Trends in Resonance Energy Shifts and Decay Rates for Bose Condensates in a Harmonic Trap

This is a study of quasi-discrete Bogoliubov quasi-particles in a spherically symmetric harmonic trap. We first evaluate analytically the aymptotic energy shifts of the high energy modes and find them to have $1/sqrt(n)$ dependence on the number of radial nodes, $n$, consistent with earlier semiclassical discussions. To address the question of the widths or decay rates, we attempt to clarify previous discussions by deriving an implicit equation for the widths from an assumption of exponential decay. Numerically, we study the trends in the behavior of the widths as a function of temperature, energy, particle number and scattering lengths. In particular, we find that the width due to Landau decay rises rapidly at low $n$ and then declines, while the Beliaev decay rate rises slowly with $n$. As temperature goes to zero, Beliaev decay reaches a constant (>0 for n>0), while the Landau decay rate goes to zero. The decay rate is approximately linear in the s-wave scattering length.Comment: 10 figures. Accepted for publication in Physical Review

Hope as a Source of Resilience in Later Adulthood

This research provided a preliminary investigation of how variations in trait and state hope are associated with positive adaptation to stress in later adulthood. Trait hope and neuroticism were measured by questionnaires and state hope, stress, and negative emotions were assessed daily for 45 days. Results from multilevel random coefficient modeling analyses suggested that daily hope provides protective benefits by keeping negative emotions low, while also contributing to adaptive recovery from stress. The dynamic linkages between daily hope, stress, and emotion were further moderated by individual differences in trait hope. Compared with those low in trait hope, high-hope individuals showed diminished stress reactivity and more effective emotional recovery

Superfluid Bloch dynamics in an incommensurate lattice

We investigate the interplay of disorder and interactions in the accelerated transport of a Bose-Einstein condensate through an incommensurate optical lattice. We show that interactions can effectively cancel the damping of Bloch oscillations due to the disordered potential and we provide a simple model to qualitatively capture this screening effect. We find that the characteristic interaction energy, above which interactions and disorder cooperate to enhance, rather than reduce, the damping of Bloch oscillations, coincides with the average disorder depth. This is consistent with results of a mean-field simulation.Comment: 9 pages, 3 figure

Production and state-selective detection of ultracold, ground state RbCs molecules

Using resonance-enhanced two-photon ionization, we detect ultracold, ground-state RbCs molecules formed via photoassociation in a laser-cooled mixture of 85Rb and 133Cs atoms. We obtain extensive bound-bound excitation spectra of these molecules, which provide detailed information about their vibrational distribution, as well as spectroscopic data on the RbCs ground a^3\Sigma^+ and excited (2)^3\Sigma^+, (1)^1\Pi states. Analysis of this data allows us to predict strong transitions from observed excited levels to the absolute vibronic ground state of RbCs, potentially allowing the production of stable, ultracold polar molecules at rates as large as 10^7 s^{-1}

The angular momentum of a magnetically trapped atomic condensate

For an atomic condensate in an axially symmetric magnetic trap, the sum of the axial components of the orbital angular momentum and the hyperfine spin is conserved. Inside an Ioffe-Pritchard trap (IPT) whose magnetic field (B-field) is not axially symmetric, the difference of the two becomes surprisingly conserved. In this paper we investigate the relationship between the values of the sum/difference angular momentums for an atomic condensate inside a magnetic trap and the associated gauge potential induced by the adiabatic approximation. Our result provides significant new insight into the vorticity of magnetically trapped atomic quantum gases.Comment: 4 pages, 1 figure

Global Analysis of Data on the Spin-orbit-coupled A1Σ+ and b3Πu States of Cs2

We present experimentally derived potential curves and spin-orbit interaction functions for the strongly perturbed A1+ u and b3u states of the cesium dimer. The results are based on data from several sources. Laser-induced fluorescence Fourier transform spectroscopy (LIF FTS) was used some time ago in the Laboratoire Aim´e Cotton primarily to study the X1+ g state. More recent work at Tsinghua University provides information from moderate resolution spectroscopy on the lowest levels of the b3± 0u states as well as additional high resolution data. From Innsbruck University, we have precision data obtained with cold Cs2 molecules. Recent data from Temple University was obtained using the optical-optical double resonance polarization spectroscopy technique, and finally, a group at the University of Latvia has added additional LIF FTS data. In the Hamiltonian matrix, we have used analytic potentials (the Expanded Morse Oscillator form) with both finite-difference (FD) coupled-channels and discrete variable representation (DVR) calculations of the term values. Fitted diagonal and off-diagonal spin-orbit functions are obtained and compared with ab initio results from Temple and Moscow State universities

Atom-Atom Scattering Under Cylindrical Harmonic Confinement: Numerical and Analytical Studies of the Confinement Induced Resonance

In a recent article [M. Olshanii, Phys. Rev. Lett. {\bf 81}, 938 (1998)], an analytic solution of atom-atom scattering with a delta-function pseudopotential interaction in the presence of transverse harmonic confinement yielded an effective coupling constant that diverged at a `confinement induced resonance.' In the present work, we report numerical results that corroborate this resonance for more realistic model potentials. In addition, we extend the previous theoretical discussion to include two-atom bound states in the presence of transverse confinement, for which we also report numerical results hereComment: New version with major revisions. We now provide a detailed physical interpretation of the confinement-induced resonance in tight atomic waveguide

Electromagnetically induced transparency in an inverted Y-type four-level system

The interaction of a weak probe laser with an inverted-Y type four-level atomic system driven by two additional coherent fields is investigated theoretically. Under the influence of the coherent coupling fields, the steady-state linear susceptibility of the probe laser shows that the system can have single or double electromagnetically induced transparency windows depending on the amplitude and the detuning of the coupling lasers. The corresponding index of refraction associated with the group velocity of the probe laser can be controlled at both transparency windows by the coupling fields. The propagation of the probe field can be switched from superluminal near the resonance to subluminal on resonance within the single transparency window when two coupling lasers are on resonance. This provides a potential application in quantum information processing. We propose an atomic $^{87}Rb$ system for experimental observation