1,721,194 research outputs found
Quantum forced oscillator via Wigner transform
No full textIn this paper we review the basic results concerning the Wigner transform and critically discuss the problem of the reversibility. Then we completely solve the harmonic/inverted forced quantum oscillator in such a framework; eventually, the tunnel effect for the forced inverted oscillator is discussed
Resonances crossing and electric field quantum sensors
Full text linkWe propose a theoretical model for a quantum sensor that can determine in a very simple way whether the intensity of an electric field has an assigned value or not. It is based on the fact that when an exact crossing of the imaginary parts of the resonances occurs in a double-well quantum system subject to an external DC electric field, a damped beating phenomenon occurs, which is absent if there is no such a crossing. This result is then tested numerically on an explicit one-dimensional model
Stationary solutions to cubic nonlinear Schrödinger equations with quasi-periodic boundary conditions
No full textIn this paper we give the quantization rules to determine the normalized stationary solutions to the cubic nonlinear Schrödinger equation with quasi-periodic conditions on a given interval. Similarly to what happen in the Floquet's theory for linear periodic operators, also in this case some kind of band functions there exist
Quantum resonances crossing and survival amplitude for double-well potentials
No full textIn the case of crossings of isolated pairs of quantum resonances for double-well potentials it is possible to observe that, under appropriate conditions, the associated metastable states are equally localized on both wells. This property, together with the fact that the imaginary parts of the two resonances coincide, results in the establishment of an interference phenomenon between the two metastable states that characterizes the time dynamics of certain physical observables. In this way, it is possible to lay the theoretical foundations for the design of a quantum device to assess whether or not the model's parameters assume pre-assigned values
On a mathematical model for a damped and driven double-well Bose–Einstein condensate
No full textIn this paper we consider a two-mode dynamical system as a model for a driven one-dimensional damped Bose–Einstein condensate in a double-well trapping potential. In the case of a constant external driving force the existence and stability of stationary solutions are discussed in relation to the values of the physical parameters. In the case of a time-dependent periodic external driving force the existence of limit cycles is proved, and the amplitude of these limit cycles exhibits a jump phenomenon for critical values of the physical parameters
Synthesis of Natural Compounds Based on the [3,7]-Diazabicyclo[3.3.1]nonane (Bispidine) Core
No full textThe [3,7]-diazabicyclo[3.3.1]nonane (bispidine) structure is found in several interesting naturally occurring alkaloids. The most representative components are the tetracyclic alkaloid (−)-sparteine and the tricyclic (−)-cytisine alkaloids. Their biological activities have been known for a long time. In the literature, different syntheses of both tetracyclic and tricyclic structures have been reported, especially in the last few years, when a number of new reports renewed the interest in these fascinating molecules. Bicyclic bispidine derivatives have been thoroughly investigated in recent times also for their applications as catalysts, metal chelating agents, and lately in coordination polymers chemistry. In this review, we describe the most relevant strategies for the synthesis of molecules based on the [3,7]-diazabicyclo[3.3.1]nonane core, related to (−)-sparteine and (−)-cytisine alkaloids
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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