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Eric Heller
QUANTUM REFLECTION
AND OTHER TOPICS
Personnel: theoretical: E.J. Heller and John Doyle (co-PI's),
Diego Vaz Bevilaqa (postdoc), Stefan Filipov, Jian Huang,
Sheng Li, Areez Mody, Robert Parrott, Jay Vaishnav,
Jiri Vanicek (graduate students)
Our main results concern Sheng Li's work on multiple
scattering from ultracold atomic gasses. The scattering
theory includes both photon and particle cases, and
one of its advances is to clearly relate these two possibilities
for the first time. The theory applies to the situation
often associated with superradiance, in which the radiation
wavelength (or deBroglie scattering particle wavelength)
is large compared to the interparticle scattering, and
the particle or photon scattering is resonant with the
individual atoms. Several years ago we discovered the
phenomenon of proximity resonance, which is the particle
scattering version of this scenario. Essentially, the
individual atomic resonances are a basis, one for each
atom, which combine to give a variety of super-radiant
and subradiant resonances. We have found an optimal
'eigenchannel' basis to describe the scattering, and
one paper is published just recently [Sheng Li and E.J.
Heller, 'Quantum Multiple Scatttering: Eignemode Expansion
and Its Applications to Proximity Resonance', PRA, 67,
32712 (2003)] with another being written. This latter
paper describes the multiple resonant scattering for
particles and light, and relates the two. The relevance
for cold gases includes scattering particles or photons
(of long wavelength) from dense, cold atomic gasses.
We are addresssing the question of the residence time
of photons in the gas, the new efffective forces which
the photon induces, and the coherence of the evolution
of the scattering.
The latter question is connected to the nonadiabatic
interaction cased by the motion of the atoms, either
pre-existing motion or movement induced by dipole interactions
of resonant atoms with non-resonant ones. For example,
if a photon can induce a transition capable of causing
a high field seeking atom to become low field seeking,
it will fly from the trap if it is isolated. But if
this excited state character is quickly shared with
other nearby atoms (adiabatic limit) then it is possible
that no atom will be ejected form the trap. This scenario
is being investigated by Jay Vaishnav and Diego Vaz
Bevilaqua of our group.
Finally, we have begun new work with Mara Prentiss
suggesting new backscattering measures of coherence
in atom waveguides.
Related Publications
A. Mody, M. Haggerty, J. Doyle, and E. J. Heller, “The
no-sticking effect and quantum reflection in ultra-cold
collisions”
Phys. Rev. B, 64 085418
(2001).
D. V. Bevilaqua and E. J. Heller, “Fidelity Decay
for Phase Space Displacements”
arxiv.org/pdf/nlin.CD/0409007, (September 19, 2005)
A. Ruiz, E.J. Heller, “Quasiresonance”
arxiv.org/pdf/physics/050132, 19 May 2005
G. Fiete and E. J. Heller, “Semiclassical Theory
of Coherence and Decoherence”
Phys. Rev. A, 68,
022112 (2003).
J. Vanicek and E. J. Heller “Semiclassical evaluation
of quantum fidelity
Phys. Rev. E, 68,
056208 (2003).
J. Y. Vaishnav, A. Itsara, E. J. Heller, “Hall
of Mirrors Scattering from an Impurity in a Quantum
Wire”
Submitted to Phys. Rev. B, preprint available
at quant-ph/0511137.
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