14,154 research outputs found
Bond Order via Light-Induced Synthetic Many-body Interactions of Ultracold Atoms in Optical Lattices
We show how bond order emerges due to light mediated synthetic interactions
in ultracold atoms in optical lattices in an optical cavity. This is a
consequence of the competition between both short- and long-range interactions
designed by choosing the optical geometry. Light induces effective many-body
interactions that modify the landscape of quantum phases supported by the
typical Bose-Hubbard model. Using exact diagonalization of small system sizes
in one dimension, we present the many-body quantum phases the system can
support via the interplay between the density and bond (or matter-wave
coherence) interactions. We find numerical evidence to support that dimer
phases due to bond order are analogous to valence bond states. Different
possibilities of light-induced atomic interactions are considered that go
beyond the typical atomic system with dipolar and other intrinsic interactions.
This will broaden the Hamiltonian toolbox available for quantum simulation of
condensed matter physics via atomic systems.Comment: Accepted in New Journal of Physic
ALICE experience with GEANT4
Since its release in 1999, the LHC experiments have been evaluating GEANT4 in
view of adopting it as a replacement for the obsolescent GEANT3 transport
MonteCarlo. The ALICE collaboration has decided to perform a detailed physics
validation of elementary hadronic processes against experimental data already
used in international benchmarks. In one test, proton interactions on different
nuclear targets have been simulated, and the distribution of outgoing particles
has been compared to data. In a second test, penetration of quasi-monoenergetic
low energy neutrons through a thick shielding has been simulated and again
compared to experimental data. In parallel, an effort has been put on the
integration of GEANT4 in the AliRoot framework. An overview of the present
status of ALICE GEANT4 simulation and the remaining problems will be presented.
This document will describe in detail the results of these tests, together with
the improvements that the GEANT4 team has made to the program as a result of
the feedback received from the ALICE collaboration. We will also describe the
remaining problems that have been communicated to GEANT4 but not yet addressed.Comment: 8 pages, 12 figures, for the CHEP03 conference proceeding
Phase diagram of Landau-Zener phenomena in coupled one-dimensional Bose quantum fluids
We study stationary and dynamical properties of the many-body Landau-Zener
dynamics of a Bose quantum fluid confined in two coupled one-dimensional
chains, using a many-body generalization recently reported [Y.-A. Chen et al.],
within the decoupling approximation and the one-level band scheme. The energy
spectrum evidences the structure of the avoided level crossings as a function
of the on-site inter particle interaction strength. On the dynamical side, a
phase diagram of the transfer efficiency across ground-state and inverse sweeps
is presented. A totally different scenario with respect to the original
single-particle Landau-Zener scheme is found for ground-state sweeps, in which
a breakdown of the adiabatic region emerges as the sweep rate decreases. On the
contrary, the transfer efficiency across inverse sweeps reveals consistent
results with the single-particle Landau-Zener predictions. In the strong
coupling regime, we find that there is a critical value of the on-site
interaction for which the transfer of particles starts to vanish independently
of the sweep rate. Our results are in qualitative agreement with those of the
experimental counterpart.Comment: 15 pages, submitted to Phys. Rev. A (new version
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