9,464 research outputs found
A template-based approach for the generation of abstractable and reducible models of featured networks
We investigate the relationship between symmetry reduction and inductive reasoning when applied to model checking networks of featured components. Popular reduction techniques for combatting state space explosion in model checking, like abstraction and symmetry reduction, can only be applied effectively when the natural symmetry of a system is not destroyed during specification. We introduce a property which ensures this is preserved, open symmetry. We describe a template-based approach for the construction of open symmetric Promela specifications of featured systems. For certain systems (safely featured parameterised systems) our generated specifications are suitable for conversion to abstract specifications representing any size of network. This enables feature interaction analysis to be carried out, via model checking and induction, for systems of any number of featured components. In addition, we show how, for any balanced network of components, by using a graphical representation of the features and the process communication structure, a group of permutations of the underlying state space of the generated specification can be determined easily. Due to the open symmetry of our Promela specifications, this group of permutations can be used directly for symmetry reduced model checking.
The main contributions of this paper are an automatic method for developing open symmetric specifications which can be used for generic feature interaction analysis, and the novel application of symmetry detection and reduction in the context of model checking featured networks.
We apply our techniques to a well known example of a featured network – an email system
The Tcc = DD* molecular state
We show that the molecule-like configuration of DD^* enables weak binding
with two realistic potential models (Bhaduri and Grenoble AL1). Three-body
forces may increase the binding and strengthen the cc diquark configuration. As
a signature we propose the branching ratio between radiative and pionic decay.Comment: 19 pages, 18 figures, revised version, to be published in Few-Body
System
Generation of entangled states and error protection from adiabatic avoided level crossings
We consider the environment-affected dynamics of self-interacting
particles living in one-dimensional double wells. Two topics are dealt with.
First, we consider the production of entangled states of two-level systems. We
show that by adiabatically varying the well biases we may dynamically generate
maximally entangled states, starting from initially unentangled product states.
Entanglement degradation due to a common type of environmental influence is
then computed by solving a master equation. However, we also demonstrate that
entanglement production is unaffected if the system-environment coupling is of
the type that induces ``motional narrowing''. As our second but related topic,
we construct a different master equation that seamlessly merges error
protection/detection dynamics for quantum information with the environmental
couplings responsible for producing the errors in the first place. Adiabatic
avoided crossing schemes are used in both topics.Comment: 14 pages, 6 figures. Minor changes. To appear in Phys. Rev.
Laser spectroscopic studies of the pure rotational U_0(0) and W_0(0) transitions of solid parahydrogen
High resolution spectrum of multipole-induced transitions of solid parahydrogen was recorded using diode and difference frequency laser spectroscopy. The J=4<--0 pure rotational U_0(0) transition observed in the diode spectrum agrees well in frequency with the value reported by Balasubramanian et al. [Phys. Rev. Lett. 47, 1277 (1981)] but we observed a spectral width smaller by about a factor of 4. The J=6<--0 W_0(0) transition was observed to be exceedingly sharp, with a width of ~70 MHz, using a difference frequency spectrometer with tone-burst modulation. This transition is composed of three components with varying relative intensity depending upon the direction of polarization of laser radiation. These components were interpreted as the splitting of the M levels in the J=6 state due to crystal field interactions. In addition, a new broad feature was found at 2452.4 cm^(−1) in the low resolution Fourier-transform infrared (FTIR) spectrum of solid hydrogen and was assigned to be the phonon branch W_R(0) transition of the W_0(0) line. The selection rules, crystal field splitting of J=4 and J=6 rotons, and the measured linewidth based on these observations are discussed
Spectral structure and decompositions of optical states, and their applications
We discuss the spectral structure and decomposition of multi-photon states.
Ordinarily `multi-photon states' and `Fock states' are regarded as synonymous.
However, when the spectral degrees of freedom are included this is not the
case, and the class of `multi-photon' states is much broader than the class of
`Fock' states. We discuss the criteria for a state to be considered a Fock
state. We then address the decomposition of general multi-photon states into
bases of orthogonal eigenmodes, building on existing multi-mode theory, and
introduce an occupation number representation that provides an elegant
description of such states that in many situations simplifies calculations.
Finally we apply this technique to several example situations, which are highly
relevant for state of the art experiments. These include Hong-Ou-Mandel
interference, spectral filtering, finite bandwidth photo-detection, homodyne
detection and the conditional preparation of Schr\"odinger Kitten and Fock
states. Our techniques allow for very simple descriptions of each of these
examples.Comment: 12 page
Out-of-equilibrium collective oscillation as phonon condensation in a model protein
In the first part of the present paper (theoretical), the activation of
out-of-equilibrium collective oscillations of a macromolecule is described as a
classical phonon condensation phenomenon. If a macromolecule is modeled as an
open system, that is, it is subjected to an external energy supply and is in
contact with a thermal bath to dissipate the excess energy, the internal
nonlinear couplings among the normal modes make the system undergo a
non-equilibrium phase transition when the energy input rate exceeds a threshold
value. This transition takes place between a state where the energy is
incoherently distributed among the normal modes, to a state where the input
energy is channeled into the lowest frequency mode entailing a coherent
oscillation of the entire molecule. The model put forward in the present work
is derived as the classical counterpart of a quantum model proposed long time
ago by H. Fr\"ohlich in the attempt to explain the huge speed of enzymatic
reactions. In the second part of the present paper (experimental), we show that
such a phenomenon is actually possible. Two different and complementary THz
near-field spectroscopic techniques, a plasmonic rectenna, and a micro-wire
near-field probe, have been used in two different labs to get rid of artefacts.
By considering a aqueous solution of a model protein, the BSA (Bovine Serum
Albumin), we found that this protein displays a remarkable absorption feature
around 0.314 THz, when driven in a stationary out-of-thermal equilibrium state
by means of optical pumping. The experimental outcomes are in very good
qualitative agreement with the theory developed in the first part, and in
excellent quantitative agreement with a theoretical result allowing to identify
the observed spectral feature with a collective oscillation of the entire
molecule.Comment: 49 pages, 10 figures; Physical Review X, (2018) in pres
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