Bohmian Trajectories of Airy Packets

The discovery of Berry and Balazs in 1979 that the free-particle Schr\"odinger equation allows a non-dispersive and accelerating Airy-packet solution has taken the folklore of quantum mechanics by surprise. Over the years, this intriguing class of wave packets has sparked enormous theoretical and experimental activities in related areas of optics and atom physics. Within the Bohmian mechanics framework, we present new features of Airy wave packet solutions to Schr\"odinger equation with time-dependent quadratic potentials. In particular, we provide some insights to the problem by calculating the corresponding Bohmian trajectories. It is shown that by using general space-time transformations, these trajectories can display a unique variety of cases depending upon the initial position of the individual particle in the Airy wave packet. Further, we report here a myriad of nontrivial Bohmian trajectories associated to the Airy wave packet. These new features are worth introducing to the subject's theoretical folklore in light of the fact that the evolution of a quantum mechanical Airy wave packet governed by the Schr\"odinger equation is analogous to the propagation of a finite energy Airy beam satisfying the paraxial equation. Numerous experimental configurations of optics and atom physics have shown that the dynamics of Airy beams depends significantly on initial parameters and configurations of the experimental set-up.Comment: 8 page

Dividing Line between Quantum and Classical Trajectories: Bohmian Time Constant

This work proposes an answer to a challenge posed by Bell on the lack of clarity in regards to the line between the quantum and classical regimes in a measurement problem. To this end, a generalized logarithmic nonlinear Schr\"odinger equation is proposed to describe the time evolution of a quantum dissipative system under continuous measurement. Within the Bohmian mechanics framework, a solution to this equation reveals a novel result: it displays a time constant which should represent the dividing line between the quantum and classical trajectories. It is shown that continuous measurements and damping not only disturb the particle but compel the system to converge in time to a Newtonian regime. While the width of the wave packet may reach a stationary regime, its quantum trajectories converge exponentially in time to classical trajectories. In particular, it is shown that damping tends to suppress further quantum effects on a time scale shorter than the relaxation time of the system. If the initial wave packet width is taken to be equal to 2.8 10^{-15} m (the approximate size of an electron), the Bohmian time constant is found to have an upper limit, i. e., ${\tau_{B\max}} = {10^{- 26}}s$

Use of the terms "Wellbeing" and "Quality of Life" in health sciences: A conceptual framework

Background and Objectives: The assessment of wellbeing is a top priority in health sciences. The aim of this paper is to review the history of the concept of wellbeing and “Quality of Life” (QoL), and to understand the theories and assumptions that guided this field in order to provide a conceptual framework that may eventually facilitate the development of a formal synset (grouping of synonyms and semantically similar terms) of health-related wellbeing Methods: The history of the concept of wellbeing and QoL was reviewed in order to provide a conceptual framework. Results: Huge differences exist on the definition of “Wellbeing” and its relationship with QoL, “Happiness” and “Functioning” in the health context. From a dimensional perspective, health related wellbeing could be regarded as an overarching construct characterised by asymmetrical polarity, where “wellbeing” embeds the concept of “ill-being” as “health” incorporates de concept of “disease”. Conclusions: A common conceptual framework of these terms may eventually facilitate the development of a formal synset of health-related wellbeing. This terminological clarification should be part of a new taxonomy of health-related wellbeing based on the International Classification of Functioning, Disability and Health (ICF) framework that may facilitate knowledge transfer across different sectors and semantic interoperability for care management and planningThe research leading to these results has received funding from the European Community’s Seventh Framework Programme under grant agreement numbers 223071 (COURAGE in Europe) and 282586 (ROAMER), from the Instituto de Salud Carlos III-FIS research grant number PS09/00295, and from the Spanish Ministry of Science and Innovation ACI-Promociona (ACI2009-1010 and ACI- 2011-1080). The study was supported by the Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos II

Communication: Semiclassical perturbation theory for the quantum diffractive scattering of atoms on thermal surfaces

Inspired by the semiclassical perturbation theory of Hubbard and Miller [J. Chem. Phys. 80, 5827 (1984)10.1063/1.446609], we derive explicit expressions for the angular distribution of particles scattered from thermal surfaces. At very low surface temperature, the observed experimental background scattering is proportional to the spectral density of the phonons. The angular distribution is a sum of diffraction peaks and a broad background reflecting the spectral density. The theory is applied to measured angular distributions of Ne, Ar, and Kr scattered from a Cu(111) surface. © 2012 American Institute of Physics.This work has been graciously supported by grants from the Israel Science Foundation and the German-Israel Foundation for Basic Research, FIS2011-29596-C01-02 (Spain) and COST action MP1006.Peer Reviewe

A new approach to atom scattering from conducting surfaces: The effective electron-phonon Debye-Waller factor

Photodynamics conference; Mendoza, Argentina. 9th-13st of May 2016 ; http://photodynamics9.wixsite.com/phd9Peer Reviewe