Search results for "CONDENSATE"

Allergen-specific Immunotherapy with Purified nAlt a1: Effects on AMP Responsiveness, Exhaled Nitric Oxide and Exhaled Breath Condensate pH

2010

Design of a compact diode laser system for dual-species atom interferometry with rubidium and potassium in space

2017

We report on a micro-integrated high power diode laser based system for the MAIUS II/III missions. The laser system features fiber coupled and frequency stabilized external cavity diode lasers (ECDL) for laser cooling, Bose-Einstein condensate (BEC) generation and dual species atom interferometry with rubidium and potassium on board a sounding rocket.

The effect of interactions on Bose-Einstein condensation in a quasi two-dimensional harmonic trap

1999

A dilute bose gas in a quasi two-dimensional harmonic trap and interacting with a repulsive two-body zero-range potential of fixed coupling constant is considered. Using the Thomas-Fermi method, it is shown to remain in the same uncondensed phase as the temperature is lowered. Its density profile and energy are identical to that of an ideal gas obeying the fractional exclusion statistics of Haldane. PACS: ~03.75.Fi, 05.30.Jp, 67.40.Db, 05.30.-d

Room temperature polariton luminescence from a GaN∕AlGaN quantum well microcavity

2006

The authors report on the demonstration of strong light-matter coupling at room temperature using a crack-free UV microcavity containing GaN/AlGaN quantum wells (QWs). Lattice-matched AlInN/AlGaN distributed Bragg reflectors (DBRs) with a maximum peak reflectivity of 99.5% and SiO2/Si3N4 DBRs were used to form high finesse hybrid microcavities. State-of-the-art GaN/Al0.2Ga0.8N QWs emitting at 3.62 eV with a linewidth of 45 meV at 300 K were inserted in these structures. For a 3 lambda/2 microcavity containing six QWs, the interaction between cavity photons and QW excitons is sufficiently large to reach the strong coupling regime. A polariton luminescence is observed with a vacuum field Rabi…

Vortices in rotating two-component boson and fermion traps

2010

Quantum liquids may carry angular momentum by the formation of vortex states. This is well known for Bose-Einstein condensates in rotating traps, and was even found to occur in quantum dots at strong magnetic fields. Here we consider a two-component quantum liquid, where coreless vortices and interlaced lattices of coreless vortices appear in a very similar way for fermions and bosons with repulsive two-body interactions. The ground states at given angular momentum, as well as the pair correlations for equal and different numbers of atoms in the two components, are studied. (C) 2009 Elsevier B.V. All rights reserved.

Weakly Interacting Bose-Einstein Condensates under Rotation: Mean-Field versus Exact Solutions

2000

We consider a weakly-interacting, harmonically-trapped Bose-Einstein condensed gas under rotation and investigate the connection between the energies obtained from mean-field calculations and from exact diagonalizations in a subspace of degenerate states. From the latter we derive an approximation scheme valid in the thermodynamic limit of many particles. Mean-field results are shown to emerge as the correct leading-order approximation to exact calculations in the same subspace.

Singularity formation in the Gross-Pitaevskii equation and collapse in Bose-Einstein condensates

2004

We study the mechanisms of collapse of the condensate wave function in the Gross-Pitaevskii theory with attractive interparticle interaction. We reformulate the Gross-Pitaevskii equation as Newton's equations for a flux of particles, and introduce the collapsing fraction of particles. We assume that this collapsing fraction is expelled from the condensate due to dissipation. Using this hypothesis we analyze the dependence of the collapse behavior on the initial conditions. We find that, for a properly chosen negative scattering length, the remnant fraction of atoms becomes larger when the initial aspect ratio of the condensate is increased.

Ultracold atoms in optical lattices

2007

This article focuses on the characteristics and properties ultracold atoms in optical lattices.

Experiments on the dynamics of the Bose–Einstein condensate at finite temperatures

2009

This paper presents the results of our recent experiments on the finite-temperature Bose?Einstein condensate of 87Rb atoms in a magnetic trap, and is devoted to the study of the hydrodynamic properties and dynamics of an ultra-cold atomic gas near the critical temperature. Measurements of the aspect ratio of an expanding atomic cloud allow for verification of the condensate models and study of the interaction between condensed and non-condensed fractions of a finite-temperature sample.

Roton-roton crossover in strongly correlated dipolar Bose-nonstnon condensates

2011

We study the pair correlations and excitations of a dipolar Bose gas layer. The anisotropy of the dipole-dipole interaction allows us to tune the strength of pair correlations from strong to weak perpendicular and weak to strong parallel to the layer by increasing the perpendicular trap frequency. This change is accompanied by a roton-roton crossover in the spectrum of collective excitations, from a roton caused by the head-to-tail attraction of dipoles to a roton caused by the side-by-side repulsion, while there is no roton excitation for intermediate trap frequencies. We discuss the nature of these two kinds of rotons and the relation to instabilities of dipolar Bose gases. In both regime…