7,694 research outputs found
Tracking the evolution of multiple in vitro HCV replicon mutants under protease inhibitor selection pressure by 454 ultra deep sequencing.
Interference scheme to measure light-induced nonlinearities in Bose-Einstein condensates
Light-induced nonlinear terms in the Gross-Pitaevskii equation arise from the
stimulated coherent exchange of photons between two atoms. For atoms in an
optical dipole trap this effect depends on the spatial profile of the trapping
laser beam. Two different laser beams can induce the same trapping potential
but very different nonlinearities. We propose a scheme to measure light-induced
nonlinearities which is based on this observation.Comment: 2 figure
A Double-Mode RR Lyrae Star with a Strong Fundamental Mode Component
NSVS 5222076, a thirteenth magnitude star in the Northern Sky Variability
Survey, was identified by Oaster as a possible new double-mode RR Lyrae star.
We confirm the double-mode nature of NSVS 5222076, supplementing the survey
data with new V band photometry. NSVS 5222076 has a fundamental mode period of
0.4940 day and a first overtone period of 0.3668 day. Its fundamental mode
light curve has an amplitude twice as large as that of the first overtone mode,
a ratio very rarely seen. Data from the literature are used to discuss the
location in the Petersen diagram of double-mode RR Lyrae stars having strong
fundamental mode pulsation. Such stars tend to occur toward the short period
end of the Petersen diagram, and NSVS 5222976 is no exception to this rule.Comment: 14 pages, 4 figures, To be published in the March, 2006, issue of
PAS
Transverse QCD Dynamics Near the Light Cone
Starting from the QCD Hamiltonian in near-light cone coordinates, we study
the dynamics of the gluonic zero modes. Euclidean 2+1 dimensional lattice
simulations show that the gap at strong coupling vanishes at intermediate
coupling. This result opens the possibility to synchronize the continuum limit
with the approach to the light cone.Comment: 15 pages, LaTeX, 3 figures (7 PS files
Evolutionary phase space in driven elliptical billiards
We perform the first long-time exploration of the classical dynamics of a
driven billiard with a four dimensional phase space. With increasing velocity
of the ensemble we observe an evolution from a large chaotic sea with
stickiness due to regular islands to thin chaotic channels with diffusive
motion leading to Fermi acceleration. As a surprising consequence, we encounter
a crossover, which is not parameter induced but rather occurs dynamically, from
amplitude dependent tunable subdiffusion to universal normal diffusion in
momentum space. In the high velocity case we observe particle focusing in phase
space.Comment: 5 pages, 4 figure
Atom optical elements for Bose condensates
A simple model for atom optical elements for Bose condensate of trapped,
dilute alkali atomns is proposed and numerical simulations are presented to
illustrate its characteristics. We demonstrate ways of focusing and splitting
the condensate by modifying experimentally adjustable parameters. We show that
there are at least two ways of implementing atom optical elements: one may
modulate the interatomic scattering length in space, or alternatively, use a
sinusoidal, externally applied potential.Comment: 7 pages, 10 figure
The MGDO software library for data analysis in Ge neutrinoless double-beta decay experiments
The GERDA and Majorana experiments will search for neutrinoless double-beta
decay of germanium-76 using isotopically enriched high-purity germanium
detectors. Although the experiments differ in conceptual design, they share
many aspects in common, and in particular will employ similar data analysis
techniques. The collaborations are jointly developing a C++ software library,
MGDO, which contains a set of data objects and interfaces to encapsulate, store
and manage physical quantities of interest, such as waveforms and high-purity
germanium detector geometries. These data objects define a common format for
persistent data, whether it is generated by Monte Carlo simulations or an
experimental apparatus, to reduce code duplication and to ease the exchange of
information between detector systems. MGDO also includes general-purpose
analysis tools that can be used for the processing of measured or simulated
digital signals. The MGDO design is based on the Object-Oriented programming
paradigm and is very flexible, allowing for easy extension and customization of
the components. The tools provided by the MGDO libraries are used by both GERDA
and Majorana.Comment: 4 pages, 1 figure, proceedings for TAUP201
Non Degenerate Dual Atomic Parametric Amplifier: Entangled Atomic Fields
In this paper, we investigate the dynamics of two coupled quantum degenerate
atomic fields (BEC) interacting with two classical optical fields in the
nonlinear atom optics regime. Two photon interaction produces entangled
atom-atom pairs which exhibit nonclassical correlations. Since the system
involves the creation of two correlated atom pairs, we call it the
nondegenerate dual atomic parametric amplifier.Comment: 5 figure
Local Spectral Density for a Periodically Driven System of Coupled Quantum States with Strong Imperfection in Unperturbed Energies
A random matrix theory approach is applied in order to analyze the
localization properties of local spectral density for a generic system of
coupled quantum states with strong static imperfection in the unperturbed
energy levels. The system is excited by an external periodic field, the
temporal profile of which is close to monochromatic one. The shape of local
spectral density is shown to be well described by the contour obtained from a
relevant model of periodically driven two-states system with irreversible
losses to an external thermal bath. The shape width and the inverse
participation ratio are determined as functions both of the Rabi frequency and
of parameters specifying the localization effect for our system in the absence
of external field.Comment: 6 pages, 5 figures, submitted to Optics and Spectroscop
Quantum optics of a Bose-Einstein condensate coupled to a quantized light field
We consider the interaction between a Bose-Einstein condensate and a
single-mode quantized light field in the presence of a strong far off-resonant
pump laser. The dynamics is characterized by an exponential instability, hence
the system acts as an atom-photon parametric amplifier. Triggered by a small
injected probe field, or simply by quantum noise, entangled atom-photon pairs
are created which exhibit non-classical correlations similar to those seen
between photons in the optical parametric amplifier. In addition, the quantum
statistics of the matter and light fields depend strongly on the initial state
which triggers the amplifier. Thus by preparing different initial states of the
light field, one can generate matter waves in a variety of quantum states,
demonstrating optical control over the quantum statistics of matter waves
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