Correlation functions for a Bose-Einstein condensate in the Bogoliubov approximation

In this article we introduce a differential equation for the first order correlation function G ⁽¹⁾ of a Bose-Einstein condensate at T = 0. The Bogoliubov approximation is used. Our approach points out directly the dependence on the physical parameters. Furthermore it suggests a numerical method to calculate G ⁽¹⁾ without solving an eigenvector problem. The G ⁽¹⁾ equation is generalized to the case of non zero temperature. Received 20 September 2000     

Tunneling control and localization for Bose-Einstein condensates in a frequency modulated optical lattice

The similarity between matter waves in periodic potential and solid-state physics processes has triggered the interest in quantum simulation using Bose-Fermi ultracold gases in optical lattices. The present work evidences the similarity between electrons moving under the application of oscillating electromagnetic fields and matter waves experiencing an optical lattice modulated by a frequency difference, equivalent to a spatially shaken periodic potential. We demonstrate that the tunneling properties of a Bose-Einstein condensate in shaken periodic potentials can be precisely controlled. We take additional crucial steps towards future applications of this method by proving that the strong shaking of the optical lattice preserves the coherence of the matter wavefunction and that the shaking parameters can be changed adiabatically, even in the presence of interactions. We induce reversibly the quantum phase transition to the Mott insulator in a driven periodic potential.     

External-cavity broad-area laser diode operating on the D(1) line of cesium

We present an external-cavity laser diode characterized by an intracavity cylinder lens to compensate for the astigmatism of the laser. This setup was applied to a broad-area laser diode operating on the D(1) line of the cesium atom at 894 nm, yielding single-mode emission. A saturated-absorption experiment on that atomic line tested the laser performance.     

Novel carbamate derivatives of 4-beta-amino-4'-O-demethyl-4-desoxypodophyllotoxin as inhibitors of topoisomerase II: synthesis and biological evaluation

A novel series of carbamate derivatives of 4-beta-amino-4'-O-demethyl-4-desoxypodophyllotoxin were synthesized. Their effect on human DNA topoisomerase II and antiproliferative activity was evaluated. Compounds 4a-c, 4g, 4j and 4k are topoisomerase II poisons that induce double-stranded breaks in DNA and exhibit increased cytotoxicity compared to etoposide.     

Diffraction pattern of atoms in a resonant standing wave laser field

We illustrate the diffraction pattern of an atomic beam for a resonant standing wave laser field, and stress its dependence on the angle of incidence. A maximum spread of the atomic beam is found to occur for an incidence angle close to, but different from normal incidence.     

Impurity analysis of gentamicin bulk samples by improved liquid chromatography-ion trap mass spectrometry

Several gentamicin bulk samples from different origins were investigated using an LC/MS method.LC equipped with ion trap MS with positive ionization was performed on a Capcell Pak C18(AQ) column with the mobile phase containing 50 mM trifluoroacetic(TFA) and methanol.Impurities present in batches of gentamicin bulk samples were elucidated and compared according to their fragmentation behavior.In total seventeen impurities present in samples,five impurities were not elucidated and two compounds were identifi...     

Cancellation of stark shifts in optical lattice clocks by use of pulsed Raman and electromagnetically induced transparency techniques

We propose a combination of electromagnetically induced transparency-Raman and pulsed spectroscopy techniques to accurately cancel frequency shifts arising from electromagnetically induced transparency fields in forbidden optical clock transitions of alkaline earth atoms. At appropriate detunings, time-separated laser pulses are designed to trap atoms in coherent superpositions while eliminating off-resonance ac Stark contributions, achieving efficient population transfer up to 60% with inaccuracy <10(-17). Results from the wave-function formalism are confirmed by the density matrix approach.     

Observation of photon-assisted tunneling in optical lattices

We have observed tunneling suppression and photon-assisted tunneling of Bose-Einstein condensates in an optical lattice subjected to a constant force plus a sinusoidal shaking. For a sufficiently large constant force, the ground energy levels of the lattice are shifted out of resonance and tunneling is suppressed; when the shaking is switched on, the levels are coupled by low-frequency photons and tunneling resumes. Our results agree well with theoretical predictions and demonstrate the usefulness of optical lattices for studying solid-state phenomena.