11 research outputs found
The Fermi accelerator in atom optics
We study the classical and quantum dynamics of a Fermi accelerator realized
by an atom bouncing off a modulated atomic mirror. We find that in a window of
the modulation amplitude dynamical localization occurs in both position and
momentum. A recent experiment [A. Steane, P. Szriftgiser, P. Desbiolles, and J.
Dalibard, Phys. Rev. Lett. {\bf 74}, 4972 (1995)] shows that this system can be
implemented experimentally.Comment: 5 pages, 5 figure
Thermodynamic properties of ferromagnetic mixed-spin chain systems
Using a combination of high-temperature series expansion, exact
diagonalization and quantum Monte Carlo, we perform a complementary analysis of
the thermodynamic properties of quasi-one-dimensional mixed-spin systems with
alternating magnetic moments. In addition to explicit series expansions for
small spin quantum numbers, we present an expansion that allows a direct
evaluation of the series coefficients as a function of spin quantum numbers.
Due to the presence of excitations of both acoustic and optical nature, the
specific heat of a mixed-spin chain displays a double-peak-like structure,
which is more pronounced for ferromagnetic than for antiferromagnetic
intra-chain exchange. We link these results to an analytically solvable
half-classical limit. Finally, we extend our series expansion to incorporate
the single-ion anisotropies relevant for the molecular mixed-spin ferromagnetic
chain material MnNi(NO)(ethylenediamine), with alternating
spins of magnitude 5/2 and 1. Including a weak inter-chain coupling, we show
that the observed susceptibility allows for an excellent fit, and the
extraction of microscopic exchange parameters.Comment: 8 pages including 7 figures, submitted to Phys. Rev. B; series
extended to 29th. QMC adde
Correlation functions for a laser with saturable absorber near threshold
SCOPUS: ar.jinfo:eu-repo/semantics/publishe