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Analysis of the Jun Ishiwara's "The universal meaning of the quantum of action"
Here we present an analysis of the paper "Universelle Bedeutung des
Wirkungsquantums" (The universal meaning of the quantum of action), published
by Jun Ishiwara in German in the "Proceedings of Tokyo Mathematico-Physical
Society 8 (1915) 106-116". In his work, Ishiwara, established in the Sendai
University, Japan, proposed - simultaneously with Arnold Sommerfeld, William
Wilson and Niels Bohr in Europe - the phase-space-integral quantization, a rule
that would be incorporated into the old-quantum-theory formalism. The
discussions and analysis render this paper fully accessible to undergraduate
students of physics with elementary knowledge of quantum mechanics.Comment: 12 page
Understanding the Pointer States
In quantum mechanics, pointer states are eigenstates of the observable of the
measurement apparatus that represent the possible positions of the display
pointer of the equipment. The origin of this concept lies in attempts to fill
the blanks in the Everett's relative-state interpretation, and to make it a
fully valid description of physical reality. To achieve this, it was necessary
to consider not only the main system interacting with the measurement apparatus
(like von Neumann and Everett did) but also the role of the environment in
eliminating correlations between different possible measurements when
interacting with the measurement apparatus. The interaction of the environment
with the main system (and the measurement apparatus) is the core of the
decoherence theory, which followed Everett's thesis. In this article, we review
the measurement process according to von Neumann, Everett's relative state
interpretation, the purpose of decoherence and some of its follow-up until
Wojciech Zurek's primordial paper that consolidated the concept of pointer
state, previously presented by Heinz Dieter Zeh. Employing a simple physical
model consisting of a pair of two-level systems -- one representing the main
system, the other the measurement apparatus -- and a thermal bath --
representing the environment -- we show how pointer states emerge, explaining
its contributions to the question of measurement in quantum mechanics, as well
as its limitations. Finally, we briefly show some of its consequences. This
paper is accessible to readers with elementary knowledge about quantum
mechanics, on the level of graduate courses.Comment: 29 pages (20 for main text and references, 9 for appendices
Decreto nº 7.385, de 8 de dezembro de 2010 [institui o Sistema UNA-SUS]
Decreto que institui o Sistema Universidade Aberta do Sistema Único
de Saúde - UNA-SUS, e dá outras providências
- …