2,408 research outputs found
Quantum effects in the collective light scattering by coherent atomic recoil in a Bose-Einstein condensate
We extend the semiclassical model of the collective atomic recoil laser
(CARL) to include the quantum mechanical description of the center-of-mass
motion of the atoms in a Bose-Einstein condensate (BEC). We show that when the
average atomic momentum is less than the recoil momentum , the
CARL equations reduce to the Maxwell-Bloch equations for two momentum levels.
In the conservative regime (no radiation losses), the quantum model depends on
a single collective parameter, , that can be interpreted as the average
number of photons scattered per atom in the classical limit. When ,
the semiclassical CARL regime is recovered, with many momentum levels populated
at saturation. On the contrary, when , the average momentum
oscillates between zero and , and a periodic train of
hyperbolic secant pulses is emitted. In the dissipative regime (large radiation
losses) and in a suitable quantum limit, a sequential superfluorescence
scattering occurs, in which after each process atoms emit a hyperbolic
secant pulse and populate a lower momentum state. These results describe the
regular arrangement of the momentum pattern observed in recent experiments of
superradiant Rayleigh scattering from a BEC.Comment: submitted for publication on Phys. Rev.
Atomic interaction effects in the superradiant light scattering from a Bose-Einstein condensate
We investigate the effects of the atomic interaction in the Superradiant
Rayleigh scattering from a Bose-Einstein condensate driven by a far-detuned
laser beam. We show that for a homogeneous atomic sample the atomic interaction
has only a dispersive effect, whereas in the inhomogeneous case it may increase
the decay of the matter-wave grating.Comment: 12 pages, 4 figures, presented to the XII International Laser Physics
Workshop, August 24-29, Hamburg, to be published in Laser Physic
Study of an auroral zone rocket experiment Final report
Measurement of flux and energy spectra of protons, energetic particles, hydrogen atoms, and electrons in auroral zone by Nike-Tomahawk sounding rocke
Effects of arcing due to spacecraft charging on spacecraft survival
A quantitative assessment of the hazard associated with spacecraft charging and arcing on spacecraft systems is presented. A literature survey on arc discharge thresholds and characteristics was done and gaps in the data and requirements for additional experiments were identified. Calculations of coupling of arc discharges into typical spacecraft systems were made and the susceptibility of typical spacecraft to disruption by arc discharges was investigated. Design guidelines and recommended practices to reduce or eliminate the threat of malfunction and failures due to spacecraft charging/arcing were summarized
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
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