2,562 research outputs found
Dimensional instability of aluminum alloys for extreme low temperature cycling applications /GGV material instability problem/
Dimensional instability of aluminum alloys during cryogenic thermal cyclin
Properties of large 7079 aluminum alloy forgings in a cryogenic environment
Forged aluminum alloys for pump impeller and inducer applications in cryogenic liquid propellant rocket engine
Application of Alloy 718 in M-1 engine components
Alloy 718 applied to components of M-1 rocket engin
Cross-Dimensional relaxation in Bose-Fermi mixtures
We consider the equilibration rate for fermions in Bose-Fermi mixtures
undergoing cross-dimensional rethermalization. Classical Monte Carlo
simulations of the relaxation process are performed over a wide range of
parameters, focusing on the effects of the mass difference between species and
the degree of initial departure from equilibrium. A simple analysis based on
Enskog's equation is developed and shown to be accurate over a variety of
different parameter regimes. This allows predictions for mixtures of commonly
used alkali atoms.Comment: 7 pages, 4 figures, uses Revtex 4. This is a companion paper to [PRA
70, 021601(R) (2004)] (cond-mat/0405419
Sequential superradiant scattering from atomic Bose-Einstein condensates
We theoretically discuss several aspects of sequential superradiant
scattering from atomic Bose-Einstein condensates. Our treatment is based on the
semiclassical description of the process in terms of the Maxwell-Schroedinger
equations for the coupled matter-wave and optical fields. First, we investigate
sequential scattering in the weak-pulse regime and work out the essential
mechanisms responsible for bringing about the characteristic fan-shaped
side-mode distribution patterns. Second, we discuss the transition between the
Kapitza-Dirac and Bragg regimes of sequential scattering in the strong-pulse
regime. Finally, we consider the situation where superradiance is initiated by
coherently populating an atomic side mode through Bragg diffraction, as in
studies of matter-wave amplification, and describe the effect on the sequential
scattering process.Comment: 9 pages, 4 figures. Submitted to Proceedings of LPHYS'06 worksho
Multiply quantized vortices in trapped Bose-Einstein condensates
Vortex configurations in rotating Bose-Einstein condensed gases trapped in
power-law and anharmonic potentials are studied. When the confining potential
is steeper than harmonic in the plane perpendicular to the axis of rotation,
vortices with quantum numbers larger than one are energetically favorable if
the interaction is weak enough. Features of the wave function for small and
intermediate rotation frequencies are investigated numerically.Comment: 9 pages, 6 figures. Revised and extended article following referee
repor
Experimental observation of the Bogoliubov transformation for a Bose-Einstein condensed gas
Phonons with wavevector were optically imprinted into a
Bose-Einstein condensate. Their momentum distribution was analyzed using Bragg
spectroscopy with a high momentum transfer. The wavefunction of the phonons was
shown to be a superposition of +q and -q free particle momentum states, in
agreement with the Bogoliubov quasiparticle picture.Comment: 4 pages, 3 figures, please take postscript version for the best
version of Fig
Bose-enhanced chemistry: Amplification of selectivity in the dissociation of molecular Bose-Einstein condensates
We study the photodissociation chemistry of a quantum degenerate gas of
bosonic triatomic molecules, assuming two open rearrangement channels
( or ). The equations of motion are equivalent to those of a
parametric multimode laser, resulting in an exponential buildup of macroscopic
mode populations. By exponentially amplifying a small differential in the
single-particle rate-coefficients, Bose stimulation leads to a nearly complete
selectivity of the collective -body process, indicating a novel type of
ultra-selective quantum degenerate chemistry.Comment: 5 pages, 3 figure
Optical microscopy via spectral modifications of a nano-antenna
The existing optical microscopes form an image by collecting photons emitted
from an object. Here we report on the experimental realization of microscopy
without the need for direct optical communication with the sample. To achieve
this, we have scanned a single gold nanoparticle acting as a nano-antenna in
the near field of a sample and have studied the modification of its intrinsic
radiative properties by monitoring its plasmon spectrum.Comment: 6 pages, 4 figures (color
Dynamic depletion in a Bose condensate via a sudden increase of the scattering length
We examine the time-dependent quantum depletion of a trapped Bose condensate
arising from a rapid increase of the scattering length. Our solution indicates
that a significant buildup of incoherent atoms can occur within a
characteristic time short compared with the harmonic trap period. We discuss
how the depletion density and the characteristic time depend on the physical
parameters of the condensate
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