99 research outputs found
Towards a first observation of magneto-electric directional anisotropy and linear birefringence in gases
In this contribution to PSAS'2010 we report on recent progress on an
experiment aimed at measuring small optical directional anisotropies by
frequency metrology in a high finesse ring cavity. We focus on our first
experimental goal, the measurement of magneto-electric effects in gases. After
a review of the expected effects in our set-up, we present the apparatus and
the measurement procedure, showing that we already have the necessary
sensitivity to start novel experiments.Comment: Proceedings of PSAS'2010, to be published in Canadian Journal of
Physics, 2011 Ja
Directed transport born from chaos in asymmetric antidot structures
It is shown that a polarized microwave radiation creates directed transport
in an asymmetric antidot superlattice in a two dimensional electron gas. A
numerical method is developed that allows to establish the dependence of this
ratchet effect on several parameters relevant for real experimental studies. It
is applied to the concrete case of a semidisk Galton board where the electron
dynamics is chaotic in the absence of microwave driving. The obtained results
show that high currents can be reached at a relatively low microwave power.
This effect opens new possibilities for microwave control of transport in
asymmetric superlattices.Comment: 8 pages, 10 figure
Demonstration of the spatial separation of the entangled quantum side-bands of an optical field
Quantum optics experiments on "bright" beams typically probe correlations
between side-band modes. However the extra degree of freedom represented by
this dual mode picture is generally ignored. We demonstrate the experimental
operation of a device which can be used to separate the quantum side-bands of
an optical field. We use this device to explicitly demonstrate the quantum
entanglement between the side-bands of a squeezed beam
Photogalvanic current in artificial asymmetric nanostructures
We develop a theoretic description of the photogalvanic current induced by a
high frequency radiation in asymmetric nanostructures and show that it
describes well the results of numerical simulations. Our studies allow to
understand the origin of the electronic ratchet transport in such systems and
show that they can be used for creation of new types of detectors operating at
room temperature in a terahertz radiation range.Comment: 11 pages, 9 figs, EPJ latex styl
Micro-econometric and Micro-Macro Linked Models: Sequential Macro-Micro Modelling with Behavioral Microsimulations
Analyzing the poverty and distributional impact of macro events requires understanding how shocks or policy changes on the macro level affect household income and consumption. It is clear that this poses a formidable task, which of course raises the question of the appropriate methodology to address such questions. This paper presents one possible approach: A sequential methodology that combines a macroeconomic model with a behavioral micro-simulation. We discuss the merits and shortcomings of this approach with a focus on developing country applications with a short to medium run time horizon. - This chapter is a re-print of: Lay, J. (2010). Sequential macro-micro modelling with behavioural microsimulations. International Journal of Microsimulation, 3(1), 24-34
Efficiency optimization in a correlation ratchet with asymmetric unbiased fluctuations
The efficiency of a Brownian particle moving in periodic potential in the
presence of asymmetric unbiased fluctuations is investigated. We found that
there is a regime where the efficiency can be a peaked function of temperature,
which proves that thermal fluctuations facilitate the efficiency of energy
transformation, contradicting the earlier findings (H. kamegawa et al. Phys.
Rev. Lett. 80 (1998) 5251). It is also found that the mutual interplay between
asymmetry of fluctuation and asymmetry of the potential may induce optimized
efficiency at finite temperature. The ratchet is not most efficiency when it
gives maximum current.Comment: 10 pages, 7 figure
Axion-like-particle search with high-intensity lasers
We study ALP-photon-conversion within strong inhomogeneous electromagnetic
fields as provided by contemporary high-intensity laser systems. We observe
that probe photons traversing the focal spot of a superposition of Gaussian
beams of a single high-intensity laser at fundamental and frequency-doubled
mode can experience a frequency shift due to their intermittent propagation as
axion-like-particles. This process is strongly peaked for resonant masses on
the order of the involved laser frequencies. Purely laser-based experiments in
optical setups are sensitive to ALPs in the mass range and can
thus complement ALP searches at dipole magnets.Comment: 25 pages, 2 figure
Birefringence of interferential mirrors at normal incidence Experimental and computational study
In this paper we present a review of the existing data on interferential
mirror birefringence. We also report new measurements of two sets of mirrors
that confirm that mirror phase retardation per reflection decreases when mirror
reflectivity increases. We finally developed a computational code to calculate
the expected phase retardation per reflection as a function of the total number
of layers constituting the mirror. Different cases have been studied and we
have compared computational results with the trend of the experimental data.
Our study indicates that the origin of the mirror intrinsic birefringence can
be ascribed to the reflecting layers close to the substrate.Comment: To be published in Applied Physics
Rectification and Phase Locking for Particles on Two Dimensional Periodic Substrates
We show that a novel rectification phenomena is possible for overdamped
particles interacting with a 2D periodic substrate and driven with a
longitudinal DC drive and a circular AC drive. As a function of DC amplitude,
the longitudinal velocity increases in a series of quantized steps with
transverse rectification occuring near these transitions. We present a simple
model that captures the quantization and rectification behaviors.Comment: 4 pages, 4 postscript figure
Atomic diffraction from nanostructured optical potentials
We develop a versatile theoretical approach to the study of cold-atom
diffractive scattering from light-field gratings by combining calculations of
the optical near-field, generated by evanescent waves close to the surface of
periodic nanostructured arrays, together with advanced atom wavepacket
propagation on this optical potential.Comment: 8 figures, 10 pages, submitted to Phys. Rev.
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