Bose-Einstein Condensation of Atomic Hydrogen
Fried, Dale G.
1999-01-01
This thesis describes the observation and study of Bose-Einstein condensation of a trapped, dilute gas of atomic hydrogen. The condensate and normal gas are studied by two-photon spectroscopy of the 1S-2S transition. We condense over 10^9 atoms per second for several seconds, and the peak condensate density is around 5x10^15 cm^-3. Topics covered in the thesis include a theoretical analysis of Bose-condensed hydrogen, a description of the cryogenic trapping cell and the evaporative cooling te...
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.
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
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.)
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.
Coherently Scattering Atoms from an Excited Bose-Einstein Condensate
Bijlsma, M.J.; Stoof, H.T.C.
1999-01-01
We consider scattering atoms from a fully Bose-Einstein condensed gas. If we take these atoms to be identical to those in the Bose-Einstein condensate, this scattering process is to a large extent analogous to Andreev reflection from the interface between a superconducting and a normal metal. We determine the scattering wave function in both the absence and the presence of a vortex. Our results show a qualitative difference between these two cases that can be understood as due to an Aharonov-...
Production of a Bose Einstein condensate of metastable helium atoms
Santos, F. Pereira Dos; Léonard, J.; Wang, Junmin; Barrelet, C. J.; Perales, F.; Rasel, E.; Unnikrishnan, C. S.; Leduc, M.; Cohen-Tannoudji, C.
2003-04-01
We recently observed a Bose-Einstein condensate in a dilute gas of 4He in the 23S1 metastable state. In this article, we describe the successive experimental steps which led to the Bose-Einstein transition at 4.7 μK: loading of a large number of atoms in a MOT, efficient transfer into a magnetic Ioffé-Pritchard trap, and optimization of the evaporative cooling ramp. Quantitative measurements are also given for the rates of elastic and inelastic collisions, both above and below the transition.
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...
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 ...
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)
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 ...
A general approach to the Bose-einstein condensation of neutral atoms with repellent interaction
International Nuclear Information System (INIS)
A general approach to the Bose-Einstein condensation of neutral atoms with repellent interaction is presented. Especially in the case of free atoms (V = 0) with repellent interaction, an exact solution for the atom's wave function can be derived, and therefore the calculation of atom's Bose-Einstein condensation is completed
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.
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.
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
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
Dynamical tunneling with Bose-Einstein condensates on atom chips
International Nuclear Information System (INIS)
Full text: A generic feature of conservative classical dynamical systems with two or more degrees of freedom is that their trajectories form complicated phase space structures where chaos and regular motion are closely intertwined Among these structures are islands of regular motion that a classical system can not escape from but between which a quantum particle may tunnel. Dynamical tunneling of ultra cold atoms in standing wave has previously been observed but deep inside the quantum dynamical regime. Here we investigate the prospects for improved experiments with Bose Einstein condensates on atom chips that are closer to the classical regime In particular we concentrate on the effect of classical chaos on the tunnelling an issue of some controversy in the literature. Copyright (2005) Australian Institute of Physics
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.
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.
Cold Atoms and Bose-Einstein Condensates in Optical Dipole Potentials
Nes, Johanna
2008-01-01
In 1925, Einstein predicted the condensation of bosons into the ground state of the system for low (but finite) temperatures. Several phenomena, including superfluidity and superconductivity have been associated with Bose-Einstein condensation, but these systems interact strongly with their environment and pure Bose-Einstein condensation could not be established. It took 70 years, in which time the laser was discovered, and laser cooling techniques to manipulate atoms in a dilute atomic gas, ...
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.
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.
Quantized vortices in superfluid helium and atomic Bose-Einstein condensates
Tsubota, Makoto; Kasamatsu, Kenichi; Kobayashi, Michikazu
2010-01-01
This article reviews recent developments in the physics of quantized vortices in superfluid helium and atomic Bose-Einstein condensates. Quantized vortices appear in low-temperature quantum condensed systems as the direct product of Bose-Einstein condensation. Quantized vortices were first discovered in superfluid 4He in the 1950s, and have since been studied with a primary focus on the quantum hydrodynamics of this system. Since the discovery of superfluid 3He in 1972, quantized vortices cha...
Large atom number Bose-Einstein condensate of sodium
van der Stam, K M R; Meppelink, R; Vogels, J M; Van der Straten, P
2006-01-01
We describe the setup to create a large Bose-Einstein condensate containing more than 120x10^6 atoms. In the experiment a thermal beam is slowed by a Zeeman slower and captured in a dark-spot magneto-optical trap (MOT). A typical dark-spot MOT in our experiments contains 2.0x10^10 atoms with a temperature of 320 microK and a density of about 1.0x10^11 atoms/cm^3. The sample is spin polarized in a high magnetic field, before the atoms are loaded in the magnetic trap. Spin polarizing in a high magnetic field results in an increase in the transfer efficiency by a factor of 2 compared to experiments without spin polarizing. In the magnetic trap the cloud is cooled to degeneracy in 50 s by evaporative cooling. To suppress the 3-body losses at the end of the evaporation the magnetic trap is decompressed in the axial direction.
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...
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.
A permanent magnetic film atom chip for Bose-Einstein condensation
Hall, B. V.; Whitlock, S.; Scharnberg, F.; Hannaford, P; Sidorov, A.
2005-01-01
We present a hybrid atom chip which combines a permanent magnetic film with a micromachined current-carrying structure used to realize a Bose-Einstein condensate. A novel TbGdFeCo material with large perpendicular magnetization has been tailored to allow small scale, stable magnetic potentials for ultracold atoms. We are able to produce 87Rb Bose-Einstein condensates in a magnetic trap based on either the permanent magnetic film or the current-carrying structure. Using the condensate as a mag...
The effect of atomic transfer on the decay of a Bose-Einstein condensate
International Nuclear Information System (INIS)
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. (letter to the editor)
Effect of atomic transfer on the decay of a Bose-Einstein condensate
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.
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.
Quantum turbulence in trapped atomic Bose-Einstein condensates
Tsatsos, Marios C.; Tavares, Pedro E. S.; Cidrim, André; Fritsch, Amilson R.; Caracanhas, Mônica A.; dos Santos, F. Ednilson A.; Barenghi, Carlo F.; Bagnato, Vanderlei S.
2016-03-01
Turbulence, the complicated fluid behavior of nonlinear and statistical nature, arises in many physical systems across various disciplines, from tiny laboratory scales to geophysical and astrophysical ones. The notion of turbulence in the quantum world was conceived long ago by Onsager and Feynman, but the occurrence of turbulence in ultracold gases has been studied in the laboratory only very recently. Albeit new as a field, it already offers new paths and perspectives on the problem of turbulence. Herein we review the general properties of quantum gases at ultralow temperatures paying particular attention to vortices, their dynamics and turbulent behavior. We review the recent advances both from theory and experiment. We highlight, moreover, the difficulties of identifying and characterizing turbulence in gaseous Bose-Einstein condensates compared to ordinary turbulence and turbulence in superfluid liquid helium and spotlight future possible directions.
Vardi, A.; Moore, M. G.
2002-01-01
We study spontaneous directionality in the bosonic amplification of atom pairs emitted from an elongated Bose-Einstein condensate (BEC), an effect analogous to `superradiant' emission of atom-photon pairs. Using a simplified model, we make analytic predictions regarding directional effects for both atom-atom and atom-photon emission. These are confirmed by numerical mean-field simulations, demonstrating the the feasibility of nearly perfect directional emission along the condensate axis. The ...
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.
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.
Single-atom aided probe of the decoherence of a Bose-Einstein condensate
Ng, H. T.; Bose, S.
2008-01-01
We study a two-level atom coupled to a Bose-Einstein condensate. We show that the rules governing the decoherence of mesoscopic superpositions involving different classical-like states of the condensate can be probed using this system. This scheme is applicable irrespective of whether the condensate is initially in a coherent, thermal or more generally in any mixture of coherent states. The effects of atom loss and finite temperature to the decoherence can therefore be studied. We also discus...
Three-dimensional solitons in coupled atomic-molecular Bose-Einstein condensates
Vaughan, T. G.; Kheruntsyan, K. V.; Drummond, P. D.
2004-01-01
We present a theoretical analysis of three-dimensional (3D) matter-wave solitons and their stability properties in coupled atomic and molecular Bose-Einstein condensates (BEC). The soliton solutions to the mean-field equations are obtained in an approximate analytical form by means of a variational approach. We investigate soliton stability within the parameter space described by the atom-molecule conversion coupling, atom-atom s-wave scattering, and the bare formation energy of the molecular...
Bose-Einstein Condensate of Trimers Dressed by Atom-Dimer Cooper Pairs
Mackie, M; Dannenberg, O; Mackie, Matt; Piilo, Jyrki; Dannenberg, Olavi
2004-01-01
We theoretically examine the neutral atom-molecule analogue of the anomalous quantum correlations between degenerate electrons, i.e., Cooper pairs, that are responsible for superconductivity. Based on rogue dissociation of triatomic molecules (trimers) into opposite-momentum pairs of atoms and diatomic molecules (dimers) via a photoassociation or Feshbach resonance, we find a superfluid transition to a Bose-Einstein condensate of trimers dressed by atom-dimer Cooper pairs, at a critical temperature in reach of present ultracold technology.
A novel route to Bose-Einstein condensation of two-electron atoms
Halder, Purbasha; Yang, Chih-Yun; Hemmerich, Andreas
2012-01-01
We present a novel route to Bose-Einstein condensation devised for two-electron atoms, which do not admit practicable cooling techniques based upon narrow intercombination lines. A dipole trap for $^{40}$Ca atoms in the singlet ground state is loaded from a moderately cold source of metastable triplet atoms via spatially and energetically selective optical pumping permitting four orders of magnitude increase of the phase space density. Further cooling to quantum degeneracy is achieved by forc...
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.
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.
International Nuclear Information System (INIS)
The notion of Bose-Einstein condensation (BEC) is introduced in the simple case of a perfect gas of bosons. We show the existence of a singularity that was discovered by Einstein and that appears when the density in the phase space is above a critical value. A few years after the discovery of BEC in several gases, it is interesting to look back at some properties of superfluid helium, the author comments shortly on boiling and evaporation, then on the role of rotons and vortices in the existence of a critical velocity in superfluid helium. The author discusses also the existence of a condensate in a liquid with strong interactions and the pressure variation of its superfluid transition temperature. The discovery of BEC in dilute gases of Rb, Na and Li in magnetic traps has stimulated an enormous revival of the interest in macroscopic quantum behavior of dilute gas at low temperature. Experiments with trapped Bose condensed gases have revealed profound condensed matter behavior of these extremely dilute systems. The author describes the key features of this behavior and discusses theoretical approaches that are being used in the field of quantum gases. Methods of production and of detection of a BEC in gaseous phases are presented, the issue of the cooling of fermion gases and of Boson-fermions mixing is discussed. (A.C.)
Analogies between dark solitons in atomic Bose-Einstein condensates and optical systems
International Nuclear Information System (INIS)
Dark solitons have been observed in optical systems (optical fibres, dielectric guides and bulk media), and, more recently, in harmonically confined atomic Bose-Einstein condensates. This paper presents an overview of some of the common features and analogies experienced by these two intrinsically nonlinear systems, with emphasis on the stability of dark solitons in such systems and their decay via emission of radiation. The closely related issue of vortex dynamics in such systems is also briefly discussed
Parametric Driving of Dark Solitons in Atomic Bose-Einstein Condensates
Proukakis, N. P.; Parker, N. G.; Barenghi, C. F.; Adams, C. S.
2004-01-01
A dark soliton oscillating in an elongated harmonically-confined atomic Bose-Einstein condensate continuously exchanges energy with the sound field. Periodic optical `paddles' are employed to controllably enhance the sound density and transfer energy to the soliton, analogous to parametric driving. In the absence of damping, the amplitude of the soliton oscillations can be dramatically reduced, whereas with damping, a driven soliton equilibrates as a stable dark soliton with lower energy, the...
Output Coupler for Bose-Einstein Condensed Atoms
Energy Technology Data Exchange (ETDEWEB)
Mewes, M.; Andrews, M.; Kurn, D.; Durfee, D.; Townsend, C.; Ketterle, W. [Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
1997-01-01
We have demonstrated an output coupler for Bose condensed atoms in a magnetic trap. Short pulses of rf radiation were used to create Bose condensates in a superposition of trapped and untrapped hyperfine states. The fraction of out-coupled atoms was adjusted between 0% and 100% by varying the amplitude of the rf radiation. This configuration produces output pulses of coherent atoms and can be regarded as a pulsed {open_quotes}atom laser.{close_quotes} {copyright} {ital 1997} {ital The American Physical Society}
Spin-singlet Bose-Einstein condensation of two-electron atoms.
Takasu, Yosuke; Maki, Kenichi; Komori, Kaduki; Takano, Tetsushi; Honda, Kazuhito; Kumakura, Mitsutaka; Yabuzaki, Tsutomu; Takahashi, Yoshiro
2003-07-25
We report the observation of a Bose-Einstein condensation of ytterbium atoms by evaporative cooling in a novel crossed optical trap. Unlike the previously observed condensates, a ytterbium condensate is a two-electron system in a singlet state and has distinct features such as the extremely narrow intercombination transitions which are ideal for future optical frequency standard and the insensitivity to external magnetic field which is important for precision coherent atom optics, and the existence of the novel metastable triplet states generated by optical excitation from the singlet state. PMID:12906649
Photoionization of ultracold and Bose-Einstein-condensed Rb atoms
International Nuclear Information System (INIS)
Photoionization of a cold atomic sample offers intriguing possibilities for observing collective effects at extremely low temperatures. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap (MOT) with laser pulses ionizing through one-photon and two-photon absorption processes was performed. Losses and modifications in the density profile of the remaining trapped cold cloud or the remaining condensate sample were examined as functions of the ionizing laser parameters. Ionization cross sections were measured for atoms in a MOT, while in magnetic traps losses larger than those expected for ionization process were measured
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.
A phenomenological model of the growth of two-species atomic Bose-Einstein condensates
International Nuclear Information System (INIS)
We introduce a phenomenological mean-field model to describe the growth of immiscible two-species atomic Bose-Einstein condensates towards some equilibrium. Our model is based on the coupled Gross-Pitaevskii equations with the addition of dissipative terms to account for growth. While our model may be applied generally, we take a recent Rb-Cs experiment [McCarron et al., Phys. Rev. A 84 011603(R) (2011)] as a case study. As the condensates grow, they can pass through ranging transient density structures which can be distinct from the equilibrium states, although such a model always predicts the predominance of one condensate species over longer evolution times.
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.
Quantum Correlation of Many Atoms in Spinor Bose-Einstein Condensates
International Nuclear Information System (INIS)
In this letter, we have studied sub-Poissonian distributions and quantum correlation of atoms in spinor Bose-Einstein condensates. It is found that there exists the sub-Poissonian distributions for spin-1 and spin-(-1) components, respectively. There may exist the violation of the Cauchy-Schwartz inequality. For the same atomic numbers, the regions that include violation of the Cauchy-Schwartz inequality will shift rightwards with the increment of the Rabi frequency, whereas for the same Rabi frequency, the regions will shift leftwards with the increment of the atomic numbers.
Quantum Correlation of Many Atoms in Spinor Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
In this letter, we have studied sub-Poissonian distributions and quantum correlation of atoms in spinor Bose Einstein condensates. It is found that there exists the sub-Poissonian distributions for spin-1 and spin-(-1) components,respectively. There may exist the violation of the Cauchy-Schwartz inequality. For the same atomic numbers, the regions that include violation of the Cauchy-Schwartz inequality will shift rightwards with the increment of the Rabi frequency,whereas for the same Rabi frequency, the regions will shift leftwards with the increment of the atomic numbers.
Topological stirring of two-dimensional atomic Bose-Einstein condensates
International Nuclear Information System (INIS)
We stir vortices into a trapped quasi two-dimensional atomic Bose-Einstein condensate by moving three laser stirrers. We apply stirring protocols introduced by Boyland et al. (2000), that efficiently build in topological chaos in classical fluids and are classified as Pseudo-Anosov stirring protocols. These are compared to their inefficient mixing counterparts, finite-order stirring protocols. We investigate if inefficient stirring protocols result in a more clustered distribution of vortices. The efficiency with which vortices are 'mixed' or distributed in a condensate is important for investigating dynamics of continuously forced quantum turbulence and the existence of the inverse cascade in turbulent two-dimensional superfluids
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…
High-performance experimental apparatus for large atom number 87Rb Bose-Einstein condensates
International Nuclear Information System (INIS)
We describe our high-performance experimental apparatus for producing large atom number 87Rb Bose-Einstein condensates by using a double magneto-optical trap (MOT) system that consists of a two-dimensional MOT (2D MOT) and a three-dimensional MOT (3D MOT). As an atomic beam source for loading the 3D MOT, we use a unique 2D MOT system with two-color pushing beams, which increase the loading rate and the total number of atoms in the 3D MOT, compared to a pure 2D MOT by a factor of 20. After MOT compression and polarization gradient cooling, atoms are optically pumped into a magnetically trappable hyperfine state F = -1> to be loaded into a quadrupole-Ioffe-configuration (QUIC) trap. We enhance this optical pumping process by up to 300% by using two laser beams. After rf evaporative cooling, a Bose-Einstein condensate (BEC) with more than 2 x 107 atoms is achieved.
Generalized Bose-Einstein Condensation
Mullin, William J.; Sakhel, Asaad R.
2010-01-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We review examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically...
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
Posso Trujillo, Katerine; Rasel, Ernst M.; Gaaloul, Naceur; Quantus Team
Preparation of Bose Einstein condensates in realistc trapping potentials for precision atom interferometry Theoretical studies of the ground state and the dynamical properties of Bose Einstein condensates (BECs) are typically realized by considering the ensemble as being initiaally trapped by a harmonic potential. Dramatic discrepancies were found by comparing numerical results of the long-time expansion of BECs after being released from the harmonic trap, and measurements of the free evolution and delta-kick cooling (DKC) of a 87Rb BEC on large timescales of up to 2 s in micro-gravity (micro-g) environment such as those performed in the QUANTUS project from our group. The modification in the dynamics of a 87Rb BEC with the application of DKC by using experimentally implemented trapping geometries and the effect of gravity have been studied. Three different configurations have been considered: atom chip-based potential, dipole trap and the time-averaged orbiting potential. Such discrepancies may be crucial in high precision atom interferometry experiments in micro-g and zero-g platforms in which the implementation of DKC is mandatory to achieve the long-expansion times required
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.``
Entangled light from Bose-Einstein condensates
Ng, H. T.; Bose, S.
2008-01-01
We propose a method to generate entangled light with a Bose-Einstein condensate trapped in a cavity, a system realized in recent experiments. The atoms of the condensate are trapped in a periodic potential generated by a cavity mode. The condensate is continuously pumped by a laser and spontaneously emits a pair of photons of different frequencies in two distinct cavity modes. In this way, the condensate mediates entanglement between two cavity modes, which leak out and can be separated and e...
Bose-Einstein condensation of trapped atoms with dipole interactions
International Nuclear Information System (INIS)
The path-integral Monte Carlo method is used to simulate dilute trapped Bose gases and to investigate the equilibrium properties at finite temperatures. The quantum particles have a long-range dipole-dipole interaction and a short-range s-wave interaction. Using an anisotropic pseudopotential for the long-range dipolar interaction and a hard-sphere potential for the short-range s-wave interaction, we calculate the energetics and structural properties as a function of temperature and the number of particles. Also, in order to determine the effects of dipole-dipole forces and the influence of the trapping field on the dipolar condensate, we use two cylindrically symmetric harmonic confinements (a cigar-shaped trap and a disk-shaped trap). We find that the net effect of dipole-dipole interactions is governed by the trapping geometry. For a cigar-shaped trap, the net contribution of dipolar interactions is attractive and the shrinking of the density profiles is observed. For a disk-shaped trap, the net effect of long-range dipolar forces is repulsive and the density profiles expand
Analysis of a Bose-Einstein condensate double-well atom interferometer.
Faust, Douglas K; Reinhardt, William P
2010-12-10
Motivated by an open theoretical question in Bose-Einstein condensate atom interferometry, we introduce a novel computational method to describe the condensate order parameter in the presence of a central barrier. We are able to follow the full dynamics of the system during the raising of a barrier, from a single macroscopically occupied ground state to a state where imaging shows a split density and, finally, to the observation of a phase-controlled interference pattern. We are able to discriminate between a mean-field and a two-mode state via the Penrose-Onsager criterion. By simulating the first such experiment, where in spite of the observed splitting of the condensate density there is never more than a single macroscopically occupied state, we provide a definitive interpretation of these systems as a novel many-body form of Young's double-slit experiment. PMID:21231513
Analysis of a Bose-Einstein Condensate Double-Well Atom Interferometer
International Nuclear Information System (INIS)
Motivated by an open theoretical question in Bose-Einstein condensate atom interferometry, we introduce a novel computational method to describe the condensate order parameter in the presence of a central barrier. We are able to follow the full dynamics of the system during the raising of a barrier, from a single macroscopically occupied ground state to a state where imaging shows a split density and, finally, to the observation of a phase-controlled interference pattern. We are able to discriminate between a mean-field and a two-mode state via the Penrose-Onsager criterion. By simulating the first such experiment, where in spite of the observed splitting of the condensate density there is never more than a single macroscopically occupied state, we provide a definitive interpretation of these systems as a novel many-body form of Young's double-slit experiment.
Self-amplified gamma-ray laser on positronium atoms from a Bose-Einstein condensate.
Avetissian, H K; Avetissian, A K; Mkrtchian, G F
2014-07-11
A scheme of an intense coherent gamma-ray source based on the spontaneous radiation of positronium atoms in a Bose-Einstein condensate (BEC) due to two-photon collective annihilation decay is investigated analytically arising from the second quantized formalism. It is shown that because of the intrinsic instability of annihilation decay of BEC, the spontaneously emitted entangled photon pairs are amplified, leading to an exponential buildup of a macroscopic population into end-fire modes at a certain shape of the elongated condensate. The considered scheme may also be applied to a BEC of atoms or quasiparticles as a laser mechanism with double coherence to create entangled photonic beams with a macroscopic number of photons. PMID:25062185
Bose-Einstein condensation transition studies for atoms confined in Laguerre-Gaussian laser modes
Akin, T G; Dribus, Ben; Marzuola, Jeremy; Johnson, Lise; Alexander, Jason; Abraham, E R I
2011-01-01
Multiply-connected traps for cold, neutral atoms fix vortex cores of quantum gases. Laguerre-Gaussian laser modes are ideal for such traps due to their phase stability. We report theoretical calculations of the Bose-Einstein condensation transition properties and thermal characteristics of neutral atoms trapped in multiply connected geometries formed by Laguerre-Gaussian LG{p}{l} beams. Specifically, we consider atoms confined to the anti-node of a LG{0}{1} laser mode detuned to the red of an atomic resonance frequency, and those confined in the node of a blue-detuned LG{1}{1} beam. We compare the results of using the full potential to those approximating the potential minimum with a simple harmonic oscillator potential. We find that deviations between calculations of the full potential and the simple harmonic oscillator can be up to 3%-8% for trap parameters consistent with typical experiments.
Remote Entanglement between a Single Atom and a Bose-Einstein Condensate
Lettner, M; Riedl, S; Vo, C; Hahn, C; Baur, S; Bochmann, J; Ritter, S; Dürr, S; Rempe, G
2011-01-01
Entanglement between stationary systems at remote locations is a key resource for quantum networks. We report on the experimental generation of remote entanglement between a single atom inside an optical cavity and a Bose-Einstein condensate (BEC). To produce this, a single photon is created in the atom-cavity system, thereby generating atom-photon entanglement. The photon is transported to the BEC and converted into a collective excitation in the BEC, thus establishing matter-matter entanglement. After a variable delay, this entanglement is converted into photon-photon entanglement. The matter-matter entanglement lifetime of 100 $\\mu$s exceeds the photon duration by two orders of magnitude. The total fidelity of all concatenated operations is 95%. This hybrid system opens up promising perspectives in the field of quantum information.
Ultracold molecules from a Bose-Einstein condensate of cesium atoms
International Nuclear Information System (INIS)
Full text: We have realized a source of ultracold molecules by applying a Feshbach sweep to an atomic Bose-Einstein condensate of Cs atoms. The ability to separate the molecules from the atoms in a Stern-Gerlach type experiment allows a direct measurement of the molecular magnetic moment, the lifetime of the molecules, and of the molecular momentum distribution. We infer a magnetic moment of 0.941 Bohr magnetons, a free space lifetime of 200 ms, and a temperature of 15(5) nK. Future experiments should allow for optical trapping of the molecules. The possibility to directly observe the evolution of an ultra cold molecular ensemble opens up many new avenues for research, e.g., concerning the macroscopic coherence properties of a molecular quantum gas or applications in molecular optics and interferometry. (author)
International Nuclear Information System (INIS)
The hydrodynamics of quantized vortices and solitons in an atomic Bose-Einstein condensate excited by an oscillating potential are studied by numerically solving the two-dimensional Gross-Pitaevskii equation. The oscillating potential keeps nucleating vortex dipoles, whose impulses alternately change their direction synchronously with the oscillation of the potential. This leads to synergy dynamics of vortices and solitons in quantum fluids.
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.
Bose-Einstein condensation and heat capacity of two-dimensional spin-polarized atomic hydrogen
International Nuclear Information System (INIS)
The static fluctuation approximation (SFA) is used to study the condensate fraction and the specific heat capacity of finite two-dimensional spin-polarized atomic hydrogen. It is found that Bose-Einstein condensation occurs in this system. The transition temperature at different densities decreases as the number of particles of the system increases. At low density, a sharp peak in the specific heat capacity is observed at the transition temperature. On the other hand, as the density of the system increases, the transition temperature becomes no longer well-defined, and a hump is observed in the specific heat capacity around the transition temperature. A qualitative comparison of our results to published results for finite Bose systems shows good agreement.
Reconstructing the quantum state of a Bose-Einstein condensate of atoms in two hyperfine levels
International Nuclear Information System (INIS)
We describe an atomic interferometer based on Raman transitions between two hyperfine states. We show how atom count probabilities at the output of the interferometer can be used to reconstruct the joint, entangled multi-particle state of a Bose-Einstein condensate with fixed total number. Two data collection schemes are compared, by numerically solving for the density matrix from the probability data and making analytical estimates of the errors. When only the phase of the interferometer is varied, state reconstruction is possible but ill-conditioned for the case of an unbalanced beamsplitter. When both the phase and transmission parameters are varied, the two-mode Q-function can be measured directly and the reconstruction of the state is well-conditioned. (author)
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 ...
Topics relating to atomic collisions in dilute Bose-Einstein condensates
International Nuclear Information System (INIS)
In this thesis, we investigate various aspects of applications and limitations arising from atomic collisions in dilute Bose-Einstein condensates. First, we investigate the relative particle number squeezing produced in the excited states of a dilute condensate at zero temperature using stimulated light scattering. We show that a modest number of relative number squeezed particles can be achieved when atoms, produced in pairs through collisions in the condensate, are scattered out by their interaction with the lasers. This squeezing is optimal when the momentum is larger than the inverse healing length. This modest number of relative number squeezed particles has the potential to be amplified in four-wave-mixing experiments. We study the limitations on the relative number squeezing between photons and atoms coupled out from a homogeneous Bose-Einstein condensate. We consider the coupling between the translational atomic states by two photon Bragg processes, one of the photon modes involved in the Bragg process being in a coherent state, and the other initially unpopulated. We start with an interacting condensate at zero temperature and compute the time evolution for the system. We discuss how collisions between the atoms and photon rescattering affect the degree of squeezing which may be reached in such experiments. We investigate the limitations arising from atomic collisions on the storage and delay times of probe pulses in EIT experiments. We find that the atomic collisions can be described by an effective decay rate that limits storage and delay times. We calculate the momentum and temperature dependence of the decay rate and find that it is necessary to excite atoms to a particular momentum depending on temperature and spacing of the energy levels involved in order to minimize the decoherence effects of atomic collisions. Finally, we propose a method to probe states in the Mott insulator regime produced from a condensate in an optical lattice. We consider a
Bose-Einstein condensates in optical gratings
International Nuclear Information System (INIS)
Full text: Different experiments of atomic physics and quantum optics performed with a Bose Einstein condensate of rubidium atoms are presented. Condensate are dense atomic samples described by a single wave function for the external and internal degrees of freedom. They allow to investigate with high resolution the atomic interaction with electromagnetic fields in different configurations. We have investigated the motion of a condensate within an inhomogeneous magnetic field. If the magnetic field varies slowly enough in space, the effective Hamiltonian governing the dynamics of the slow external variables contains an induced gauge potential, the so-called geometric potential, and in the classical limit geometric forces acting on a neutral particle with a magnetic moment. Our measurements on the motion of a rubidium Bose-Einstein condensate in a time dependent magnetic trap have provided direct evidence for these geometric forces. The properties of Bose-Einstein condensates in lower dimensional trapping potentials have recently attracted increasing interest. 2D condensates can be created in an array of pancake-shaped traps provided by the periodic potential of a 1 D optical lattice. We have investigated Bose-Einstein condensate in an accelerated optical lattice and associated phenomena such as Bloch oscillations and Landau-Zener tunnelling. Furthermore we have investigated the dynamics and phase evolution of Bose-Einstein condensates in 1 D optical lattices. Photoionization of a cold atomic sample offers intriguing possibilities to observe collective effects at extremely low temperatures. Close enough to threshold even the quantum statistics of the products, which are Fermions produced out of quantum degenerate Bosons, may influence the ionization rate itself. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap with laser pulses ionizing through 1-photon and 2-photon absorptions processes has been performed. Losses and the
Self-consistent effects of continuous wave output coupling of atoms from a Bose-Einstein condensate
Hutchinson, D. A. W.
1998-01-01
We present a self-consistent mean field model of the extraction of atoms from a Bose-Einstein condensate to form a CW atom laser. The model is based upon the Hartree-Fock Bogoliubov equations within the Popov approximation, modified by the inclusion of spatially dependent source and sink terms, which lead to current flow within the condensate. The effects of this current flow are investigated for traps containing Rubidium (repulsive effective interaction) and Lithium (attractive interaction) ...
Generalized Bose-Einstein Condensation
Mullin, William J
2010-01-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We analyze examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically occupied. We begin by discussing Type I or "normal" BEC into a single state for an isotropic harmonic oscillator potential. Other geometries and external potentials are then considered: the "channel" potential (harmonic in one dimension and hard-wall in the other), which displays Type II, the "cigar trap" (anisotropic harmonic potential), and the "Casimir prism" (an elongated box), the latter two having Type III condensations. General box geometries are considered in an appendix. We particularly focus on the cigar trap,...
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...
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 ...
Multiple atomic dark solitons in cigar-shaped Bose-Einstein condensates
International Nuclear Information System (INIS)
We consider the stability and dynamics of multiple dark solitons in cigar-shaped Bose-Einstein condensates. Our study is motivated by the fact that multiple matter-wave dark solitons may naturally form in such settings as per our recent work [Phys. Rev. Lett. 101, 130401 (2008)]. First, we study the dark soliton interactions and show that the dynamics of well-separated solitons (i.e., ones that undergo a collision with relatively low velocities) can be analyzed by means of particle-like equations of motion. The latter take into regard the repulsion between solitons (via an effective repulsive potential) and the confinement and dimensionality of the system (via an effective parabolic trap for each soliton). Next, based on the fact that stationary, well-separated dark multisoliton states emerge as a nonlinear continuation of the appropriate excited eigenstates of the quantum harmonic oscillator, we use a Bogoliubov-de Gennes analysis to systematically study the stability of such structures. We find that for a sufficiently large number of atoms, multiple soliton states are dynamically stable, while for a small number of atoms, we predict a dynamical instability emerging from resonance effects between the eigenfrequencies of the soliton modes and the intrinsic excitation frequencies of the condensate. Finally, we present experimental realizations of multisoliton states including a three-soliton state consisting of two solitons oscillating around a stationary one and compare the relevant results to the predictions of the theoretical mean-field model.
Physics of Ultra-Cold Matter Atomic Clouds, Bose-Einstein Condensates and Rydberg Plasmas
Mendonça, J T
2013-01-01
The advent of laser cooling of atoms led to the discovery of ultra-cold matter, with temperatures below liquid Helium, which displays a variety of new physical phenomena. Physics of Ultra-Cold Matter gives an overview of this recent area of science, with a discussion of its main results and a description of its theoretical concepts and methods. Ultra-cold matter can be considered in three distinct phases: ultra-cold gas, Bose Einstein condensate, and Rydberg plasmas. This book gives an integrated view of this new area of science at the frontier between atomic physics, condensed matter, and plasma physics. It describes these three distinct phases while exploring the differences, as well as the sometimes unexpected similarities, of their respective theoretical methods. This book is an informative guide for researchers, and the benefits are a result from an integrated view of a very broad area of research, which is limited in previous books about this subject. The main unifying tool explored in this book is the ...
Lee, Chaohong; Shi, Lei; Zhu, Xiwen; Gao, Kelin; Hai, Wenhua; Duan, Yiwu; Liu, Wing-Ki
2000-01-01
We have investigated the chaotic atomic population oscillations between two coupled Bose-Einstein condensates (BEC) with time-dependent asymmetric trap potential. In the perturbative regime, the population oscillations can be described by the Duffing equation, and the chaotic oscillations near the separatrix solution are analyzed. The sufficient-necessary conditions for stable oscillations depend on the physical parameters and initial conditions sensitively. The first-order necessary conditio...
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.
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.
Ground state and excitations of a Bose-Einstein condensate of atoms and their diatomic bound states
International Nuclear Information System (INIS)
We study theoretically a many-body system of spinless atoms and their diatomic bound states (or molecules) which form a single Bose-Einstein condensate at zero temperature. The equilibrium states of such a system and its dynamics are analyzed within the Gross-Pitaevskii approach. It is shown that the system exhibits two phases depending on binding energy value: it can be in the states with atomic-molecular condensate or molecular condensate. The basic thermodynamic characteristics of the two phases and their stability conditions are obtained. Both phases are characterized by two branches of collective excitations. The first branch is acoustic mode and the second one is gapfull
Recent developments in Bose-Einstein condensation
Energy Technology Data Exchange (ETDEWEB)
Kalman, G.
1997-09-22
This paper contains viewgraphs on developments on Bose-Einstein condensation. Some topics covered are: strongly coupled coulomb systems; standard response functions of the first and second kind; dynamical mean field theory; quasi localized charge approximation; and the main equations.
Multiple atomic dark solitons in cigar-shaped Bose-Einstein condensates
Theocharis, G.; Weller, A.; Ronzheimer, J. P.; Gross, C.; Oberthaler, M. K.; Kevrekidis, P. G.; Frantzeskakis, D. J.
2010-06-01
We consider the stability and dynamics of multiple dark solitons in cigar-shaped Bose-Einstein condensates. Our study is motivated by the fact that multiple matter-wave dark solitons may naturally form in such settings as per our recent work [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.101.130401 101, 130401 (2008)]. First, we study the dark soliton interactions and show that the dynamics of well-separated solitons (i.e., ones that undergo a collision with relatively low velocities) can be analyzed by means of particle-like equations of motion. The latter take into regard the repulsion between solitons (via an effective repulsive potential) and the confinement and dimensionality of the system (via an effective parabolic trap for each soliton). Next, based on the fact that stationary, well-separated dark multisoliton states emerge as a nonlinear continuation of the appropriate excited eigenstates of the quantum harmonic oscillator, we use a Bogoliubov-de Gennes analysis to systematically study the stability of such structures. We find that for a sufficiently large number of atoms, multiple soliton states are dynamically stable, while for a small number of atoms, we predict a dynamical instability emerging from resonance effects between the eigenfrequencies of the soliton modes and the intrinsic excitation frequencies of the condensate. Finally, we present experimental realizations of multisoliton states including a three-soliton state consisting of two solitons oscillating around a stationary one and compare the relevant results to the predictions of the theoretical mean-field model.
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)
Multiple atomic dark solitons in cigar-shaped Bose-Einstein condensates
Theocharis, G.; Weller, A.; Ronzheimer, J. P.; Gross, C.; Oberthaler, M. K.; Kevrekidis, P. G.; Frantzeskakis, D. J.
2009-01-01
We consider the stability and dynamics of multiple dark solitons in cigar-shaped Bose-Einstein condensates (BECs). Our study is motivated by the fact that multiple matter-wave dark solitons may naturally form in such settings as per our recent work [Phys. Rev. Lett. 101, 130401 (2008)]. First, we study the dark soliton interactions and show that the dynamics of well-separated solitons (i.e., ones that undergo a collision with relatively low velocities) can be analyzed by means of particle-lik...
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)
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)
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...
Generalized Bose-Einstein Condensation
Mullin, William J.; Sakhel, Asaad R.
2012-02-01
Generalized Bose-Einstein condensation (GBEC) involves condensates appearing simultaneously in multiple states. We review examples of the three types in an ideal Bose gas with different geometries. In Type I there is a discrete number of quantum states each having macroscopic occupation; Type II has condensation into a continuous band of states, with each state having macroscopic occupation; in Type III each state is microscopically occupied while the entire condensate band is macroscopically occupied. We begin by discussing Type I or "normal" BEC into a single state for an isotropic harmonic oscillator potential. Other geometries and external potentials are then considered: the "channel" potential (harmonic in one dimension and hard-wall in the other), which displays Type II, the "cigar trap" (anisotropic harmonic potential), and the "Casimir prism" (an elongated box), the latter two having Type III condensations. General box geometries are considered in an appendix. We particularly focus on the cigar trap, which Van Druten and Ketterle first showed had a two-step condensation: a GBEC into a band of states at a temperature T c and another "one-dimensional" transition at a lower temperature T 1 into the ground state. In a thermodynamic limit in which the ratio of the dimensions of the anisotropic harmonic trap is kept fixed, T 1 merges with the upper transition, which then becomes a normal BEC. However, in the thermodynamic limit of Beau and Zagrebnov, in which the ratio of the boundary lengths increases exponentially, T 1 becomes fixed at the temperature of a true Type I phase transition. The effects of interactions on GBEC are discussed and we show that there is evidence that Type III condensation may have been observed in the cigar trap.
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...
Johnson, T H; Yuan, Y; Bao, W; Clark, S R; Foot, C; Jaksch, D
2016-06-17
We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes. PMID:27367366
Johnson, T. H.; Yuan, Y.; Bao, W.; Clark, S. R.; Foot, C.; Jaksch, D.
2016-06-01
We investigate cold bosonic impurity atoms trapped in a vortex lattice formed by condensed bosons of another species. We describe the dynamics of the impurities by a bosonic Hubbard model containing occupation-dependent parameters to capture the effects of strong impurity-impurity interactions. These include both a repulsive direct interaction and an attractive effective interaction mediated by the Bose-Einstein condensate. The occupation dependence of these two competing interactions drastically affects the Hubbard model phase diagram, including causing the disappearance of some Mott lobes.
Bose-Einstein condensation in a vapor of sodium atoms in an electric field
You, Pei-Lin
2016-06-01
Bose-Einstein condensation (BEC) at normal temperature (T=343K) has been observed because an electric field was first applied. There are two ways to achieve phase transition: lower the temperature of Bose gas or increase its density. This article provides more appropriate method: increase the voltage. In theory, 3s and 3p states of sodium are not degenerate, but Na may be polar atom doesnot conflict with quantum mechanics because it is hydrogen-like atom. Our innovation lies in we applied an electric field used for the orientation polarization. Na vapor was filled in a cylindrical capacitor. In order to determine the polarity of sodium, we measured the capacitance at different temperatures. If Na is non-polar atom, its capacitance should be independent of temperature because the nucleus of atom is located at the center of the electron cloud. But our experiment shows that its capacitance is related to temperature, so Na is polar atom. In order to achieve Na vapor phase transition, we measured the capacitance at different voltages. From the entropy of Na vapor S=0, the critical voltage Vc=68volts. When V0; when V>Vc, the atoms become aligned with the field Svapor entered quasi-vacuum state. We create a BEC with 2.506×1017 atoms, condensate fraction reached 98.9%. This is BEC in momentum space. Our experiment shows that if a Bose gas enters quasi-vacuum state, this also means that it underwent phase transition and generates BEC. Therefore, quasi-vacuum state of alkali gas is essentially large-scale BEC. This is an unexpected discovery. BEC and vacuum theory are two unrelated research areas, but now they are closely linked together. The maximum induced dipole moment dind≤7.8×10-15 e cm can be neglected. Ultra-low temperature is in order to make Bose gas phase transition, we achieve the phase transition by the critical voltage, so the ultra-low temperature is not necessary. According to the standard proposed by Ketterle, although we didn't use laser cooling atoms
Bose-Einstein Condensation of Metastable Helium
Dos Santos, F. Pereira; Léonard, J.; Wang, Junmin; Barrelet, C. J.; Perales, F.; Rasel, E.; Unnikrishnan, C. S.; Leduc, M.; Cohen-Tannoudji, C.
2001-04-01
We have observed a Bose-Einstein condensate in a dilute gas of 4He in the 32S1 metastable state. We find a critical temperature of \\(4.7+/-0.5\\) μK and a typical number of atoms at the threshold of 8×106. The maximum number of atoms in our condensate is about 5×105. An approximate value for the scattering length a = \\(16+/-8\\) nm is measured. The mean elastic collision rate at threshold is then estimated to be about 2×104 s-1, indicating that we are deeply in the hydrodynamic regime. The typical decay time of the condensate is 2 s, which places an upper bound on the rate constants for two-body and three-body inelastic collisions.
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)
International Nuclear Information System (INIS)
We present a feedback control scheme that designs time-dependent laser-detuning frequency to suppress possible dynamical instability in coupled free-quasibound-bound atom-molecule condensate systems. The proposed adaptive frequency chirp with feedback is shown to be highly robust and very efficient in the passage from an atomic to a stable molecular Bose-Einstein condensate
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.
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.
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.
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.
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.
Optimized production of large Bose Einstein Condensates
Comparat, D; Fioretti, A; Pillet, P; Stern, G; Tolra, B L
2006-01-01
We suggest different simple schemes to efficiently load and evaporate a ''dimple'' crossed dipolar trap. The collisional processes between atoms which are trapped in a reservoir load in a non adiabatic way the dimple. The reservoir trap can be provided either by a dark SPOT Magneto Optical Trap, the (aberrated) laser beam itself or by a quadrupolar or quadratic magnetic trap. Optimal parameters for the dimple are derived from thermodynamical equations and from loading time, including possible inelastic and Majorana losses. We suggest to load at relatively high temperature a tight optical trap. Simple evaporative cooling equations, taking into account gravity, the possible occurrence of hydrodynamical regime, Feshbach resonance processes and three body recombination events are given. To have an efficient evaporation the elastic collisional rate (in s$^{-1}$) is found to be on the order of the trapping frequency and lower than one hundred times the temperature in micro-Kelvin. Bose Einstein condensates with mor...
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.
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.
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)
Loading Bose-Einstein-condensed atoms into the ground state of an optical lattice
International Nuclear Information System (INIS)
We optimize the turning on of a one-dimensional optical potential, VL(x,t)=S(t)V0 cos2(kx) to obtain the optimal turn-on function S(t) so as to load a Bose-Einstein condensate into the ground state of the optical lattice of depth V0. Specifically, we minimize interband excitations at the end of the turn-on of the optical potential at the final ramp time tr, where S(tr)=1, given that S(0)=0. Detailed numerical calculations confirm that a simple unit cell model is an excellent approximation when the turn-on time tr is long compared with the inverse of the band excitation frequency and short in comparison with nonlinear time (ℎ/2π)/μ where μ is the chemical potential of the condensate. We demonstrate using the Gross-Pitaevskii equation with an optimal turn-on function S(t) that the ground state of the optical lattice can be loaded with no significant excitation even for times tr on the order of the inverse band excitation frequency
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.
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
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.
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.
Multiple atomic dark solitons in cigar-shaped Bose-Einstein condensates
Theocharis, G; Ronzheimer, J P; Gross, C; Oberthaler, M K; Kevrekidis, P G; Frantzeskakis, D J
2009-01-01
We consider the stability and dynamics of multiple dark solitons in cigar-shaped Bose-Einstein condensates (BECs). Our study is motivated by the fact that multiple matter-wave dark solitons may naturally form in such settings as per our recent work [Phys. Rev. Lett. 101, 130401 (2008)]. First, we study the dark soliton interactions and show that the dynamics of well-separated solitons (i.e., ones that undergo a collision with relatively low velocities) can be analyzed by means of particle-like equations of motion. The latter take into regard the repulsion between solitons (via an effective repulsive potential) and the confinement and dimensionality of the system (via an effective parabolic trap for each soliton). Next, based on the fact that stationary, well-separated dark multi-soliton states emerge as a nonlinear continuation of the appropriate excited eigensates of the quantum harmonic oscillator, we use a Bogoliubov-de Gennes analysis to systematically study the stability of such structures. We find that ...
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...
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)
International Nuclear Information System (INIS)
In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)
Lee, C; Zhu, X; Gao, K; Hai, W; Duan Yi Shi; Liu, W K; Lee, Chaohong; Shi, Lei; Zhu, Xiwen; Gao, Kelin; Hai, Wenhua; Duan, Yiwu; Liu, Wing-Ki
2001-01-01
We have investigated the chaotic atomic population oscillations between two coupled Bose-Einstein condensates (BEC) with time-dependent asymmetric trap potential. In the perturbative regime, the population oscillations can be described by the Duffing equation, and the chaotic oscillations near the separatrix solution are analyzed. The sufficient-necessary conditions for stable oscillations depend on the physical parameters and initial conditions sensitively. The first-order necessary condition indicates that the Melnikov function is equal to zero, so the stable oscillations are Melnikov chaotic. For the ordinary parameters and initial conditions, the chaotic dynamics is simulated with numerical calculation. If the damping is absent, with the increasing of the trap asymmetry, the regular oscillations become chaotic gradually, the corresponding stroboscopic Poincare sections (SPS) vary from a single island to more islands, and then the chaotic sea. For the completely chaotic oscillations, the long-term localiza...
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.
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.
Hysteresis effects in Bose-Einstein condensates
Sacchetti, Andrea
2010-01-01
Here, we consider damped two-components Bose-Einstein condensates with many-body interactions. We show that, when the external trapping potential has a double-well shape and when the nonlinear coupling factors are modulated in time, hysteresis effects may appear under some circumstances. Such hysteresis phenomena are a result of the joint contribution between the appearance of saddle node bifurcations and damping effect.
Cosmic Axion Bose-Einstein Condensation
Banik, Nilanjan; Sikivie, Pierre
2015-01-01
QCD axions are a well-motivated candidate for cold dark matter. Cold axions are produced in the early universe by vacuum realignment, axion string decay and axion domain wall decay. We show that cold axions thermalize via their gravitational self-interactions, and form a Bose-Einstein condensate. As a result, axion dark matter behaves differently from the other proposed forms of dark matter. The differences are observable.
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...
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 ...
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)
Inhibition of Coherence in Trapped Bose-Einstein Condensates
International Nuclear Information System (INIS)
We analyze the dependence of the collapse and revival of many-atom coherence of a trapped Bose-Einstein condensate on the trap potential, dimensionality of the gas, and atom number fluctuations. We show that in a class of experimentally relevant systems the collapse time vanishes in the limit of a large number of atoms, implying that the trapped Bose gas cannot sustain a well-defined quantum phase. copyright 1997 The American Physical Society
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.
Non-Ground-State Bose-Einstein Condensates of Trapped Atoms
V. I. Yukalov; Yukalova, E. P.; V. S. Bagnato
1997-01-01
The possibility of creating a Bose condensate of trapped atoms in a non-ground state is suggested. Such a nonequilibrium Bose condensate can be formed if one, first, obtains the conventional Bose condensate in the ground state and then transfers the condensed atoms to a non-ground state by means of a resonance pumping. The properties of ground and non-ground states are compared and plausible applications of such nonequilibrium condensates are discussed.
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.
A Bose-Einstein condensate in a microtrap
International Nuclear Information System (INIS)
We describe an experiment to create a sizable 87Rb Bose-Einstein condensate (BEC) in a simple magnetic microtrap, created by a current through a Z-shaped wire and a homogeneous bias field. The BEC is created close to a reflecting surface. It is an ideal coherent source for experiments with cold atoms close to surfaces, be it small-volume microtraps or directly studying the interactions between cold atoms and a warm surface
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.
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.
Energy Technology Data Exchange (ETDEWEB)
Perrin, A
2007-11-15
In this thesis, we report on the observation of pairs of correlated atoms produced in the collision of two Bose-Einstein condensates of metastable helium. Three laser beams perform a Raman transfer which extracts the condensate from the magnetic trap and separates it into two parts with opposite mean momenta. While the condensates propagate, elastic scattering of pairs of atoms occurs, whose momenta satisfy energy and momentum conservation laws. Metastable helium atoms large internal energy allows the use of a position-sensitive, single-atom detector which permits a three-dimensional reconstruction of the scattered atoms'momenta. The statistics of these momenta show correlations for atoms with opposite momenta. The measured correlation volume can be understood from the uncertainty-limited momentum spread of the colliding condensates. This interpretation is confirmed by the observation of the momentum correlation function for two atoms scattered in the same direction. This latter effect is a manifestation of the Hanbury Brown-Twiss effect for indistinguishable bosons. Such a correlated-atom-pair source is a first step towards experiments in which one would like to confirm the pairs'entanglement. (author)
Analog gravity from Bose-Einstein condensates
Barcelo, Carlos; Liberati, Stefano; Visser, Matt
2000-01-01
We analyze prospects for the use of Bose-Einstein condensates as condensed-matter systems suitable for generating a generic ``effective metric'', and for mimicking kinematic aspects of general relativity. We extend the analysis due to Garay et al, [gr-qc/0002015, gr-qc/0005131]. Taking a long term view, we ask what the ultimate limits of such a system might be. To this end, we consider a very general version of the nonlinear Schrodinger equation (with a 3-tensor position-dependent mass and ar...
The Atomic Tunneling Current in Two-Species Bose-Einstein Condensates
Institute of Scientific and Technical Information of China (English)
YU Zhao-Xian; JIAO Zhi-Yong
2001-01-01
It is shown that the atomic tunneling current and the Shapiro-like steps strongly depend on the initial number of atoms in each condensate and the initial phase difference between the two condensates which are initially in even (odd) coherent states. The nonlinearity of interatomic interactions in the two condensates may lead to the atomic tunneling current and Shapiro-like step between the two condensates. It is found that the interatomic nonlinear interactions can induce the atomic tunneling current and Shapiro-like step between two condensates even though there does not exist the interspecies Josephson-like tunneling coupling. The static atomic tunneling current flows in positive or negative direction, which depends on the phase difference of the two-species condensates.
Bose-Einstein condensation of photons in an optical microcavity
Klaers, Jan; Schmitt, Julian; Vewinger, Frank; Weitz, Martin
2010-01-01
Bose-Einstein condensation, the macroscopic ground state accumulation of particles with integer spin (bosons) at low temperature and high density, has been observed in several physical systems, including cold atomic gases and solid state physics quasiparticles. However, the most omnipresent Bose gas, blackbody radiation (radiation in thermal equilibrium with the cavity walls) does not show this phase transition, because the chemical potential of photons vanishes and, when the temperature is r...
Yao, Yu-Qin; Li, Ji; Han, Wei; Wang, Deng-Shan; Liu, Wu-Ming
2016-01-01
The intrinsic nonlinearity is the most remarkable characteristic of the Bose-Einstein condensates (BECs) systems. Many studies have been done on atomic BECs with time- and space- modulated nonlinearities, while there is few work considering the atomic-molecular BECs with space-modulated nonlinearities. Here, we obtain two kinds of Jacobi elliptic solutions and a family of rational solutions of the atomic-molecular BECs with trapping potential and space-modulated nonlinearity and consider the effect of three-body interaction on the localized matter wave solutions. The topological properties of the localized nonlinear matter wave for no coupling are analysed: the parity of nonlinear matter wave functions depends only on the principal quantum number n, and the numbers of the density packets for each quantum state depend on both the principal quantum number n and the secondary quantum number l. When the coupling is not zero, the localized nonlinear matter waves given by the rational function, their topological properties are independent of the principal quantum number n, only depend on the secondary quantum number l. The Raman detuning and the chemical potential can change the number and the shape of the density packets. The stability of the Jacobi elliptic solutions depends on the principal quantum number n, while the stability of the rational solutions depends on the chemical potential and Raman detuning. PMID:27403634
Yao, Yu-Qin; Li, Ji; Han, Wei; Wang, Deng-Shan; Liu, Wu-Ming
2016-01-01
The intrinsic nonlinearity is the most remarkable characteristic of the Bose-Einstein condensates (BECs) systems. Many studies have been done on atomic BECs with time- and space- modulated nonlinearities, while there is few work considering the atomic-molecular BECs with space-modulated nonlinearities. Here, we obtain two kinds of Jacobi elliptic solutions and a family of rational solutions of the atomic-molecular BECs with trapping potential and space-modulated nonlinearity and consider the effect of three-body interaction on the localized matter wave solutions. The topological properties of the localized nonlinear matter wave for no coupling are analysed: the parity of nonlinear matter wave functions depends only on the principal quantum number n, and the numbers of the density packets for each quantum state depend on both the principal quantum number n and the secondary quantum number l. When the coupling is not zero, the localized nonlinear matter waves given by the rational function, their topological properties are independent of the principal quantum number n, only depend on the secondary quantum number l. The Raman detuning and the chemical potential can change the number and the shape of the density packets. The stability of the Jacobi elliptic solutions depends on the principal quantum number n, while the stability of the rational solutions depends on the chemical potential and Raman detuning. PMID:27403634
Bose-Einstein condensation in layered systems
Haerdig, A
1993-01-01
The thermodynamic properties of an ideal gas of bosons moving freely within layered planes and having a finite amplitude for jumping between neighbouring planes, are derived. As long as this coupling is non-zero, the system becomes effectively two-dimensional at sufficiently high temperatures. At a correspondingly low temperature it undergoes a Bose-Einstein transition into a condensed phase as in three dimensions. Below the critical temperature the specific heat is a universal function of only one dimensionless system variable. The phase transition becomes weaker as the coupling between the planes decreases and eventually disappears when the planes decouple. (author)
Analog gravity from Bose-Einstein condensates
Barcelo, C; Visser, M; Barcelo, Carlos; Liberati, Stefano; Visser, Matt
2001-01-01
We analyze prospects for the use of Bose-Einstein condensates as condensed-matter systems suitable for generating a generic ``effective metric'', and for mimicking kinematic aspects of general relativity. We extend the analysis due to Garay et al, [gr-qc/0002015, gr-qc/0005131]. Taking a long term view, we ask what the ultimate limits of such a system might be. To this end, we consider a very general version of the nonlinear Schrodinger equation (with a 3-tensor position-dependent mass and arbitrary nonlinearity). Such equations can be used for example in discussing Bose-Einstein condensates in heterogeneous and highly nonlinear systems. We demonstrate that at low momenta linearized excitations of the phase of the condensate wavefunction obey a (3+1)-dimensional d'Alembertian equation coupling to a (3+1)-dimensional Lorentzian-signature ``effective metric'' that is generic, and depends algebraically on the background field. Thus at low momenta this system serves as an analog for the curved spacetime of genera...
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.
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.
Chen, Qijin
2016-01-01
BCS–Bose-Einstein condensation (BEC) crossover is effected by increasing pairing strength between fermions from weak to strong in the particle-particle channel, and has attracted a lot of attention since the experimental realization of quantum degenerate atomic Fermi gases. Here we study the effect of the (often dropped) particle-hole channel on the zero T gap Δ(0), superfluid transition temperature Tc, the pseudogap at Tc, and the mean-field ratio 2Δ(0)/, from BCS through BEC regimes, using a pairing fluctuation theory which includes self-consistently the contributions of finite-momentum pairs and features a pseudogap in single particle excitation spectrum. Summing over the infinite particle-hole ladder diagrams, we find a complex dynamical structure for the particle-hole susceptibility χph, and conclude that neglecting the self-energy feedback causes a serious over-estimate of χph. While our result in the BCS limit agrees with Gor’kov et al., the particle-hole channel effect becomes more complex and pronounced in the crossover regime, where χph is reduced by both a smaller Fermi surface and a big (pseudo)gap. Deep in the BEC regime, the particle-hole channel contributions drop to zero. We predict a density dependence of the magnetic field at the Feshbach resonance, which can be used to quantify χph and test different theories. PMID:27183875
Chen, Qijin
2016-05-01
BCS–Bose-Einstein condensation (BEC) crossover is effected by increasing pairing strength between fermions from weak to strong in the particle-particle channel, and has attracted a lot of attention since the experimental realization of quantum degenerate atomic Fermi gases. Here we study the effect of the (often dropped) particle-hole channel on the zero T gap Δ(0), superfluid transition temperature Tc, the pseudogap at Tc, and the mean-field ratio 2Δ(0)/, from BCS through BEC regimes, using a pairing fluctuation theory which includes self-consistently the contributions of finite-momentum pairs and features a pseudogap in single particle excitation spectrum. Summing over the infinite particle-hole ladder diagrams, we find a complex dynamical structure for the particle-hole susceptibility χph, and conclude that neglecting the self-energy feedback causes a serious over-estimate of χph. While our result in the BCS limit agrees with Gor’kov et al., the particle-hole channel effect becomes more complex and pronounced in the crossover regime, where χph is reduced by both a smaller Fermi surface and a big (pseudo)gap. Deep in the BEC regime, the particle-hole channel contributions drop to zero. We predict a density dependence of the magnetic field at the Feshbach resonance, which can be used to quantify χph and test different theories.
Quantum field theory and Bose Einstein condensation
Bedingham, D J
2001-01-01
We study the phenomenon of Bose-Einstein condensation in cosmological and laboratory situations. To do this we examine the extreme temperature limits of a self-interacting O(2)-invariant scalar field theory with a non-zero charge density. The transition point has been well known for a long time in the case of an interactionless theory. However, due to a combination of technical problems imposed by having interactions and finite density, the transition in the interacting theory is not well understood. Here, in order to probe the Bose-Einstein condensation transition we perform a dimensional reduction of the 4D O(2)-invariant theory to give an effective theory in 3D. After dimensional reduction we use the 3D effective theory to calculate the two-loop effective potential which is used to examine the phase structure. This is a perturbative calculation and is still inappropriate for looking at the critical temperature. To find the critical temperature we use the non-perturbative linear delta expansion on the effec...
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].
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.
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.
Coherent atom-trimer conversion in a repulsive bose-einstein condensate
International Nuclear Information System (INIS)
In our recent work, we studied the constructive interference between two chemical reaction channels in the process of coherent atom- trimer conversion in a repulsive atomic Bose condensate. This interference can be viewed as a double-slit-like interference in quantum degenerate matter-wave chemistry (superchemistry). The constructive interference can lead to a significant enhancement of trimer production, leading to a new technique for coherent assembly and control of ultracold heteronuclear molecules. (authors)
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
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.
International Nuclear Information System (INIS)
In this work a two-particle irreducible (2PI) closed-time-path (CTP) effective action is used to describe the nonequilibrium dynamics of a Bose-Einstein condensate selectively loaded into every third site of a one-dimensional optical lattice. The motivation of this work is the recent experimental realization of this system. Patterned loading methods may be useful for quantum computing with trapped atoms. This system also serves to illustrate many basic issues in nonequilibrium quantum-field theory pertaining to the dynamics of quantum correlations and fluctuations which goes beyond the capability of a mean-field theory. By numerically evolving in time the initial-state configuration using the Bose-Hubbard Hamiltonian an exact quantum solution is available for this system in the case of few atoms and wells. One can also use it to test various approximate methods. Under the 2PI CTP scheme with this initial configuration, three different approximations are considered: (a) the Hartree-Fock-Bogoliubov (HFB) approximation (b) the next-to-leading-order 1/N expansion of the 2PI effective action up to second order in the interaction strength, and (c) a second-order perturbative expansion in the interaction strength. We present detailed comparisons between these approximations and determine their range of validity by contrasting them with the exact many-body solution for a moderate number of atoms and wells. As a general feature we observe that because the second-order 2PI approximations include multiparticle scattering in a systematic way, they are able to capture damping effects exhibited in the exact solution, which a mean-field collisionless approach fails to produce. While the second-order approximations show a clear improvement over the HFB approximation, our numerical results show that they fail at late times, when interaction effects are significant
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...
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...
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.
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)
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.
Controlled polarization of two-dimensional quantum turbulence in atomic Bose-Einstein condensates
Cidrim, A.; dos Santos, F. E. A.; Galantucci, L.; Bagnato, V. S.; Barenghi, C. F.
2016-03-01
We propose a scheme for generating two-dimensional turbulence in harmonically trapped atomic condensates with the novelty of controlling the polarization (net rotation) of the turbulence. Our scheme is based on an initial giant (multicharged) vortex which induces a large-scale circular flow. Two thin obstacles, created by blue-detuned laser beams, speed up the decay of the giant vortex into many singly quantized vortices of the same circulation; at the same time, vortex-antivortex pairs are created by the decaying circular flow past the obstacles. Rotation of the obstacles against the circular flow controls the relative proportion of positive and negative vortices, from the limit of strongly anisotropic turbulence (almost all vortices having the same sign) to that of isotropic turbulence (equal number of vortices and antivortices). Using this scheme, we numerically study the decay of two-dimensional quantum turbulence as a function of the polarization. Finally, we present a model for the decay rate of the vortex number which fits our numerical experiment curves, with the novelty of taking into account polarization time dependence.
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
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.
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.
Understanding Hawking radiation from simple models of atomic Bose-Einstein condensates
Balbinot, R; Fabbri, A; Mayoral, C; Recati, A
2012-01-01
This chapter is an introduction to the Bogoliubov theory of dilute Bose condensates as applied to the study of the spontaneous emission of phonons in a stationary condensate flowing at supersonic speeds. This emission process is a condensed-matter analog of Hawking radiation from astrophysical black holes but is derived here from a microscopic quantum theory of the condensate without any use of the analogy with gravitational systems. To facilitate physical understanding of the basic concepts, a simple one-dimensional geometry with a stepwise homogenous flow is considered which allows for a fully analytical treatment.
Atom interferometry using Bose-Einstein condensates on Earth and in space
Sackett, C. A.; Leonard, R. H.; Fallon, A.
2015-03-01
The Cold Atom Laboratory is a multipurpose ultracold gas experiment currently being developed for operation on the international space station. It will have the ability to demonstrate proof-of-principle atom interferometry experiments in space. By using microgravity, atom interferometry has the potential to achieve extremely good performance in sensing and navigation applications. Terrestrial experiments can be used to explore potential challenges and prior to launch. One issue of concern is the release of cold atoms from a magnetic trap into free space. Although the atoms will not fall, they can acquire relatively large velocities due to technical limitations such as stray magnetic fields. This can limit the time available for measurements and thus the atom interferometer performance.
Atom laser based on four-wave mixing with Bose-Einstein condensates in nonlinear lattices
Wasak, T.; Konotop, V. V.; Trippenbach, M.
2013-12-01
Optical lattices are typically used to modify the dispersion relation of the matter wave, in particular, to ensure resonant conditions for multiwave interactions. Here we propose an alternative mechanism of wave interactions. It can be implemented using a nonlinear lattice and modifies the momentum conservation law of the interacting atoms, leaving the energy conservation unchanged. We propose to apply this phenomenon to construct an atom laser via a resonant four-wave mixing process.
Atom-chip based quantum gravimetry with Bose-Einstein condensates
Abend, Sven; Gersemann, Matthias; Ahlers, Holger; Rasel, Ernst M.; Gebbe, Martina; Muentinga, Hauke; Laemmerzahl, Claus; Quantus Team
2015-05-01
Today's generation of inertial sensitive atom interferometers typically operate with sources of laser cooled atoms and thus their performance is limited by velocity spread and finite-size effects that impose systematic uncertainties. Ultra-cold sources such as a BEC or even delta-kick cooled atomic ensembles with extremely narrow velocity dispersion are able to overcome these limitations and are crucial for obtaining high-fidelity beam splitters. Atom-chip technologies offer the possibility to generate a BEC and perform delta-kick cooling in a fast and reliable away. We show a combination of such an ensemble generated in a miniaturized atom-chip setup with the application of low-loss Bragg beam splitting to perform inertial sensitive measurements. A specialty of this setup is the retro-reflection of the beam splitting light field from the atom-chip itself, serving as inertial reference in vacuum. This allows for a compact realization of a quantum gravimeter determining the local gravitational acceleration to the scale of local variations limited by seismic noise. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50 1131-1137 (QUANTUS-III).
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.
Local-field effect in atom optics of two-component Bose-Einstein condensates
K.V.Krutitsky; Marzlin, K. -P.; Audretsch, J.
2000-01-01
Starting from the first principles of nonrelativistic QED we have developed the quantum theory of the interaction of a two-component ultracold atomic ensemble with the electromagnetic field of vacuum and laser photons. The main attention has been paid to the consistent consideration of dynamical dipole-dipole interactions in the radiation field. Taking into account local-field effects we have derived the system of Maxwell-Bloch equations. Optical properties of the two-component Bose gas are i...
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.
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
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
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.
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.
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
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...
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.
Institute of Scientific and Technical Information of China (English)
印建平; 高伟建; 王海峰; 龙全; 王育竹
2002-01-01
We report on a new experimental result to generate dark hollow beams by using a geometric optical method.We propose two new methods to produce focused and localized hollow laser beams by using π-phase plates. UsingMonte-Carlo simulations, we have studied the Sisyphus cooling of alkali atoms in pyramidal hollow beam gravito-opticaltraps. We discuss some potential applications of the dark hollow beams in atom optics and the preparation of an alloptically-cooled and optically-trapped atomic Bose-Einstein condensation (BEC).Our research shows that an ultracoldatomic sample with a temperature of ～ 2μK can be obtained in the pyramidal hollow beam dipole trap and an alloptical-type BEC may be realized in a far blue-detuned, hollow beam trap.
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.
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.
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...
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
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.
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.
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.
Bright soliton trains of trapped Bose-Einstein condensates
Al Khawaja, U.; Stoof, H. T. C.; Hulet, R. G.; Strecker, K.E.; Patridge, G.B.
2002-01-01
We variationally determine the dynamics of bright soliton trains composed of harmonically trapped Bose-Einstein condensates with attractive interatomic interactions. In particular, we obtain the interaction potential between two solitons. We also discuss the formation of soliton trains due to the quantum mechanical phase fluctuations of a one-dimensional condensate.
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.
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.
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.
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.
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
Tunable Bistability in Hybrid Bose-Einstein Condensate Optomechanics
Yasir, Kashif Ammar
2015-01-01
Cavity-optomechanics, a rapidly developing area of research, has made a remarkable progress. A stunning manifestation of optomechanical phenomena is in exploiting the mechanical effects of light to couple the optical degree of freedom with mechanical degree of freedom. In this report, we investigate the controlled bistable dynamics of such hybrid optomechanical system composed of cigar-shaped Bose-Einstein condensate (BEC) trapped inside high-finesse optical cavity with one moving-end mirror and is driven by a single mode optical field. The numerical results provide evidence for controlled optical bistability in optomechanics using transverse optical field which directly interacts with atoms causing the coupling of transverse field with momentum side modes, exited by intra-cavity field. This technique of transverse field coupling is also used to control bistable dynamics of both moving-end mirror and BEC. The report provides an understanding of temporal dynamics of moving-end mirror and BEC with respect to tr...
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.
Vortons in two component Bose-Einstein condensates
International Nuclear Information System (INIS)
Ever since Witten's paper on superconducting cosmic strings, there has been an interest in strings with a non-trivial core structure. In particular, it is believed that such strings can form loops, known as vortons, which are stabilized against shrinking by current and charge trapped on the string world-sheet. In this paper, we show that analogous non-trivial vortices and stable vortex loops exist in non-relativistic two-component atomic Bose-Einstein condensates. In contrast with well-studied superfluid 4He, where similar vortex rings can be stable due to Magnus force only if they move, the vortex rings in two-component BECs can be stable even if they are at rest. We speculate that such vortons may have been already observed in the laboratory. Thus, it may be possible to test predictions regarding vortons in cosmology and astrophysics by doing controlled experiments in two-component BECs. (author)
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
Gravity, Bose-Einstein Condensates and Gross-Pitaevskii Equation
Gupta, Patrick Das
2015-01-01
We explore the effect of mutual gravitational interaction between ultra-cold gas atoms on the dynamics of Bose-Einstein condensates (BEC). Small amplitude oscillation of BEC is studied by applying variational technique to reduce the Gross-Pitaevskii equation, with gravity included, to the equation of motion of a particle moving in a potential. According to our analysis, if the s-wave scattering length can be tuned to zero using Feshbach resonance for future BEC with occupation numbers as high as $\\approx 10^{20}$, there exists a critical ground state occupation number above which the BEC is unstable, provided that its constituents interact with a $1/r^3 $ gravity at short scales.
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.
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...
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...
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.
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.
Squeezing and temperature measurement in Bose-Einstein Condensates
Rogel-Salazar, J.; Choi, S.; New, G. H. C.; Burnett, K.
2003-01-01
In this paper we discuss the presence of temperature-dependent squeezing in the collective excitations of trapped Bose-Einstein condensates, based on a recent theory of quasiparticle damping. A new scheme to measure temperature below the critical temperature is also considered.
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.
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.
'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.
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...
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...
Momentum state engineering and control in Bose-Einstein condensates
Potting, S.; M. Cramer; Meystre, P.
2001-01-01
We demonstrate theoretically the use of genetic learning algorithms to coherently control the dynamics of a Bose-Einstein condensate. We consider specifically the situation of a condensate in an optical lattice formed by two counterpropagating laser beams. The frequency detuning between the lasers acts as a control parameter that can be used to precisely manipulate the condensate even in the presence of a significant mean-field energy. We illustrate this procedure in the coherent acceleration...
Casimir force on an interacting Bose-Einstein condensate
Energy Technology Data Exchange (ETDEWEB)
Biswas, Shyamal; Majumder, Dwipesh; Saha, Kush [Department of Theoretical Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Bhattacharjee, J K [S.N. Bose National Centre for Basic Sciences, Sector 3, JD Block, Salt Lake, Kolkata 700098 (India); Chakravarty, Nabajit, E-mail: tpsb2@iacs.res.i [Positional Astronomy Centre, Block AQ, Plot 8, Sector 5, Salt Lake, Kolkata 700091 (India)
2010-04-28
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wavefunction as well as for the phonon field. We have shown that the condensate wavefunction (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of the Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
Casimir force on interacting Bose-Einstein condensate
Biswas, Shyamal; Bhattacharjee, J K; Majumder, Dwipesh; Saha, Kush; Chakravarty, Nabajit
2009-01-01
We have presented an analytic theory for the Casimir force on a Bose-Einstein condensate (BEC) which is confined between two parallel plates. We have considered Dirichlet boundary conditions for the condensate wave function as well as for the phonon field. We have shown that, the condensate wave function (which obeys the Gross-Pitaevskii equation) is responsible for the mean field part of Casimir force, which usually dominates over the quantum (fluctuations) part of the Casimir force.
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.
Inhomogeneities and instabilities of Bose-Einstein condensates in rough potential landscapes
Shearring, Joe
2013-01-01
In this work we investigate the dynamics of Bose-Einstein condensates (BECs) in inhomogeneous potential landscapes. As this research field continues to develop, more attention will focus on non-equilibrium systems, on potential applications that use condensates, and on the integration of cold atoms with other physical systems. This thesis covers all of these areas. We begin by recapping the historical background of condensate physics, with a definition of the condensed phase and discussion...
Bose-Einstein Condensation in a Tightly Confining dc Magnetic Trap
Energy Technology Data Exchange (ETDEWEB)
Mewes, M.; Andrews, M.R.; van Druten, N.J.; Kurn, D.M.; Durfee, D.S.; Ketterle, W. [Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
1996-07-01
Bose-Einstein condensation of sodium atoms has been observed in a novel {open_quote}{open_quote}cloverleaf{close_quote}{close_quote} trap. This trap combines tight confinement with excellent optical access, using only dc electromagnets. Evaporative cooling in this trap produced condensates of 5{times}10{sup 6} atoms, a tenfold improvement over previous results. We measured the condensate fraction and the repulsive mean-field energy, finding agreement with theoretical predictions. {copyright} {ital 1996 The American Physical Society.}
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.
Vortex Nucleation in a Stirred Bose-Einstein Condensate
Raman, C.; Abo-Shaeer, J. R.; Vogels, J. M.; Xu, K.; Ketterle, W.
2001-01-01
We studied the nucleation of vortices in a Bose-Einstein condensate stirred by a laser beam. We observed the vortex cores using time-of-flight absorption imaging. By varying the size of the stirrer, we observed either discrete resonances or a broad response as a function of the frequency of the stirrer's motion. Stirring beams small compared to the condensate size generated vortices below the critical rotation frequency for the nucleation of surface modes, suggesting a local mechanism of gene...
Observation of Faraday Waves in a Bose-Einstein Condensate
Engels, P.; Atherton, C.; Hoefer, M. A.
2007-01-01
Faraday waves in a cigar-shaped Bose-Einstein condensate are created. It is shown that periodically modulating the transverse confinement, and thus the nonlinear interactions in the BEC, excites small amplitude longitudinal oscillations through a parametric resonance. It is also demonstrated that even without the presence of a continuous drive, an initial transverse breathing mode excitation of the condensate leads to spontaneous pattern formation in the longitudinal direction. Finally, the e...
Photon-photon gates in Bose-Einstein condensates
Rispe, Arnaud; He, Bing; Simon, Christoph
2010-01-01
It has recently been shown that light can be stored in Bose-Einstein condensates for over a second. Here we propose a method for realizing a controlled phase gate between two stored photons. The photons are both stored in the ground state of the effective trapping potential inside the condensate. The collision-induced interaction is enhanced by adiabatically increasing the trapping frequency and by using a Feshbach resonance. A controlled phase shift of $\\pi$ can be achieved in one second.
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.
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 $Z_2$...
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 ...
Anisotropic Bose-Einstein condensates and completely integrable dynamical systems
International Nuclear Information System (INIS)
A Gaussian ansatz for the wave function of two-dimensional harmonically trapped anisotropic Bose-Einstein condensates is shown to lead, via a variational procedure, to a coupled system of two second-order, nonlinear ordinary differential equations. This dynamical system is shown to be in the general class of Ermakov systems. Complete integrability of the resulting Ermakov system is proven. Using the exact solution, collapse of the condensate is analyzed in detail. Time dependence of the trapping potential is allowed
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
Bose-Einstein condensation for general dispersion relations
International Nuclear Information System (INIS)
Bose-Einstein condensation in an ideal (i.e. interactionless) boson gas can be studied analytically, at university-level statistical and solid state physics, in any positive dimensionality (d>0) for identical bosons with any positive-exponent (s>0) energy-momentum (i.e. dispersion) relation. Explicit formulae with arbitrary d/s are discussed for: the critical temperature (non-zero only if d/s>1); the condensate fraction; the internal energy; and the constant-volume specific heat (found to possess a jump discontinuity only if d/s>2). Classical results are recovered at sufficiently high temperatures. Applications to 'ordinary' Bose-Einstein condensation, as well as to photons, phonons, ferro- and antiferromagnetic magnons, and (very specially) to Cooper pairs in superconductivity, are mentioned. (author)
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.
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...
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.
Interferometry with independently prepared Bose-Einstein condensates
Wasak, T.; Szańkowski, P.; Chwedeńczuk, J.
2015-04-01
Whenever the value of an unknown parameter θ is extracted from a series of experiments, the result is inevitably burdened by the uncertainty Δ θ . If the system that is the subject of measurement consists of unentangled particles, this uncertainty is bounded by the shot-noise limit. To overcome this limitation, it is necessary to use a properly entangled state, which is usually prepared in a dedicated procedure. We show that quantum correlations arising from the indistinguishability of bosons are a sufficient resource for the sub-shot-noise interferometry. To this end, we consider an interferometer, which operates on two independently prepared Bose-Einstein condensates with fluctuating numbers of particles. We calculate the sensitivity obtained from the measurement of the number of atoms and compare it with the ultimate achievable bound. Our main conclusion is that even in the presence of major atom number fluctuations, an interferometer operating on two independently prepared condensates can give very high precision. These observations indicate a new possibility for an interferometer operating below the shot-noise limit.
Dynamics of bright matter-wave solitons in inhomogeneous cigar-type Bose-Einstein condensate
Abdullaev, F. Kh.; Gammal, A.; Tomio, L.
2002-01-01
We discuss the possible observation of a new type of standing nonlinear atomic matter wave in the condensate: the nonlinear impurity mode. It is investigated dynamical effects of a bright soliton in Bose-Einstein-condensed (BEC) systems with local space variations of the two-body atomic scattering length. A rich dynamics is observed in the interaction between the soliton and an inhomogeneity. Processes as trapping, reflection and transmission of the bright matter soliton due to the impurity a...
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
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.
Relaxation rates and collision integrals for Bose-Einstein condensates
Gust, Erich D.; Reichl, L. E.
2012-01-01
Near equilibrium, the rate of relaxation to equilibrium and the transport properties of excitations (bogolons) in a dilute Bose-Einstein condensate (BEC) are determined by three collision integrals, $\\mathcal{G}^{12}$, $\\mathcal{G}^{22}$, and $\\mathcal{G}^{31}$. All three collision integrals conserve momentum and energy during bogolon collisions, but only $ \\mathcal{G}^{22}$ conserves bogolon number. Previous works have considered the contribution of only two collision integrals, $ \\mathcal{G...
Spin turbulence in spinor Bose-Einstein condensates
Tsubota, Makoto; Fujimoto, Kazuya
2013-01-01
We summarize the recent theoretical and numerical works on spin turbulence (ST) in spin-1 spinor Bose-Einstein condensates. When the system is excited from the ground state, it goes through hy- drodynamic instability to ST in which the spin density vector has various disordered direction. The properties of ST depend on whether the spin-dependent interaction is ferromagnetic or antiferro- magnetic. ST has some characteristics different from other kinds of turbulence in quantum fluids. Firstly,...
Tunable Bistability in Hybrid Bose-Einstein Condensate Optomechanics
Kashif Ammar Yasir; Wu-Ming Liu
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 ...
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.
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
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...
Spin-Mixing Interferometry with Bose-Einstein Condensates.
Gabbrielli, Marco; Pezzè, Luca; Smerzi, Augusto
2015-10-16
Unstable spinor Bose-Einstein condensates are ideal candidates to create nonlinear three-mode interferometers. Our analysis goes beyond the standard SU(1,1) parametric approach and therefore provides the regime of parameters where sub-shot-noise sensitivities can be reached with respect to the input total average number of particles. Decoherence due to particle losses and finite detection efficiency are also considered. PMID:26550872
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...
Bose-Einstein Condensation of Dark Matter Axions
Sikivie, P.; Yang, Q.
2009-01-01
We show that cold dark matter axions thermalize and form a Bose-Einstein condensate. We obtain the axion state in a homogeneous and isotropic universe, and derive the equations governing small axion perturbations. Because they form a BEC, axions differ from ordinary cold dark matter in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microw...
Bose-Einstein Condensation in an electro-pneumatically transformed quadrupole-Ioffe magnetic trap
Kumar, Sunil; Verma, Gunjan; Vishwakarma, Chetan; Noaman, Md; Rapol, Umakant
2014-01-01
We report a novel approach for preparing a Bose-Einstein condensate (BEC) of $^{87}$Rb atoms using electro-pneumatically driven transfer of atoms into a Quadrupole-Ioffe magnetic trap (QUIC Trap). More than 5$\\times$$10^{8}$ atoms from a Magneto-optical trap are loaded into a spherical quadrupole trap and then these atoms are transferred into an Ioffe trap by moving the Ioffe coil towards the center of the quadrupole coil, thereby, changing the distance between quadrupole trap center and the Ioffe coil. The transfer efficiency is more than 80 \\%. This approach is different from a conventional approach of loading the atoms into a QUIC trap wherein the spherical quadrupole trap is transformed into a QUIC trap by changing the currents in the quadrupole and the Ioffe coils. The phase space density is then increased by forced rf evaporative cooling to achieve the Bose-Einstein condensation having more than $10^{5}$ atoms.
Berman, Oleg L; Kezerashvili, Roman Ya; Kolmakov, German V; Pomirchi, Leonid M
2015-06-01
The Bose-stimulated self-organization of a quasi-two-dimensional nonequilibrium Bose-Einstein condensate in an in-plane potential is proposed. We obtained the solution of the nonlinear, driven-dissipative Gross-Pitaevskii equation for a Bose-Einstein condensate trapped in an external asymmetric parabolic potential within the method of the spectral expansion. We found that, in sharp contrast to previous observations, the condensate can spontaneously acquire a solitonlike shape for spatially homogeneous pumping. This condensate soliton performs oscillatory motion in a parabolic trap and, also, can spontaneously rotate. Stability of the condensate soliton in the spatially asymmetric trap is analyzed. In addition to the nonlinear dynamics of nonequilibrium Bose-Einstein condensates of ultracold atoms, our findings can be applied to the condensates of quantum well excitons and cavity polaritons in semiconductor heterostructure, and to the condensates of photons. PMID:26172766
Berman, Oleg L.; Kezerashvili, Roman Ya.; Kolmakov, German V.; Pomirchi, Leonid M.
2015-06-01
The Bose-stimulated self-organization of a quasi-two-dimensional nonequilibrium Bose-Einstein condensate in an in-plane potential is proposed. We obtained the solution of the nonlinear, driven-dissipative Gross-Pitaevskii equation for a Bose-Einstein condensate trapped in an external asymmetric parabolic potential within the method of the spectral expansion. We found that, in sharp contrast to previous observations, the condensate can spontaneously acquire a solitonlike shape for spatially homogeneous pumping. This condensate soliton performs oscillatory motion in a parabolic trap and, also, can spontaneously rotate. Stability of the condensate soliton in the spatially asymmetric trap is analyzed. In addition to the nonlinear dynamics of nonequilibrium Bose-Einstein condensates of ultracold atoms, our findings can be applied to the condensates of quantum well excitons and cavity polaritons in semiconductor heterostructure, and to the condensates of photons.
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.
A molecular Bose-Einstein condensate emerges from a Fermi sea
Greiner, Markus; Regal, Cindy A.; Jin, Deborah S.
2003-01-01
The realization of fermionic superfluidity in a dilute gas of atoms, analogous to superconductivity in metals, is a long-standing goal of ultracold gas research. Beyond being a new example of this fascinating quantum phenomenon, fermionic superfluidity in an atomic gas holds the promise of adjustable interactions and the ability to tune continuously from BCS-type superfluidity to Bose-Einstein condensation (BEC). This crossover between BCS superfluidity of correlated atom pairs in momentum sp...
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.