36,578 research outputs found
Can Modus Vivendi Save Liberalism from Moralism? A Critical Assessment of John Gray’s Political Realism
This chapter assesses John Gray’s modus vivendi-based justification for liberalism. I argue that his approach is preferable to the more orthodox deontological or teleological justificatory strategies, at least because of the way it can deal with the problem of diversity. But then I show how that is not good news for liberalism, for grounding liberal political authority in a modus vivendi undermines liberalism’s aspiration to occupy a privileged normative position vis-à-vis other kinds of regimes. So modus vivendi can save liberalism from moralism, but at cost many liberals will not be prepared to pay
Quantum Properties of a Which-Way Detector
We explore quantum properties of a which-way detector using three versions of
an idealized two slit arrangements. Firstly we derive complementarity relations
for the detector; secondly we show how the "experiment" may be altered in such
a way that using single position measurement on the screen we can obtain
quantum erasure. Finally we show how to construct a superposition of "wave" and
"particle" components
Quantum erasure in the presence of a thermal bath: the effects of system-environment microscopic correlations
We investigate the role of the environment in a quantum erasure setup in the
cavity quantum electrodynamics domain. Two slightly different schemes are
analyzed. We show that the effects of the environment vary when a scheme is
exchanged for another. This can be used to estimate the macroscopic parameters
related to the system-environment microscopic correlations.Comment: 10 pages, 2 figure
Coherent phenomena in semiconductors
A review of coherent phenomena in photoexcited semiconductors is presented.
In particular, two classes of phenomena are considered: On the one hand the
role played by optically-induced phase coherence in the ultrafast spectroscopy
of semiconductors; On the other hand the Coulomb-induced effects on the
coherent optical response of low-dimensional structures.
All the phenomena discussed in the paper are analyzed in terms of a
theoretical framework based on the density-matrix formalism. Due to its
generality, this quantum-kinetic approach allows a realistic description of
coherent as well as incoherent, i.e. phase-breaking, processes, thus providing
quantitative information on the coupled ---coherent vs. incoherent--- carrier
dynamics in photoexcited semiconductors.
The primary goal of the paper is to discuss the concept of quantum-mechanical
phase coherence as well as its relevance and implications on semiconductor
physics and technology. In particular, we will discuss the dominant role played
by optically induced phase coherence on the process of carrier photogeneration
and relaxation in bulk systems. We will then review typical field-induced
coherent phenomena in semiconductor superlattices such as Bloch oscillations
and Wannier-Stark localization. Finally, we will discuss the dominant role
played by Coulomb correlation on the linear and non-linear optical spectra of
realistic quantum-wire structures.Comment: Topical review in Semiconductor Science and Technology (in press)
(Some of the figures are not available in electronic form
Protecting, Enhancing and Reviving Entanglement
We propose a strategies not only to protect but also to enhance and revive
the entanglement in a double Jaynes-Cummings model. We show that such
surprising features arises when Zeno-like measurements are performed during the
dynamical process
Strong coupling expansion of chiral models
A general precedure is outlined for an algorithmic implementation of the
strong coupling expansion of lattice chiral models on arbitrary lattices. A
symbolic character expansion in terms of connected values of group integrals on
skeleton diagrams may be obtained by a fully computerized approach.Comment: 2 pages, PostScript file, contribution to conference LATTICE '9
Electric field sensing with a scanning fiber-coupled quantum dot
We demonstrate the application of a fiber-coupled quantum-dot-in-a-tip as a
probe for scanning electric field microscopy. We map the out-of-plane component
of the electric field induced by a pair of electrodes by measurement of the
quantum-confined Stark effect induced on a quantum dot spectral line. Our
results are in agreement with finite element simulations of the experiment.
Furthermore, we present results from analytic calculations and simulations
which are relevant to any electric field sensor embedded in a dielectric tip.
In particular, we highlight the impact of the tip geometry on both the
resolution and sensitivity.Comment: 10 pages, 4 figure
Educational studies of cosmic rays with telescope of Geiger-Muller counters
A group of high school students (XII Liceum) in the framework of the Roland
Maze Project has built a compact telescope of three Geiger-Muller counters. The
connection between the telescope and PC computer was also created and programed
by students involved in the Project. This has allowed students to use their
equipment to perform serious scientific measurements concerning the single
cosmic ray muon flux at ground level and below. These measurements were then
analyzed with the programs based on the 'nowadays' knowledge on statistics. An
overview of the apparatus, methods and results were presented at several
students conferences and recently won the first prize in a national competition
of high school students scientific work. The telescope itself, in spite of its
'scientific' purposes, is built in such a way that it is hung on a wall in a
school physics lab and counts muons continuously. This can help to raise the
interest for studying physics among others. At present a few (3) groups of
young participants of the Roland Maze Project have already built their own
telescopes for their schools and some others are working on it. This work is a
perfect example of what can be done by young people when respective
opportunities are created by more experienced researchers and a little help and
advice is given.Comment: 5 figures, 10 page
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