust. Similar features are found in higher dimensions too, although our examples suggest that phenomena such as phase separation may contribute to the associated dynamics. These results, in connection with the experimental realization of one-dimensional variants of such states in optics and Bose-Einstein condensates, suggest the potential observability of the higher-dimensional bound states proposed herein.
Fermion spectrum of Bose-Fermi-Hubbard model in the phase with Bose-Einstein condensate
International Nuclear Information System (INIS)
We investigate the fermion spectrum within the Bose- Fermi-Hubbard model used for the description of boson-fermion mixtures of ultra-cold atoms in optical lattices. We used the method based on the Hubbard operator approach for an on-site basis. The equation for fermion Green's function in the Bose-Fermi-Hubbard model is built; Green's functions of higher orders are decoupled in the Hubbard-I approximation (the case of the strong on-site interaction). The corresponding spectral densities are calculated. In the case of hard-core bosons, the condition of appearance of additional bands in the fermion spectrum is investigated. It is shown that these bands exist only in the state with a Bose- Einstein condensate and appear because of the mixing of states with different numbers of bosons. These additional bands can be interpreted as a manifestation of composite excitations (when the appearance of a fermion on the site is accompanied by the simultaneous creation (or annihilation) of a boson)
Galactic cold dark matter as a Bose-Einstein condensate of WISPs
Energy Technology Data Exchange (ETDEWEB)
Pires, M.O.C.; Souza, J.C.C. de, E-mail: marcelo.pires@ufabc.edu.br, E-mail: jose.souza@ufabc.edu.br [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia 166, 09210-170, Santo André, SP (Brazil)
2012-11-01
We propose here the dark matter content of galaxies as a cold bosonic fluid composed of Weakly Interacting Slim Particles (WISPs), represented by spin-0 axion-like particles and spin-1 hidden bosons, thermalized in the Bose-Einstein condensation state and bounded by their self-gravitational potential. We analyze two zero-momentum configurations: the polar phases in which spin alignment of two neighbouring particles is anti-parallel and the ferromagnetic phases in which every particle spin is aligned in the same direction. Using the mean field approximation we derive the Gross-Pitaevskii equations for both cases, and, supposing the dark matter to be a polytropic fluid, we describe the particles density profile as Thomas-Fermi distributions characterized by the halo radii and in terms of the scattering lengths and mass of each particle. By comparing this model with data obtained from 42 spiral galaxies and 19 Low Surface Brightness (LSB) galaxies, we constrain the dark matter particle mass to the range 10{sup −6}–10{sup −4} eV and we find the lower bound for the scattering length to be of the order 10{sup −14} fm.
Quasi one-dimensional Bose-Einstein condensate in a gravito-optical surface trap
Akram, Javed; Girodias, Benjamin; Pelster, Axel
2016-04-01
We study both static and dynamic properties of a weakly interacting Bose-Einstein condensate (BEC) in a quasi one-dimensional gravito-optical surface trap, where the downward pull of gravity is compensated by the exponentially decaying potential of an evanescent wave. First, we work out approximate solutions of the Gross-Pitaevskii equation for both a small number of atoms using a Gaussian ansatz and a larger number of atoms using the Thomas-Fermi limit. Then we confirm the accuracy of these analytical solutions by comparing them to numerical results. From there, we numerically analyze how the BEC cloud expands non-ballistically, when the confining evanescent laser beam is shut off, showing agreement between our theoretical and previous experimental results. Furthermore, we analyze how the BEC cloud expands non-ballistically due to gravity after switching off the evanescent laser field in the presence of a hard-wall mirror which we model by using a blue-detuned far-off-resonant sheet of light. There we find that the BEC shows significant self-interference patterns for a large number of atoms, whereas for a small number of atoms, a revival of the BEC wave packet with few matter-wave interference patterns is observed.
Precise measurement of optical Feshbach resonance strengths in a Bose-Einstein Condensate of 174 Yb
Kim, Min-Seok; Lee, Jeongwon; Lee, Jae Hoon; Shin, Yong-Il; Mun, Jongchul; Seoul National University Collaboration; Korea Research Institute of Standard; Science Collaboration
2016-05-01
We measure the optical length, which characterizes the coupling strength of an optical Feshbach resonance, of four shallow molecular bound levels in 3Σu+ with a Bose-Einstein Condensate (BEC) of a 174 Yb. A photoassociation (PA) beam is applied red detuned from the 1 S0-3 P1 intercombination level to obtain highly resolved spectra of the molecular levels. Due to the narrow linewidth of the atomic resonance (Γ = 2 π × 182 kHz), the atom loss and heating of the BEC due to the PA photons can be acutely suppressed. The measured optical lengths per PA laser intensity of the least bound molecular vibrational levels ν' = -1, -2, -3 and -4, labeled from the resonance of the intercombination line, are 1 . 01 ×104 4a0 /(Wcm-2), 1 . 07 ×104 3a0 /(Wcm-2), 6 . 90 ×103 12a0 /(Wcm-2) and 3 . 67 ×103 ×104 6a0 /(Wcm-2), respectively. This result will help better understand the long-range interaction strength between bound ytterbium atoms.
Jiang, Zhang; Caves, Carlton M.
2016-03-01
We encode the many-body wave function of a Bose-Einstein condensate (BEC) in the N -particle sector of an extended catalytic state. This catalytic state is a coherent state for the condensate mode and an arbitrary state for the modes orthogonal to the condensate mode. Going to a time-dependent interaction picture where the state of the condensate mode is displaced to the vacuum, we can organize the effective Hamiltonian by powers of N-1 /2. Requiring the terms of order N1 /2 to vanish gives the Gross-Pitaevskii equation. Going to the next order, N0, we derive equations for the number-conserving Bogoliubov approximation, first given by Castin and Dum [Phys. Rev. A 57, 3008 (1998), 10.1103/PhysRevA.57.3008]. In contrast to other approaches, ours is well suited to calculating the state evolution in the Schrödinger picture; moreover, it is straightforward to generalize our method to multicomponent BECs and to higher-order corrections.
Directory of Open Access Journals (Sweden)
Gerardo Adesso
2013-05-01
Full Text Available We study a system represented by a Bose-Einstein condensate interacting with a cavity field in presence of a strong off-resonant pumping laser. This system can be described by a three-mode Gaussian state, where two are the atomic modes corresponding to atoms populating upper and lower momentum sidebands and the third mode describes the scattered cavity field light. We show that, as a consequence of the collective atomic recoil instability, these modes possess a genuine tripartite entanglement that increases unboundedly with the evolution time and is larger than the bipartite entanglement in any reduced two-mode bipartition. We further show that the state of the system exhibits genuine tripartite nonlocality, which can be revealed by a robust violation of the Svetlichny inequality when performing displaced parity measurements. Our exact results are obtained by exploiting the powerful machinery of phase-space informational measures for Gaussian states, which we briefly review in the opening sections of the paper.
Slowing and storing of photons in Bose-Einstein condensates: A microscopic theory
Juzeliunas, Gediminas; Carmichael, Howard J.
2001-05-01
Recently electromagnetically induced transparency (EIT) was shown to bring laser pulses to a complete stop by switching off the control pulse in atomic gases [1,2]. The phenomenon can be explained in terms of the stable excitations of the light and the matter (dark state polaritons) [3], the group velocity of which is proportional to the intensity of the control pulse. The theory [3] (as well as other theories on the EIT) is designed for the classical gas of atoms. Here we present a microscopic theory of EIT in atomic Bose-Einstein condensates. The relaxation of the polaritons through their interaction with phonons has been investigated. The dark-state polaritons appear to be almost decoupled from the phonons leading to a weak decoherence. 1. C. Liu, Z. Dutton, C.H. Behroozi and L.V. Hau, Nature 409, 490 (2001). 2 D. P. Phillips, A. Fleishhauer, A. Mair, R.L. Walsworth and M.D. Lukin, Phys. Rev. Lett. 86, 783 (2001). 3. M. Fleishhauer and M.D. Lukin, Phys. Rev. Lett. 84, 5094 (2000).
Rashba-type Spin-orbit Coupling in Bilayer Bose-Einstein Condensates
Su, S -W; Sun, Q; Wen, L; Liu, W -M; Ji, A -C; Ruseckas, J; Juzeliunas, G
2016-01-01
We explore a new way of producing the Rasba spin-orbit coupling (SOC) for ultracold atoms by using a two-component (spinor) atomic Bose-Einstein condensate (BEC) confined in a bilayer geometry. The SOC of the Rashba type is created if the atoms pick up a {\\pi} phase after completing a cyclic transition between four combined spin-layer states composed of two spin and two layer states. The cyclic coupling of the spin-layer states is carried out by combining an intralayer Raman coupling and an interlayer laser assisted tunneling. We theoretically determine the ground-state phases of the spin-orbit-coupled BEC for various strengths of the atom-atom interaction and the laser-assisted coupling. It is shown that the bilayer scheme provides a diverse ground-state phase diagram. In an intermediate range of the atom-light coupling two interlacing lattices of half- skyrmions and half-antiskyrmions are spontaneously created. In the strong-coupling regime, where the SOC of the Rashba-type is formed, the ground state repre...
Nonlinear synthetic gauge potentials and sonic horizons in Bose-Einstein condensates
Butera, Salvatore; Faccio, Daniele; Öhberg, Patrik
2016-01-01
Phonons in a Bose-Einstein condensate can be made to behave as if they propagate in curved spacetime by controlling the condensate flow speed. Seemingly disconnected to this, artificial gauge potentials can be induced in charge neutral atomic condensates by for instance coupling two atomic levels to a laser field. Here we connect these two worlds and show that synthetic interacting gauge fields, i.e., density-dependent gauge potentials, induce a non-trivial spacetime structure for the phonons. This allows for the creation of new spacetime geometries which depend not on the flow speed of the condensate but on an easily controlled transverse laser phase. Using this, we show how to create artificial black holes in a stationary condensate, we simulate charge in a Reissner-Nordstr\\"om black hole and induce cosmological horizons by creating de Sitter spacetimes. We then show how to combine this de Sitter spacetime with a black hole, which also opens up the possibility to study in experiments its quantum stability.
Photoassociation spectroscopy of 174 Yb Bose-Einstein Condensate using the 1 S03 P1 transition
Mun, Jongchul; Lee, Jeongwon; Lee, Jae Hoon; Kim, Min-Seok; Shin, Yong-Il
2016-05-01
We studied the photoassociation spectrum of 174 Yb Bose-Einstein condensate (BEC) using an optical Feshbach resonance near the intercombination transition (1 S0 -3 P1, 578 nm). The optical length lopt, which characterize the interaction strength of optical Feshbach resonances, of four least-bound molecular levels (ν' = - 1 ~ - 4) were precisely determined by measuring the two-body loss rate at various optical powers. We also found the parameter η =Γspon /Γmol , which characterizes the enhancement of molecular loss, to be > 1 as in the previous studies. Our BEC apparatus and experimental scheme are also introduced in this presentation. This work was supported by KRISS creative research initiative.
Sykes, Andrew G; Davis, Matthew J; Roberts, David C
2009-08-21
The existence of frictionless flow below a critical velocity for obstacles moving in a superfluid is well established in the context of the mean-field Gross-Pitaevskii theory. We calculate the next order correction due to quantum and thermal fluctuations and find a nonzero force acting on a delta-function impurity moving through a quasi-one-dimensional Bose-Einstein condensate at all subcritical velocities and at all temperatures. The force occurs due to an imbalance in the Doppler shifts of reflected quantum fluctuations from either side of the impurity. Our calculation is based on a consistent extension of Bogoliubov theory to second order in the interaction strength, and finds new analytical solutions to the Bogoliubov-de Gennes equations for a gray soliton. Our results raise questions regarding the quantum dynamics in the formation of persistent currents in superfluids.
Dynamics of a trapped Bose-Einstein condensate in the presence of a one-dimensional optical lattice
Cataliotti, F S; Ferlaino, F; Fort, C; Maddaloni, P; Inguscio, M
2003-01-01
We explore the dynamics of a Bose-Einstein condensate created in the combined potential of a far-detuned laser standing wave superimposed to a 3D harmonic magnetic potential. We report the investigation of low-lying collective modes showing that the macroscopic dynamics along the optical lattice is strongly modified, resulting in a shift of the dipole and quadrupole mode frequencies depending on the height of the optical lattice, whereas the transverse breathing mode, occurring perpendicularly to the lattice axis, is not perturbed. The experimental findings are compared with the theoretical treatment that generalizes the hydrodynamic equation of superfluids for a weakly interacting Bose gas to include the effects of the periodic potential. We show that the array of condensates trapped in the optical wells and driven by the harmonic magnetic potential is equivalent to an array of Josephson junctions. In the regime of 'small' amplitude dipole oscillation the system performs a collective motion and we investigat...
Bhowmik, Anal; Majumder, Sonjoy; Deb, Bimalendu
2016-01-01
The exchange of orbital angular momentum (OAM) between optical vortex and the center-of-mass (c.m.) motion of an atom or molecule is well known in paraxial approximation. We show here the possible superposition of vortex states with different angular momentum in condensed atoms in interaction with focused optical vortex field. Since, spin angular momentum (SAM) is coupled with OAM of the focused field, both angular momenta are now possible to be transferred to the internal electronic and external c.m. motion of atom provided both the motions are coupled. We study how two-photon Rabi frequencies of stimulated Raman transitions vary with focusing angles for different combinations of OAM and SAM of optical states. We demonstrate the possible generation of vortex-antivortex structure and discuss the interference of three vortex states in a single component Bose-Einstein condensate.
Liñán-García, Ernesto; Sánchez-Hernández, Juan Paulo; González-Barbosa, J. Javier; González-Flores, Carlos
2016-01-01
A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA. PMID:27413369
Bose-Einstein Kondensation: Når atomer synger i kor
DEFF Research Database (Denmark)
Nygaard, Nicolai
2005-01-01
manuskriptet til Einstein, som prompte oversatte det til tysk og sørgede for at det blev publiceret. Einstein udvidede efterfølgende Boses analyse til at omfatte massive partikler og opdagede herved det fænomen vi idag kender som Bose-Einstein kondensation. Udgivelsesdato: Marts...
Quantum Entanglement and Spin Squeezing of Two Species Bose-Einstein Condensates
Li, Song-Song
2016-09-01
We investigate quantum entanglement and spin squeezing of two species Bose-Einstein condensates. By the rotating-wave approximation, we obtain the effective Hamiltonian and the wave function of the system. It's shown that more entanglement and squeezing may be achieved by increasing the population difference of particles.
Dicke superradiance, Bose-Einstein condensation of photons and spontaneous symmetry breaking
Vyas, Vivek M; Srinivasan, V
2016-01-01
It is shown that the phenomenon of Dicke superradiance essentially occurs due to spontaneous symmetry breaking. Two generalised versions of the Dicke model are studied, and compared with a model that describes photonic Bose-Einstein condensate, which was experimentally realised. In all the models, it is seen that, the occurrence of spontaneous symmetry breaking is responsible for coherent radiation emission.
PHENIX results on L\\'evy analysis of Bose-Einstein correlation functions
Kincses, Dániel
2016-01-01
The nature of the quark-hadron phase transition can be investigated through analyzing the space-time structure of the hadron emission source. For this, the Bose-Einstein or HBT correlations of identified charged particles are among the best observables. In this paper we present the latest results from the RHIC PHENIX experiment on such measurements.
Frausto-Solis, Juan; Liñán-García, Ernesto; Sánchez-Hernández, Juan Paulo; González-Barbosa, J Javier; González-Flores, Carlos; Castilla-Valdez, Guadalupe
2016-01-01
A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA. PMID:27413369
Testing quantum superpositions of the gravitational field with Bose-Einstein condensates
Lindner, Netanel H.; Peres, Asher
2004-01-01
We consider the gravity field of a Bose-Einstein condensate in a quantum superposition. The gravity field then is also in a quantum superposition which is in principle observable. Hence we have ``quantum gravity'' far away from the so-called Planck scale.
Phase fluctuations and first-order correlation functions of dissipative Bose-Einstein condensates
De Leeuw, A. W.; Stoof, H. T C; Duine, R. A.
2014-01-01
We investigate the finite-lifetime effects on first-order correlation functions of dissipative Bose-Einstein condensates. By taking into account the phase fluctuations up to all orders, we show that the finite-lifetime effects are negligible for the spatial first-order correlation functions, but hav
Synthesize Neutron-Drip-Line-Nuclides with Free-Neutron Bose-Einstein Condensates Experimentally
Dong, Bao-Guo
2014-01-01
We first show a possible way to create a new type of matter, free-neutron Bose-Einstein condensate by the ultracold free-neutron-pair Bose-Einstein condensation and then determine the neutron drip line experimentally. The Bose-Einstein condensation of bosonic and fermionic atoms in atomic gases was performed experimentally and predicted theoretically early. Neutrons are similar to fermionic atoms. We found free neutrons could be cooled to ultracold neutrons with very low energy by other colder neutral atoms which are cooled by the laser. These neutrons form neutron pairs with spin zero, and then ultracold neutron-pairs form Bose-Einstein condensate. Our results demonstrate how these condensates can react with accelerated ion beams at different energy to synthesize very neutron-rich nuclides near, on or/and beyond the neutron drip line, to determine the neutron drip line and whether there are long-life nuclide or isomer islands beyond the neutron drip line experimentally. Otherwise, these experimental results ...
Effect of residual Bose-Einstein correlations on the Dalitz plot of hadronic charm meson decay
Cuautle, E
1998-01-01
We show that the presence of residual Bose-Einstein correlations may affect the resonant contribution of hadronic charm decays where two identical pions appear in the final state. The distortion of the phase space of the reaction would be visible in the dalitz plot. The decay D+ --> K- pi+ pi+ is discussed but results can be generalized to any decay with identical bosons.
Exact periodic wave and soliton solutions in two-component Bose-Einstein condensates
Institute of Scientific and Technical Information of China (English)
Li Hua-Mei
2007-01-01
We present several families of exact solutions to a system of coupled nonlinear Schr(o)dinger equations. The model describes a binary mixture of two Bose-Einstein condensates in a magnetic trap potential. Using a mapping deformation method, we find exact periodic wave and soliton solutions, including bright and dark soliton pairs.
Bose-Einstein condensation in a tightly confining dc magnetic trap
M.O. Mewes; M.R. Andrews; N.J. van Druten; D.M. Kurn; D.S. Durfee; W. Ketterle
1996-01-01
Bose-Einstein condensation of sodium atoms has been observed in a novel "cloverleaf" trap. This trap combines tight confinement with excellent optical access, using only dc electromagnets. Evaporative cooling in this trap produced condensates of 5 x 10/6 atoms, a tenfold improvement over previous re
't Hooft-Polyakov monopoles in an antiferromagnetic Bose-Einstein condensate
Stoof, H.T.C.; Vliegen, E.; Al Khawaja, U.
2001-01-01
We show that an antiferromagnetic spin-1 Bose-Einstein condensate, which can for instance be created with 23-Na atoms in an optical trap, has not only singular line-like vortex excitations, but also allows for singular point-like topological excitations, i.e., 't Hooft-Polyakov monopoles. We discuss the static and dynamic properties of these monopoles.
Vortex Nucleation and Array Formation in a Rotating Bose-Einstein Condensate
Tsubota, Makoto; Kasamatsu, Kenichi; Ueda, Masahito
2001-01-01
We study the dynamics of vortex lattice formation of a rotating trapped Bose-Einstein condensate by numerically solving the two-dimensional Gross-Pitaevskii equation, and find that the condensate undergoes elliptic deformation, followed by unstable surface-mode excitations before forming a quantized vortex lattice. The dependence of the number of vortices on the rotation frequency is obtained.
Acceleration of quasi-particle modes in Bose-Einstein condensates
Marzlin, Karl-Peter; Zhang, Weiping
1998-01-01
We analytically examine the dynamics of quasi-particle modes occuring in a Bose-Einstein condensate which is subject to a weak acceleration. It is shown that the momentum of a quasi-particle mode is squeezed rather than accelerated.
Interferometric detection of a single vortex in a dilute Bose-Einstein condensate
Chevy, F; Madison, K. W.; Bretin, V.; Dalibard, J.
2001-01-01
Using two radio frequency pulses separated in time we perform an amplitude division interference experiment on a rubidium Bose-Einstein condensate. The presence of a quantized vortex, which is nucleated by stirring the condensate with a laser beam, is revealed by a dislocation in the fringe pattern.
Ramsey fringes in a Bose-Einstein condensate between atoms and molecules
Kokkelmans, SJJMF Servaas; Holland, MJ
2002-01-01
In a recent experiment, a Feshbach scattering resonance was exploited to observe Ramsey fringes in a $^{85}$Rb Bose-Einstein condensate. The oscillation frequency corresponded to the binding energy of the molecular state. We show that the observations are remarkably consistent with predictions of a resonance field theory in which the fringes arise from oscillations between atoms and molecules.
How to create Alice string (half-quantum vortex) in a vector Bose-Einstein condensate
Leonhardt, U.; Volovik, G. E.
2000-01-01
We suggest a procedure how to prepare the vortex with N=1/2 winding number -- the counterpart of the Alice string -- in a Bose--Einstein condensate with hyperfine spin F=1. Other possible vortices in Bose-condensates are also discussed.
Maximal length of trapped one-dimensional Bose-Einstein condensates
Fischer, Uwe R.
2004-01-01
I discuss a Bogoliubov inequality for obtaining a rigorous bound on the maximal axial extension of inhomogeneous one-dimensional Bose-Einstein condensates. An explicit upper limit for the aspect ratio of a strongly elongated, harmonically trapped Thomas-Fermi condensate is derived.
Single-beam measurement of bose-einstein fluctuations in a natural gaussian radiation field
Alkemade, C.T.J.; Bolwijn, P.T.; Veer, J.H.C. van der
1966-01-01
Excess noise caused by Bose-Einstein fluctuations in the radiation from the anode of a carbon-arc was detected in the photo current of a cooled InSb photodiode. Its dependence on several parameters was found to agree with our theory.
Effect of atomic transfer on the decay of a Bose-Einstein condensate
Zin, P; Charzynski, S; Herschbach, N; Tol, P; Hogervorst, W; Vassen, W; Zin, Pawel; Dragan, Andrzej; Charzynski, Szymon; Herschbach, Norbert; Tol, Paul; Hogervorst, Wim; Vassen, Wim
2003-01-01
We present a model describing the decay of a Bose-Einstein condensate, which assumes the system to remain in thermal equilibrium during the decay. We show that under this assumption transfer of atoms occurs from the condensate to the thermal cloud enhancing the condensate decay rate.
THE GROWTH RATE AND STATISTICAL FLUCTUATION OF BOSE-EINSTEIN CONDENSATE FORMATION
Institute of Scientific and Technical Information of China (English)
Yan Ke-zhu; Tan Wei-han
2000-01-01
Using the generating function method to solve the master equation ofBose-Einstein condensate and to evaluate the growth rate, statisticalfluctuation of condensate atoms, we find out that there is a plateau inthe growth rate curve and a super-Poisson distribution observed.
Collision induced splitting of bright soliton in Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
Wang Yue-Yue; Zhang Jie-Fang
2009-01-01
This paper studies the collision dynamics of bright soliton in Bose-Einstein condensate with trapezoid potential. It is found that besides the total reflection and total transmission, one bright soliton can be divided into two bright solitons with different amplitudes in a controllable manner.
Frausto-Solis, Juan; Liñán-García, Ernesto; Sánchez-Hernández, Juan Paulo; González-Barbosa, J Javier; González-Flores, Carlos; Castilla-Valdez, Guadalupe
2016-01-01
A new hybrid Multiphase Simulated Annealing Algorithm using Boltzmann and Bose-Einstein distributions (MPSABBE) is proposed. MPSABBE was designed for solving the Protein Folding Problem (PFP) instances. This new approach has four phases: (i) Multiquenching Phase (MQP), (ii) Boltzmann Annealing Phase (BAP), (iii) Bose-Einstein Annealing Phase (BEAP), and (iv) Dynamical Equilibrium Phase (DEP). BAP and BEAP are simulated annealing searching procedures based on Boltzmann and Bose-Einstein distributions, respectively. DEP is also a simulated annealing search procedure, which is applied at the final temperature of the fourth phase, which can be seen as a second Bose-Einstein phase. MQP is a search process that ranges from extremely high to high temperatures, applying a very fast cooling process, and is not very restrictive to accept new solutions. However, BAP and BEAP range from high to low and from low to very low temperatures, respectively. They are more restrictive for accepting new solutions. DEP uses a particular heuristic to detect the stochastic equilibrium by applying a least squares method during its execution. MPSABBE parameters are tuned with an analytical method, which considers the maximal and minimal deterioration of problem instances. MPSABBE was tested with several instances of PFP, showing that the use of both distributions is better than using only the Boltzmann distribution on the classical SA.
On the occurrence and detectability of Bose-Einstein condensation in helium white dwarfs
International Nuclear Information System (INIS)
It has been recently proposed that helium white dwarfs may provide promising conditions for the occurrence of the Bose-Einstein condensation. The argument supporting this expectation is that in some conditions attained in the core of these objects, the typical De Broglie wavelength associated with helium nuclei is of the order of the mean distance between neighboring nuclei. In these conditions the system should depart from classical behavior showing quantum effects. As helium nuclei are bosons, they are expected to condense. In order to explore the possibility of detecting the Bose-Einstein condensation in the evolution of helium white dwarfs we have computed a set of models for a variety of stellar masses and values of the condensation temperature. We do not perform a detailed treatment of the condensation process but mimic it by suppressing the nuclei contribution to the equation of state by applying an adequate function. As the cooling of white dwarfs depends on average properties of the whole stellar interior, this procedure should be suitable for exploring the departure of the cooling process from that predicted by the standard treatment. We find that the Bose-Einstein condensation has noticeable, but not dramatic effects on the cooling process only for the most massive white dwarfs compatible with a helium dominated interior ( ≈ 0.50Msun) and very low luminosities (say, Log(L/Lsun) < −4.0). These facts lead us to conclude that it seems extremely difficult to find observable signals of the Bose-Einstein condensation. Recently, it has been suggested that the population of helium white dwarfs detected in the globular cluster NGC 6397 is a good candidate for detecting signals of the Bose-Einstein condensation. We find that these stars have masses too low and are too bright to have an already condensed interior
Su, Chuan-Qi; Gao, Yi-Tian; Wang, Qi-Min; Yang, Jin-Wei; Zuo, Da-Wei
2016-04-01
Under investigation in this paper is a variable-coefficient Gross-Pitaevskii equation which describes the Bose-Einstein condensate. Lax pair, bilinear forms and bilinear Bäcklund transformation for the equation under some integrable conditions are derived. Based on the Lax pair and bilinear forms, double Wronskian solutions are constructed and verified. The Nth-order nonautonomous solitons in terms of the double Wronskian determinant are given. Propagation and interaction for the first- and second-order nonautonomous solitons are discussed from three cases. Amplitudes of the first- and second-order nonautonomous solitons are affected by a real parameter related to the variable coefficients, but independent of the gain-or-loss coefficient m0(t) and linear external potential coefficient m1(t). For Case 1 [m0(t) = 0], m1(t) leads to the accelerated propagation of nonautonomous solitons. Parabolic-, cubic-, exponential- and cosine-type nonautonomous solitons are exhibited due to the different choices of m1(t). For Case 2 [m1(t) = 0], if the real part of the spectral parameter equals 0, stationary soliton can be formed. If we take the harmonic external potential coefficient m2(t) as a positive constant and let the real parts of the two spectral parameters be the same, bound-state-like structures can be formed, but there are only one attractive and two repulsive procedures. For Case 3 [m0(t) and m1(t) are taken as nonzero constants], head-on interaction, overtaking interaction and bound-state structure can be formed based on the signs of the two spectral parameters.
International Nuclear Information System (INIS)
We show that the galactic dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate [6] trapped by a self-graviting potential [5], may be stable in the Thomas-Fermi approximation since appropriate choices for the dark matter particle mass and scattering length are made. The demonstration is performed by means of the calculation of the potential, kinetic and self-interaction energy terms of a galactic halo described by a Boehmer-Harko density profile. We discuss the validity of the Thomas-Fermi approximation for the halo system, and show that the kinetic energy contribution is indeed negligible
Energy Technology Data Exchange (ETDEWEB)
De Souza, J.C.C.; Pires, M.O.C., E-mail: jose.souza@ufabc.edu.br, E-mail: marcelo.pires@ufabc.edu.br [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adélia 166, Santo André, SP, 09210-170 (Brazil)
2014-03-01
We show that the galactic dark matter halo, considered composed of an axionlike particles Bose-Einstein condensate [6] trapped by a self-graviting potential [5], may be stable in the Thomas-Fermi approximation since appropriate choices for the dark matter particle mass and scattering length are made. The demonstration is performed by means of the calculation of the potential, kinetic and self-interaction energy terms of a galactic halo described by a Boehmer-Harko density profile. We discuss the validity of the Thomas-Fermi approximation for the halo system, and show that the kinetic energy contribution is indeed negligible.
Perceived Attractiveness and Classroom Interactions
Algozzine, Bob
1977-01-01
Adams and Cohen (1974) demonstrated that facial attractiveness was a salient factor in differential student-teacher interactions. This research investigates further the interaction between teachers and children perceived to be attractive or unattractive by those teachers. It was hypothesized that attractive children would exhibit more "positive,"…
Cosmological Constraints on Bose-Einstein-Condensed Scalar Field Dark Matter
Li, B.; Rindler-Daller, T.; Shapiro, P. R.
2013-10-01
We focus on the hypothesis that the darkmatter is comprised of ultralight bosons that form a Bose-Einstein Condensate (BEC), described by a complex scalar field. We calculate the evolution of the Friedmann-Robertson-Walker (FRW) universe in the presence of the BEC scalar field dark matter (SFDM).We find that, while WIMP CDM is non-relativistic at all times after it decouples, the equation of state of SFDM is found to be relativistic at early times, evolving from stiff (p¯ =r¯ ) to radiation-like (p¯ =r¯/3), before it becomes non-relativistic and CDM-like at late times (p¯ = 0. The stiff phase is a distinctive feature of our model. The timing of the transitions between these phases and regimes is shown to yield fundamental constraints on the SFDM model parameters, particle mass m and self-interaction coupling strength l . We show that SFDM is compatible with observations of the evolving background universe, by deriving the range of particle parameters required to match observations of the cosmic microwave background (CMB) and the abundances of the light elements produced by Big Bang nucleosynthesis (BBN), including Neff, the effective number of neutrino species, and the epoch of matter-radiation equality zeq. This yields m ≥ 2.4× 10-21eV/c2 and 9.5×10-19eV-1cm3 ≤l /(mc2)2 ≤ 4×10-17eV-1cm3. Indeed, our model can accommodate current observations in which Neff is higher at the BBN epoch than at zeq, probed by the CMB, which is otherwise unexplained by the standard CDM model involving WIMPs.
International Nuclear Information System (INIS)
For the derivation of the dilute Bose-Einstein condensate density and its phase, we have developed the perturbative approach for the solution of the stationary state couple Gross-Pitaevskii hydrodynamic equations. The external disorder potential is considered as small parameter in this approach. We have derived expressions for the total density, condensate density, condensate density depletion and superfluid velocity of the one-dimensional Bose-Einstein condensate for the disorder potential, which has a general form. (authors)
Abdullaev, D. B.; Abdullaev, B.; Musakhanov, M. M.
2015-01-01
For the derivation of the dilute Bose-Einstein condensate density and its phase, we have developed the perturbative approach for the solution of the stationary state couple Gross-Pitaevskii hydrodynamic equations. The external disorder potential is considered as a small parameter in this approach. We have derived expressions for the total density, condensate density, condensate density depletion and superfluid velocity of the Bose-Einstein condensate in an infinite length ring with disorder p...
Developing density functional theory for Bose-Einstein condensates. The case of chemical bonding
International Nuclear Information System (INIS)
Since the nowadays growing interest in Bose-Einstein condensates due to the expanded experimental evidence on various atomic systems within optical lattices in weak and strong coupling regimes, the connection with Density Functional Theory is firstly advanced within the mean field framework at three levels of comprehension: the many-body normalization condition, Thomas-Fermi limit, and the chemical hardness closure with the inter-bosonic strength and universal Hohenberg-Kohn functional. As an application the traditional Heitler-London quantum mechanical description of the chemical bonding for homopolar atomic systems is reloaded within the non-linear Schrödinger (Gross-Pitaevsky) Hamiltonian; the results show that a two-fold energetic solution is registered either for bonding and antibonding states, with the bosonic contribution being driven by the square of the order parameter for the Bose-Einstein condensate density in free (gas) motion, while the associate wave functions remain as in classical molecular orbital model
Bose-Einstein correlations in one and two dimensions in deep inelastic scattering
Abramowicz, H; Adamus, M; Adler, V; Aghuzumtsyan, G; Antonioli, P; Antonov, A; Arneodo, M; Bailey, D S; Bamberger, A; Barakbaev, A N; Barbagli, G; Barbi, M; Bari, G; Barreiro, F; Bartsch, D; Basile, M; Behrens, U; Bell, M; Bellagamba, L; Benen, A; Bertolin, A; Bhadra, S; Bloch, I; Bodmann, B; Bold, T; Boos, E G; Borras, K; Boscherini, D; Brock, I; Brook, N H; Brugnera, R; Brümmer, N; Bruni, A; Bruni, G; Bussey, P J; Butterworth, J M; Bylsma, B; Caldwell, A; Capua, M; Cara Romeo, G; Carli, T; Carlin, R; Catterall, C D; Chekanov, S; Chiochia, V; Chwastowski, J; Ciborowski, J; Ciesielski, R; Cifarelli, Luisa; Cindolo, F; Cloth, P; Cole, J E; Collins-Tooth, C; Contin, A; Cooper-Sarkar, A M; Coppola, N; Cormack, C; Corradi, M; Corriveau, F; Cottrell, A; D'Agostini, G; Dal Corso, F; Danilov, P; Dannheim, D; De Pasquale, S; Dementiev, R K; Derrick, M; Deshpande, Abhay A; Devenish, R C E; Dhawan, S; Dolgoshein, B A; Doyle, A T; Drews, G; Durkin, L S; Dusini, S; Eisenberg, Y; Ermolov, P F; Eskreys, Andrzej; Ferrando, J; Ferrero, M I; Figiel, J; Filges, D; Foster, B; Foudas, C; Fourletov, S; Fourletova, J; Fricke, U; Fusayasu, T; Gabareen, A; Galas, A; Gallo, E; Garfagnini, A; Geiser, A; Genta, C; Gialas, I; Giusti, P; Gladilin, L K; Gladkov, D; Glasman, C; Gliga, S; Goers, S; Golubkov, Yu A; Goncalo, R; González, O; Göttlicher, P; Grabowska-Bold, I; Grijpink, S; Grzelak, G; Gutsche, O; Gwenlan, C; Haas, T; Hain, W; Hall-Wilton, R; Hamatsu, R; Hamilton, J; Hanlon, S; Hart, J C; Hartmann, H; Hartner, G; Heaphy, E A; Heath, G P; Helbich, M; Heusch, C A; Hilger, E; Hillert, S; Hirose, T; Hochman, D; Holm, U; Iacobucci, G; Iga, Y; Inuzuka, M; Irrgang, P; Jakob, P; Jones, T W; Kagawa, S; Kahle, B; Kaji, H; Kananov, S; Kataoka, M; Katkov, I I; Kcira, D; Khein, L A; Kim, J Y; Kim, Y K; Kind, O; Kisielewska, D; Kitamura, S; Klimek, K; Koffeman, E; Kohno, T; Kooijman, P; Koop, T; Korzhav, I A; Kotanski, A; Kötz, U; Kowal, A M; Kowal, M; Kowalski, H; Kowalski, T; Krakauer, D; Kramberger, G; Kreisel, A; Krumnack, N; Kuze, M; Kuzmin, V A; Labarga, L; Labes, H; Lainesse, J; Lammers, S; Lee, J H; Lelas, D; Levchenko, B B; Levman, G M; Levy, A; Li, L; Lightwood, M S; Lim, H; Lim, I T; Limentani, S; Ling, T Y; Liu, X; Löhr, B; Lohrmann, E; Loizides, J H; Long, K R; Longhin, A; Lukina, O Yu; Luzniak, P; Maddox, E; Magill, S; Mankel, R; Margotti, A; Marini, G; Martin, J F; Mastroberardino, A; Matsuzawa, K; Mattingly, M C K; McCubbin, N A; Mellado, B; Melzer-Pellmann, I A; Menary, S R; Metlica, F; Meyer, U; Miglioranzi, S; Milite, M; Mirea, A; Monaco, V; Montanari, A; Mus, B; Nagano, K; Namsoo, T; Nania, R; Nguyen, C N; Nigro, A; Ning, Y; Notz, D; Nowak, R J; Nuncio-Quiroz, A E; Oh, B Y; Olkiewicz, K; Pac, M Y; Padhi, S; Paganis, S; Palmonari, F; Parenti, A; Park, I H; Patel, S; Paul, E; Pavel, N; Pawlak, J M; Pelfer, P G; Pellegrino, A; Pesci, A; Piotrzkowski, K; Plucinsky, P P; Pokrovskiy, N S; Polini, A; Posocco, M; Proskuryakov, A S; Przybycien, M B; Rautenberg, J; Raval, A; Reeder, D D; Ren, Z; Renner, R; Repond, J; Riveline, U; Karshon, M; Robins, S; Rosin, M; Rurua, L; Ruspa, M; Sacchi, R; Salehi, H; Sartorelli, G; Savin, A A; Saxon, D H; Schagen, S; Schioppa, M; Schlenstedt, S; Schleper, P; Schmidke, W B; Schneekloth, U; Sciulli, F; Shcheglova, L M; Skillicorn, I O; Slominski, W; Smith, W H; Soares, M; Solano, A; Son, D; Sosnovtsev, V V; Stairs, D G; Stanco, L; Standage, J; Stifutkin, A; Stoesslein, U; Stonjek, S; Stopa, P; Straub, P B; Suchkov, S; Susinno, G; Suszycki, L; Sutton, M R; Sztuk, J; Szuba, D; Szuba, J; Tandler, J; Tapper, A D; Targett, C; Tassi, E; Tawara, T; Terron, J; Tiecke, H G; Tokushuku, K; Tsurugai, T; Turcato, M; Tymieniecka, T; Ukleja, A; Ukleja, J; Vázquez, M; Velthuis, J J; Vlasov, N N; Voss, K C; Walczak, R; Walsh, R; Wang, M; Weber, A; Whitmore, J J; Wick, K; Wiggers, L; Will, H H; Wing, M; Wolf, G; Yamada, S; Yamashita, T; Yamazaki, Y; Yoshida, R; Youngman, C; Zambrana, M; Zawiejski, L; Zeuner, W; Zhautykov, B O; Zichichi, A; Ziegler, A; Zotkin, S A; De Wolf, E; Del Peso, J
2003-01-01
Bose-Einstein correlations in one and two dimensions have been studied in deep inelastic EP scattering events measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb-1. The correlations are independent of the virtuality of the exchanged photon, Q2, in the range 0.1100 GeV2. The two-dimensional shape of the particle-production source was investigated, and a significant difference between the transverse and the longitudinal dimensions of the source is observed.This difference also shows no Q2 dependence.The results demonstrate that Bose-Einstein interference, and hence the size of the particle-production source, is insensitive to the hard subprocess.
Atomic Tunneling Effect in Two-Component Bose-Einstein Condensates with a Coupling Drive
Institute of Scientific and Technical Information of China (English)
JIAO Zhi-Yong; YU Zhao-Xian; YANG Xin-Jian
2004-01-01
In this paper, we have studied the atomic population difference and the atomic tunneling current of twocomponent Bose-Einstein condensates with a coupling drive. It is found that when the two-component Bose-Einstein condensates are initially in the coherent states, the atomic population difference may exhibit the step structure, in which the numbers of the step increase with the decrease of the Rabi frequency and with the increment of the initial phase difference. The atomic population difference may exhibit collapses, and revivals, in which their periods are affected dramatically by the Rabi frequency and the initial phase difference. The atomic tunneling current may exhibit damping oscillation behaviors, and exist the step structure for the time range of 10-10 ～ 10-9 second.
Atomic Tunneling Effect in Two-Component Bose-Einstein Condensates with a Coupling Drive
Institute of Scientific and Technical Information of China (English)
JIAOZhi-Yong; YUZhao-Xian; YANGXin-Jian
2004-01-01
In this paper, we have studied the atomic population difference and the atomic tunneling current of two-component Bose-Einstein condensates with a coupling drive. It is found that when the two-component Bose Einstein condensates are initially in the coherent states, the atomic population difference may exhibit the step structure, in which the numbers of the step increase with the decrease of the Rabi frequency and with the increment of the initial phase difference. The atomic population difference may exhibit collapses, and revivals, in which their periods are affected dramatically by the Rabi frequency and the initial phase difference. The atomic tunneling current may exhibit damping oscillation behaviors, and exist the step structure for the time range of 10-10 ～ 10-9 second.
Dark matter as the Bose-Einstein condensation in loop quantum cosmology
Atazadeh, K.; Darabi, F.; Mousavi, M.
2016-06-01
We consider the FLRW universe in a loop quantum cosmological model filled with radiation, baryonic matter (with negligible pressure), dark energy, and dark matter. The dark matter sector is supposed to be of Bose-Einstein condensate type. The Bose-Einstein condensation process in a cosmological context by supposing it as an approximate first-order phase transition, has already been studied in the literature. Here, we study the evolution of the physical quantities related to the early universe description such as the energy density, temperature, and scale factor of the universe, before, during, and after the condensation process. We also consider in detail the evolution era of the universe in a mixed normal-condensate dark matter phase. The behavior and time evolution of the condensate dark matter fraction is also analyzed.
Developing density functional theory for Bose-Einstein condensates. The case of chemical bonding
Energy Technology Data Exchange (ETDEWEB)
Putz, Mihai V., E-mail: mvputz@cbg.uvt.ro [Laboratory of Physical and Computational Chemistry, Chemistry Department, West University of Timisoara, Str. Pestalozzi No. 16, 300115 Timisoara, Romania and Theoretical Physics Institute, Free University Berlin, Arnimallee 14, 14195 Berlin (Germany)
2015-01-22
Since the nowadays growing interest in Bose-Einstein condensates due to the expanded experimental evidence on various atomic systems within optical lattices in weak and strong coupling regimes, the connection with Density Functional Theory is firstly advanced within the mean field framework at three levels of comprehension: the many-body normalization condition, Thomas-Fermi limit, and the chemical hardness closure with the inter-bosonic strength and universal Hohenberg-Kohn functional. As an application the traditional Heitler-London quantum mechanical description of the chemical bonding for homopolar atomic systems is reloaded within the non-linear Schrödinger (Gross-Pitaevsky) Hamiltonian; the results show that a two-fold energetic solution is registered either for bonding and antibonding states, with the bosonic contribution being driven by the square of the order parameter for the Bose-Einstein condensate density in free (gas) motion, while the associate wave functions remain as in classical molecular orbital model.
Coexistence of photonic and atomic Bose-Einstein condensates in ideal atomic gases
Directory of Open Access Journals (Sweden)
N. Boichenko
2015-12-01
Full Text Available We have studied conditions of photon Bose-Einstein condensate formation that is in thermodynamic equilibrium with ideal gas of two-level Bose atoms below the degeneracy temperature. Equations describing thermodynamic equilibrium in the system were formulated; critical temperatures and densities of photonic and atomic gas subsystems were obtained analytically. Coexistence conditions of these photonic and atomic Bose-Einstein condensates were found. There was predicted the possibility of an abrupt type of photon condensation in the presence of Bose condensate of ground-state atoms: it was shown that the slightest decrease of the temperature could cause a significant gathering of photons in the condensate. This case could be treated as a simple model of the situation known as "stopped light" in cold atomic gas. We also showed how population inversion of atomic levels can be created by lowering the temperature. The latter situation looks promising for light accumulation in atomic vapor at very low temperatures.
Spin-momentum coupled Bose-Einstein condensates with lattice band pseudospins.
Khamehchi, M A; Qu, Chunlei; Mossman, M E; Zhang, Chuanwei; Engels, P
2016-01-01
The quantum emulation of spin-momentum coupling, a crucial ingredient for the emergence of topological phases, is currently drawing considerable interest. In previous quantum gas experiments, typically two atomic hyperfine states were chosen as pseudospins. Here, we report the observation of a spin-momentum coupling achieved by loading a Bose-Einstein condensate into periodically driven optical lattices. The s and p bands of a static lattice, which act as pseudospins, are coupled through an additional moving lattice that induces a momentum-dependent coupling between the two pseudospins, resulting in s-p hybrid Floquet-Bloch bands. We investigate the band structures by measuring the quasimomentum of the Bose-Einstein condensate for different velocities and strengths of the moving lattice, and compare our measurements to theoretical predictions. The realization of spin-momentum coupling with lattice bands as pseudospins paves the way for engineering novel quantum matter using hybrid orbital bands. PMID:26924575
Dark matter as the Bose-Einstein condensation in loop quantum cosmology
Energy Technology Data Exchange (ETDEWEB)
Atazadeh, K.; Mousavi, M. [Azarbaijan Shahid Madani University, Department of Physics, Tabriz (Iran, Islamic Republic of); Darabi, F. [Azarbaijan Shahid Madani University, Department of Physics, Tabriz (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha (RIAAM), Maragha (Iran, Islamic Republic of)
2016-06-15
We consider the FLRW universe in a loop quantum cosmological model filled with radiation, baryonic matter (with negligible pressure), dark energy, and dark matter. The dark matter sector is supposed to be of Bose-Einstein condensate type. The Bose-Einstein condensation process in a cosmological context by supposing it as an approximate first-order phase transition, has already been studied in the literature. Here, we study the evolution of the physical quantities related to the early universe description such as the energy density, temperature, and scale factor of the universe, before, during, and after the condensation process. We also consider in detail the evolution era of the universe in a mixed normal-condensate dark matter phase. The behavior and time evolution of the condensate dark matter fraction is also analyzed. (orig.)
Lorentz-invariance violating effects in the Bose-Einstein condensation of an ideal bosonic gas
Casana, Rodolfo
2011-01-01
We have studied the effects of Lorentz-invariance violation in the Bose-Einstein condensation (BEC) of an ideal bosonic gas, assessing both the nonrelativistic and ultrarelativistic limits. Our model describes a massive complex scalar field coupled to a CPT-even and Lorentz-violating background. First, by starting from the nonrelativistic limit of our model and by using experimental data, we give upper limits for some parameters of our model. But, the existence of the nonrelativistic BEC, in a Lorentz-invariance violating (LIV) framework, imposes strong restrictions on some LIV parameters. It is shown that only the critical temperature gains LIV contributions. In the sequel, we analyze the ultrarelativistic Bose-Einstein condensation, constructing a well-defined partition function for the relativistic bosonic ideal gas, from which severe constraints on certain LIV parameters are imposed. The analysis of the ultrarelativistic BEC has shown that the critical temperature and the critical chemical potential are s...
Spin-momentum coupled Bose-Einstein condensates with lattice band pseudospins.
Khamehchi, M A; Qu, Chunlei; Mossman, M E; Zhang, Chuanwei; Engels, P
2016-01-01
The quantum emulation of spin-momentum coupling, a crucial ingredient for the emergence of topological phases, is currently drawing considerable interest. In previous quantum gas experiments, typically two atomic hyperfine states were chosen as pseudospins. Here, we report the observation of a spin-momentum coupling achieved by loading a Bose-Einstein condensate into periodically driven optical lattices. The s and p bands of a static lattice, which act as pseudospins, are coupled through an additional moving lattice that induces a momentum-dependent coupling between the two pseudospins, resulting in s-p hybrid Floquet-Bloch bands. We investigate the band structures by measuring the quasimomentum of the Bose-Einstein condensate for different velocities and strengths of the moving lattice, and compare our measurements to theoretical predictions. The realization of spin-momentum coupling with lattice bands as pseudospins paves the way for engineering novel quantum matter using hybrid orbital bands.
Critical temperature and condensed fraction of Bose-Einstein condensation in optical lattices
Institute of Scientific and Technical Information of China (English)
2007-01-01
Critical temperature and condensate fraction of Bose-Einstein condensation in the optical lattice are studied. The results show that the critical temperature in optical lattices can be characterized with an equivalent critical temperature in a single lattice, which provide a fast evaluation of critical temperature and condensate fraction of Bose-Einstein condensation confined with pure optical trap. Critical temperature can be estimated with an equivalent critical temperature. It is predicted that critical temperature is proportional to q in q number lattices for superfluid state and should be equal to that in a single lattic for Mott insulate state. Required potential depth or Rabi frequency and maximum atom number in the lattices both for superfluid state and Mott state are presented based on views of thermal mechanical statistics.
Sonic analog of gravitational black holes in Bose-Einstein condensates
Garay, Luis Javier; Anglin, J. R.; Cirac, J. I.; Zoller, P.
2000-01-01
It is shown that, in dilute-gas Bose-Einstein condensates, there exist both dynamically stable and unstable configurations which, in the hydrodynamic limit, exhibit a behavior resembling that of gravitational black holes. The dynamical instabilities involve creation of quasiparticle pairs in positive and negative energy states, as in the well-known suggested mechanism for black-hole evaporation. We propose a scheme to generate a stable sonic black hole in a ring trap.