2,107 research outputs found
The Semiclassical and Quantum Regimes of Superradiant Light Scattering from a Bose-Einstein Condensate
We show that many features of the recent experiments of Schneble et al. [D.
Schneble, Y. Torii, M. Boyd, E.W. Streed, D.E. Pritchard and W. Ketterle,
Science vol. 300, p. 475 (2003)], which demonstrate two different regimes of
light scattering by a Bose-Einstein condensate, can be described using a
one-dimensional mean-field quantum CARL model, where optical amplification
occurs simultaneously with the production of a periodic density modulation in
the atomic medium. The two regimes of light scattering observed in these
experiments, originally described as ``Kapiza-Dirac scattering'' and
``Superradiant Rayleigh scattering'', can be interpreted as the semiclassical
and quantum limits respectively of CARL lasing.Comment: 10 pages, 5 figures - to appear in Journal of Optics
Effects of atomic diffraction on the Collective Atomic Recoil Laser
We formulate a wave atom optics theory of the Collective Atomic Recoil Laser,
where the atomic center-of-mass motion is treated quantum mechanically. By
comparing the predictions of this theory with those of the ray atom optics
theory, which treats the center-of-mass motion classically, we show that for
the case of a far off-resonant pump laser the ray optics model fails to predict
the linear response of the CARL when the temperature is of the order of the
recoil temperature or less. This is due to the fact that in theis temperature
regime one can no longer ignore the effects of matter-wave diffraction on the
atomic center-of-mass motion.Comment: plain tex, 10 pages, 10 figure
Optical bistability in sideband output modes induced by squeezed vacuum
We consider two-level atoms in a ring cavity interacting with a broadband
squeezed vacuum centered at frequency and an input monochromatic
driving field at frequency . We show that, besides the central mode
(at \o), many other {\em sideband modes} are produced at the output, with
frequencies shifted from by multiples of .
Here we analyze the optical bistability of the two nearest sideband modes, one
red-shifted and the other blue-shifted.Comment: Replaced with final published versio
Teleportation improvement by inconclusive photon subtraction
Inconclusive photon subtraction (IPS) is a conditional measurement scheme to
force nonlinear evolution of a given state. In IPS the input state is mixed
with the vacuum in a beam splitter and then the reflected beam is revealed by
ON/OFF photodetection. When the detector clicks we have the (inconclusive)
photon subtracted state. We show that IPS on both channels of an entangled
twin-beam of radiation improves the fidelity of coherent state teleportation if
the energy of the incoming twin-beam is below a certain threshold, which
depends on the beam splitter transmissivity and the quantum efficiency of
photodetectors. We show that the energy threshold diverges when the
transmissivity and the efficiency approach unit and compare our results with
that of previous works on {\em conclusive} photon subtraction.Comment: slightly revised version, to appear in PR
Radiation to atom quantum mapping by collective recoil in Bose-Einstein condensate
We propose an experiment to realize radiation to atom continuous variable
quantum mapping, i.e. to teleport the quantum state of a single mode radiation
field onto the collective state of atoms with a given momentum out of a
Bose-Einstein condensate. The atoms-radiation entanglement needed for the
teleportation protocol is established through the interaction of a single mode
with the condensate in presence of a strong far off-resonant pump laser,
whereas the coherent atomic displacement is obtained by the same interaction
with the radiation in a classical coherent field. In principle, verification of
the protocol requires a joint measurement on the recoiling atoms and the
condensate, however, a partial verification involving populations, i.e.
diagonal matrix elements may be obtained through counting atoms experiments
- …