Very long storage times and evaporative cooling of cesium atoms in a quasi-electrostatic dipole trap

We have trapped cesium atoms over many minutes in the focus of a CO$_2$-laser beam employing an extremely simple laser system. Collisional properties of the unpolarized atoms in their electronic ground state are investigated. Inelastic binary collisions changing the hyperfine state lead to trap loss which is quantitatively analyzed. Elastic collisions result in evaporative cooling of the trapped gas from 25 $\mu$K to 10 $\mu$K over a time scale of about 150 s.Comment: 5 pages, 3 figure

Fictitious Magnetic Resonance by Quasi-Electrostatic Field

We propose a new kind of spin manipulation method using a {\it fictitious} magnetic field generated by a quasi-electrostatic field. The method can be applicable to every atom with electron spins and has distinct advantages of small photon scattering rate and local addressability. By using a $\rm{CO_2}$ laser as a quasi-electrostatic field, we have experimentally demonstrated the proposed method by observing the Rabi-oscillation of the ground state hyperfine spin F=1 of the cold $\rm{^{87}Rb}$ atoms and the Bose-Einstein condensate.Comment: 5 pages, 5 figure

Photoassociation of cold atoms with chirped laser pulses: time-dependent calculations and analysis of the adiabatic transfer within a two-state model

This theoretical paper presents numerical calculations for photoassociation of ultracold cesium atoms with a chirped laser pulse and detailed analysis of the results. In contrast with earlier work, the initial state is represented by a stationary continuum wavefunction. In the chosen example, it is shown that an important population transfer is achieved to $\approx 15$ vibrational levels in the vicinity of the v=98 bound level in the external well of the $0_g^-(6s+6p_{3/2})$ potential. Such levels lie in the energy range swept by the instantaneous frequency of the pulse, thus defining a ``photoassociation window''. Levels outside this window may be significantly excited during the pulse, but no population remains there after the pulse. Finally, the population transfer to the last vibrational levels of the ground $a^3\Sigma_u^+$(6s + 6s) is significant, making stable molecules. The results are interpreted in the framework of a two state model as an adiabatic inversion mechanism, efficient only within the photoassociation window. The large value found for the photoassociation rate suggests promising applications. The present chirp has been designed in view of creating a vibrational wavepacket in the excited state which is focussing at the barrier of the double well potential.Comment: 49 pages, 9 figures, submitted to Phys. Rev.

Quantum entanglement using trapped atomic spins

We propose an implementation for quantum logic and computing using trapped atomic spins of two different species, interacting via direct magnetic spin-spin interaction. In this scheme, the spins (electronic or nuclear) of distantly spaced trapped neutral atoms serve as the qubit arrays for quantum information processing and storage, and the controlled interaction between two spins, as required for universal quantum computing, is implemented in a three step process that involves state swapping with a movable auxiliary spin.Comment: minor revisions with an updated discussion on adibatic tranportation of trapped qubit, 5 pages, 3 figs, resubmitted to PR

Inhibitory Effects of Anti-VEGF Antibody on the Growth and Angiogenesis of Estrogen-induced Pituitary Prolactinoma in Fischer 344 Rats: Animal Model of VEGF-targeted Therapy for Human Endocrine Tumors

Estrogen-induced pituitary prolactin-producing tumors (PRLoma) in F344 rats express a high level of vascular endothelial growth factor (VEGF) associated with marked angiogenesis and angiectasis. To investigate whether tumor development in E2-induced PRLoma is inhibited by anti-VEGF monoclonal antibody (G6-31), we evaluated tumor growth and observed the vascular structures. With simultaneous treatment with G6-31 for the latter three weeks of the 13-week period of E2 stimulation (E2+G6-31 group), the following inhibitory effects on the PRLoma were observed in the E2+G6-31 group as compared with the E2-only group. In the E2+G6-31 group, a tendency to reduction in pituitary weight was observed and significant differences were observed as (1) reductions in the Ki-67-positive anterior cells, (2) increases in TUNEL-positive anterior cells, and (3) repair of the microvessel count by CD34-immunohistochemistry. The characteristic “blood lakes” in PRLomas were improved and replaced by repaired microvascular structures on 3D observation using confocal laser scanning microscope. These inhibitory effects due to anti-VEGF antibody might be related to the autocrine/paracrine action of VEGF on the tumor cells, because VEGF and its receptor are co-expressed on the tumor cells. Thus, our results demonstrate that anti-VEGF antibody exerted inhibitory effects on pituitary tumorigenesis in well-established E2 induced PRLomas

Suppression of inhomogeneous broadening in rf spectroscopy of optically trapped atoms

We present a novel method for reducing the inhomogeneous frequency broadening in the hyperfine splitting of the ground state of optically trapped atoms. This reduction is achieved by the addition of a weak light field, spatially mode-matched with the trapping field and whose frequency is tuned in-between the two hyperfine levels. We experimentally demonstrate the new scheme with Rb 85 atoms, and report a 50-fold narrowing of the rf spectrum

Combined ion and atom trap for low temperature ion-atom physics

We report an experimental apparatus and technique which simultaneously traps ions and cold atoms with spatial overlap. Such an apparatus is motivated by the study of ion-atom processes at temperatures ranging from hot to ultra-cold. This area is a largely unexplored domain of physics with cold trapped atoms. In this article we discuss the general design considerations for combining these two traps and present our experimental setup. The ion trap and atom traps are characterized independently of each other. The simultaneous operation of both is then described and experimental signatures of the effect of the ions and cold-atoms on each other are presented. In conclusion the use of such an instrument for several problems in physics and chemistry is briefly discussed.Comment: 24 pages, 13 figures. Figures Fixe