407 research outputs found
New remarks on the linear constraint self-dual boson and Wess-Zumino terms
In this work we prove in a precise way that the soldering formalism can be
applied to the Srivastava chiral boson (SCB), in contradiction with some
results appearing in the literature. We have promoted a canonical
transformation that shows directly that the SCB is composed of two
Floreanini-Jackiw's particles with the same chirality which spectrum is a
vacuum-like one. As another conflictive result we have proved that a
Wess-Zumino term used in the literature consists of the scalar field, once
again denying the assertion that the WZ term adds a new degree of freedom to
the SCB theory in order to modify the physics of the system.Comment: 6 pages, Revtex. Final version to appear in Physical Review
Conditional large Fock state preparation and field state reconstruction in Cavity QED
We propose a scheme for producing large Fock states in Cavity QED via the
implementation of a highly selective atom-field interaction. It is based on
Raman excitation of a three-level atom by a classical field and a quantized
field mode. Selectivity appears when one tunes to resonance a specific
transition inside a chosen atom-field subspace, while other transitions remain
dispersive, as a consequence of the field dependent electronic energy shifts.
We show that this scheme can be also employed for reconstructing, in a new and
efficient way, the Wigner function of the cavity field state.Comment: 4 Revtex pages with 3 postscript figures. Submitted for publicatio
Dicke-Type Energy Level Crossings in Cavity-Induced Atom Cooling: Another Superradiant Cooling
This paper is devoted to energy-spectral analysis for the system of a
two-level atom coupled with photons in a cavity. It is shown that the
Dicke-type energy level crossings take place when the atom-cavity interaction
of the system undergoes changes between the weak coupling regime and the strong
one. Using the phenomenon of the crossings we develop the idea of
cavity-induced atom cooling proposed by the group of Ritsch, and we lay
mathematical foundations of a possible mechanism for another superradiant
cooling in addition to that proposed by Domokos and Ritsch. The process of our
superradiant cooling can function well by cavity decay and by control of the
position of the atom, at least in (mathematical) theory, even if there is
neither atomic absorption nor atomic emission of photons.Comment: 15 pages; 8 figure
Protocolos de Micropropagação de Plantas. I-Batata.
bitstream/item/44084/1/documento-317.pd
Micropropagação de batata 'BRS Ana': produção de material básico com alta sanidade.
bitstream/item/60642/1/CIRCULAR-118.pd
A general scheme for the effective-mass Schrodinger equation and the generation of the associated potentials
A systematic procedure to study one-dimensional Schr\"odinger equation with a
position-dependent effective mass (PDEM) in the kinetic energy operator is
explored. The conventional free-particle problem reveals a new and interesting
situation in that, in the presence of a mass background, formation of bound
states is signalled. We also discuss coordinate-transformed, constant-mass
Schr\"odinger equation, its matching with the PDEM form and the consequent
decoupling of the ambiguity parameters. This provides a unified approach to
many exact results known in the literature, as well as to a lot of new ones.Comment: 16 pages + 1 figure; minor changes + new "free-particle" problem;
version published in Mod. Phys. Lett.
PT-symmetric Solutions of Schrodinger Equation with position-dependent mass via Point Canonical Transformation
PT-symmetric solutions of Schrodinger equation are obtained for the Scarf and
generalized harmonic oscillator potentials with the position-dependent mass. A
general point canonical transformation is applied by using a free parameter.
Three different forms of mass distributions are used. A set of the energy
eigenvalues of the bound states and corresponding wave functions for target
potentials are obtained as a function of the free parameter.Comment: 13 page
Qualitative aspects of entanglement in the Jaynes-Cummings model with an external quantum field
We present a mathematical procedure which leads us to obtain analytical
solutions for the atomic inversion and Wigner function in the framework of the
Jaynes-Cummings model with an external quantum field, for any kinds of cavity
and driving fields. Such solutions are expressed in the integral form, with
their integrands having a commom term that describes the product of the
Glauber-Sudarshan quasiprobability distribution functions for each field, and a
kernel responsible for the entanglement. Considering two specific initial
states of the tripartite system, the formalism is then applied to calculate the
atomic inversion and Wigner function where, in particular, we show how the
detuning and amplitude of the driving field modify the entanglement. In
addition, we also obtain the correctComment: 15 pages and 21 figure
A generalized quantum nonlinear oscillator
We examine various generalizations, e.g. exactly solvable, quasi-exactly
solvable and non-Hermitian variants, of a quantum nonlinear oscillator. For all
these cases, the same mass function has been used and it has also been shown
that the new exactly solvable potentials possess shape invariance symmetry. The
solutions are obtained in terms of classical orthogonal polynomials
A RAVE investigation on Galactic open clusters I. Radial velocities and metallicities
Context. Galactic open clusters (OCs) mainly belong to the young stellar population in the Milky Way disk, but are there groups and complexes of OCs that possibly define an additional level in hierarchical star formation? Current compilations are too incomplete to address this question, especially regarding radial velocities (RVs) and metallicities ([M/H]).
Aims. Here we provide and discuss newly obtained RV and [M/H] data, which will enable us to reinvestigate potential groupings of open clusters and associations.
Methods. We extracted additional RVs and [M/H] from the RAdial Velocity Experiment (RAVE) via a cross-match with the Catalogue of Stars in Open Cluster Areas (CSOCA). For the identified OCs in RAVE we derived (RV) over bar and ([M/H]) over bar from a cleaned working sample and compared the results with previous findings.
Results. Although our RAVE sample does not show the same accuracy as the entire survey, we were able to derive reliable (RV) over bar for 110 Galactic open clusters. For 37 OCs we publish (RV) over bar for the first time. Moreover, we determined ([M/H]) over bar for 81 open clusters, extending the number of OCs with ([M/H]) over bar by 69
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