14 research outputs found
On the Quantum Phase Operator for Coherent States
In papers by Lynch [Phys. Rev. A41, 2841 (1990)] and Gerry and Urbanski
[Phys. Rev. A42, 662 (1990)] it has been argued that the phase-fluctuation
laser experiments of Gerhardt, B\"uchler and Lifkin [Phys. Lett. 49A, 119
(1974)] are in good agreement with the variance of the Pegg-Barnett phase
operator for a coherent state, even for a small number of photons. We argue
that this is not conclusive. In fact, we show that the variance of the phase in
fact depends on the relative phase between the phase of the coherent state and
the off-set phase of the Pegg-Barnett phase operator. This off-set
phase is replaced with the phase of a reference beam in an actual experiment
and we show that several choices of such a relative phase can be fitted to the
experimental data. We also discuss the Noh, Foug\`{e}res and Mandel [Phys.Rev.
A46, 2840 (1992)] relative phase experiment in terms of the Pegg-Barnett phase
taking post-selection conditions into account.Comment: 8 pages, 8 figures. Typographical errors and misprints have been
corrected. The outline of the paper has also been changed. Physica Scripta
(in press
Pension reform in Nigeria : how not to `learn from others'
While the Chilean pension reform has received considerable attention, its emulation in Nigeria has not. This article is the first in-depth analysis of the Nigerian reform. It suggests that the Nigerian authorities failed to learn the lessons of Chile. They transposed a system that both failed to serve the country from which it was copied and that is inappropriate to the country to which it was copied. For countries such as Nigeria, alternative forms of provision for old age are needed. A social pension might be considered