Dynamics of Bose-Einstein Condensed and Excited Atoms in a Quantized Cavity

The dynamics of the Bose-Einstein condensed and excited atoms in a cavity interacting with quantized electromagnetic field of single mode is studied for both the cases with and without dissipation. It is shown that the frequencies of oscillation between the condensed atomic state and an excited state are related to the number of Bose-Einstein condensed atom in a certain form. This relation may be used for the reliable detection of the appearance of the Bose-Einstein condensate.     

Regular and Chaotic Spatial Distribution of Bose-Einstein Condensed Atoms in a Ratchet Potential

We study the regular and chaotic spatial distribution of Bose-Einstein condensed atoms with a space-dependent nonlinear interaction in a ratchet potential. There exists in the system a space-dependent atomic current that can be tuned via Feshbach resonance technique. In the presence of the space-dependent atomic current and a weak ratchet potential, the Smale-horseshoe chaos is studied and the Melnikov chaotic criterion is obtained. Numerical simulations show that the ratio between the intensities of optical potentials forming the ratchet potential, the wave vector of the laser producing the ratchet potential or the wave vector of the modulating laser can be chosen as the controlling parameters to result in or avoid chaotic spatial distributional states.     

Chaotic Ratchet Effect for Bose-Einstein Condensed Atoms in 1D Optical Lattices

The chaotic ratchet effect for Bose-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.     

Chaotic Ratchet Effect for Bose-Einstein Condensed Atoms in 1D Optical Lattices

The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.     

Magnetic Resonance Frequency Shift of Na Atoms during Collisions in a Mixture of Potassium and Sodium Atoms

Technical Physics - Collisions between sodium and potassium atom in the conditions of optical orientation of potassium atoms are considered. Because of collisions, the spin exchange occurs between...     

Laser Pumping of Alkali Atoms in Conditions of Conservation of the Nuclear Spin State in Collisions in a Gas Cell

Journal of Experimental and Theoretical Physics - We analyze the polarization of the total angular momentum of alkali atoms in a gas cell with a buffer gas under pumping by monofrequency circularly...     

Vector Solitons and Soliton Collisions in Two-Component Bose-Einstein Condensates

With realistic parameters, both analytical and computational studies demonstrate the feasibility of forming bright-bright vector solitons in a self-repulsive two-component Bose-Einstein condensate with attractive intercomponent interaction. Moreover, the stability of such solitons is confirmed by direct numerical simulations, by a Bogoliubov spectrum analysis, and by examining the collisions between two vector solitons. Our results are of considerable experimental interest.     

Partial Wave Cross Sections for Collisions between Helium Atoms and Hydrogen Halide Molecules

The close-coupling method is utilized to calculate partial cross sections for elastic and inelastic scattering of He atoms with HX （X=F, Cl, Br） molecule based on the CCSD （T） potential energy surfaces obtained in the previous research. The calculation is performed at the incident energy of 200 me V. The rationality of our results has been confirmed by comparison with the available theoretical results. The tendency of the elastic and inelastic rotational excitation partial wave cross sections varying with the reduced mass of the three systems is obtained.     

Quantum Light Excitation of Atoms in Ideal Bose-Einstein condensate

The spectrum shape of atomic radiation in the case of ideal Bose-Einstein condensate (BEC)excited by quantized light is derived through the Wigner-Weisskopf approximation. Besides the split and gap in the excitation spectrum, a doublet structure appears in the emission spectrum with different widths for the non-resonant case and the same widths for the resonant case. The survival probability is found to decrease exponentially for the non-resonan t case and with oscillation for the resonant case. A suppressed radiation also appears in the nonresonant case. All these results can be used to detect the existence of BE condensation.     

Quantum Correlation of Many Atoms in Spinor Bose-Einstein Condensates

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.     

Collisions of solitons and vortex rings in cylindrical Bose-Einstein condensates

Interactions of solitary waves in a cylindrically confined Bose-Einstein condensate are investigated by simulating their head-on collisions. Slow vortex rings and fast solitons are found to collide elastically contrary to the situation in the three-dimensional homogeneous Bose gas. Strongly inelastic collisions are absent for low density condensates but occur at higher densities for intermediate velocities. The scattering behavior is rationalized by use of dispersion diagrams. During inelastic collisions, spherical shell-like structures of low density are formed and they eventually decay into depletion droplets with solitary-wave features. The relation to similar shells observed in a recent experiment by Ginsberg et al. [Phys. Rev. Lett. 94, 040403 (2005)] is discussed.     

Spin-Flip and Elastic Processes in Slow Collisions of Mesic Atoms

The reduced adiabatic hyperspherical (RAHS) basis suggested previously is used for the calculation of elastic and spin-flip cross sections in the processes (aμ) _F + a → (aμ) _F′ + a, a = (p, d, t), for collision energies 10⁻³ ≤ ε ≤ 10² eV. The rapid convergence of the method is demonstrated. A comparison of the obtained results with previous ones is presented. This revised version was published online in August 2006 with corrections to the Cover Date.     

Atoms and molecules in lattices: Bose-Einstein condensates built on a shared vacuum

In optical lattices where each site is occupied in its lowest energy state by a superposition of zero, one, and two atoms, one can in a controllable manner convert the atomic pair into a molecule while retaining the vacuum and one-atom amplitudes. The microscopic quantum coherence on each site between the vacuum and the single molecule component leads to a macroscopically populated molecular condensate when the lattice is removed.     

Energy Losses in Collisions of Relativistic Structural Heavy Ions with Atoms

A nonperturbative theory of the energy losses in collisions of structural multiply charged heavy ions moving with relativistic velocities with atoms is worked out. Within the framework of this theory, by structural ions are meant ions containing partially filled electronic shells. It is such ions, having, as a rule, a considerable charge (for example, completely or partially stripped ions of uranium), that are used in many modern experiments on accelerators of heavy ions.     

Ultra-High Efficiency Magnetic Transport of SZRb Atoms in a Single Chamber Bose-Einstein Condensation Apparatus

We report the ultra-high efficiency transport of cold ST Ftb atoms using a moving magnetic quadrupole potential generated by three overlapping pairs of fixed coils. The transfer etticiency is better than 97%, which is the highest ever reported to our knowledge. The temperature increase due to heating is less than IO #K when the initial cloud temperature is llO#K. Our setup is similar to the magnetic transferring belt design [Phys. ftev. A 63 （2001）031401（R）], although it is simpler because the push coil is not required. We use it to transport atoms away from a magneto-optical trap to very close to the wall of the glass cell, facilitating future experiments employing three-dimensional optical lattices, high resolution in-situ imaging, and magnetic Feshbach resonances.     

Impact Excitations of Hydrogen Atoms in Collisions with Protons and Antiprotons

The direct impact excitations of ground-state hydrogen atoms by protons and antiprotons are investigated by using an impact parameter treatment. The calculations are performed within the solution of the coupled differential equations arising from the one-center atomic-orbital close-coupling approach as well as the impact parameter version of the first and second Born approximations. We have considered calculations that allow couplings to the n=1-5 states （up to g sub-levels） of the target atom as well as others, which neglect the effect of all states other than the initial and final states of the target atom. The sensitivity of the cross sections to the charge of the projectile is studied. The calculated cross sections are compared with those obtained by previous theoretical and experimental results.     

Collisions with Participation of Polarized Cesium and Lithium Alkali Atoms

Optics and Spectroscopy - The spin-exchange cross sections and the magnetic resonance frequency shift in collision of lithium and cesium atoms in the ground state are calculated. The calculations...