Why does such a successful theory like Quantum Mechanics have so many mysteries? The history of this theory is replete with dubious interpretations and controversies, and yet a knowledge of its predictions, however, contributed to the amazing technological revolution of the last hundred years. In its very beginning Einstein pointed out that there was something missing, due to contradictions with the relativity theory. So, even though Quantum Mechanics explains all the nanoscale physical phenomena, there were many attempts to find a way to “complete” it, e.g. hidden-variable theories. In this paper, we discuss some of those enigmas, with special attention to the concepts of physical reality imposed by quantum mechanics, the role of the observer, prediction limits, a definition of collapse, and how to deal with correlated states (the basic strategy for quantum computers and quantum teleportation). That discussion is carried out within the framework of accepting that there is in fact nothing important missing, rather we are just restricted by the limitations imposed by quantum mechanics. The mysteries are thus explained by a proper interpretation of those limitations, which is achieved by introducing two interpretation rules within the Copenhagen paradigm.

Pode-se escolher um tópico complexo em mecânica quântica e discuti-lo com um número mínimo de equações, e de forma simplificada para que um público com apenas conhecimento básico em física possa entender? Essa foi a pergunta apresentada aos alunos de pós-graduação das disciplinas de um ano de Mecânica Quântica I e II da Universidade Estadual de Campinas (UNICAMP), baseadas no livro “Quantum Mechanics” de J. J. Sakurai e Jim Napolitano. Os primeiros sete autores desse artigo são os alunos de pós-graduação (em ordem alfabética) que aceitaram o desafio. O tópico escolhido foi estados quânticos delocalizados, e será discutido utilizando termos coloquiais como fantasmas quânticos, ações fantasmagóricas, entidades divididas e capa de invisibilidade.

Can you pick a complex subject in quantum mechanics and discuss it with a minimum number of equations, in a simplified form that the general scientific public could understand? This was a question presented to graduate students of the one-year Quantum Mechanics course based on the text book Modern Quantum Mechanics by J. J. Sakurai and Jim Napolitano, at the State University of Campinas (UNICAMP), Brazil. The first seven authors of this paper are graduate students (alphabetical order) that accepted to try it. The chosen subject was “delocalized quantum states”, and it will be discussed using colloquial terms like quantum ghosts, spooky action, splitting beings and invisibility cloak.

This paper is a data basis which includes tables of integral, differential, and momentum transfer cross sections for elastic electron scattering from CF4, CCl4, SiCl4, SiBr4, SiI4, CH3F CH2F2, CHF3, CH3Cl, CH2Cl2, CHCl3, CF3Cl, CF2Cl2, CFCl3, CH3Br, CH3I, SiH3Cl, SiH3Br, SiH3I, GeH3Cl, GeH3Br, SnH3Br, C2H6, Si2H6, Ge2H6, B2H6, Ga2H6, H2O, H2S, H2Se, H2Te, trimethylarsine (TMAs), N2O, and O3. These tables show our new results, along with some of our previously published cross sections, and can easily be compared to future experimental data and other new theoretical results. Our scattering amplitudes were calculated using the Schwinger multichannel method with norm-conserving pseudopotentials. Our results are in good agreement with other theoretical data and experimental results when available.

This paper reports results for rotational excitation of H2O and H2S molecules by electron impact. It is also a databasis including tables of previously published rotationally resolved cross sections for CH4, SiH4, GeH4, SnH4, PbH4, NH3, PH3, AsH3, SbH3, CF4, CCl4, SiCl4 SiBr4, and SiI4. Our scattering amplitudes were calculated using the Schwinger multichannel method with norm-conserving pseudopotentials and the rotational resolved cross sections were obtained with the help of the adiabatic nuclei rotation approximation. Our results are in good agreement with other theoretical data and experimental results when available.

We report elastic differential cross sections (DCS) for the scattering of electron by H2, CH4, C2H4, SiH4, and H2O in the 5 to 20 eV energy range. These cross sections were obtained using the Schwinger variational principle. In our procedures the scattering wave function is expanded as a combination of plane waves. In the present implementation the exchange potential and polarization effects are not considered and all results are obtained at the static level of approximation. For all molecules, except H2, our calculated DCS agree reasonably well with avaliable experimental data and with other theoretical results (obtained at the static-exchange level of approximation). Our study suggests that the Schwinger variational principle with plane wave expansion may become an efficient method for studying electron-molecule scattering.