2,816 research outputs found
Changes in union membership over time : a panel analysis for West Germany
Despite the apparent stability of the wage bargaining institutions in West Germany, aggregate union membership has been declining dramatically since the early 90's. However, aggregate gross membership numbers do not distinguish by employment status and it is impossible to disaggregate these sufficiently. This paper uses four waves of the German Socioeconomic Panel in 1985, 1989, 1993, and 1998 to perform a panel analysis of net union membership among employees. We estimate a correlated random effects probit model suggested in Chamberlain (1984) to take proper account of individual specfic effects. Our results suggest that at the individual level the propensity to be a union member has not changed considerably over time. Thus, the aggregate decline in membership is due to composition effects. We also use the estimates to predict net union density at the industry level based on the IAB employment subsample for the time period 1985 to 1997. JEL - Klassifikation: J
Quantum engineering of squeezed states for quantum communication and metrology
We report the experimental realization of squeezed quantum states of light,
tailored for new applications in quantum communication and metrology. Squeezed
states in a broad Fourier frequency band down to 1 Hz has been observed for the
first time. Nonclassical properties of light in such a low frequency band is
required for high efficiency quantum information storage in electromagnetically
induced transparency (EIT) media. The states observed also cover the frequency
band of ultra-high precision laser interferometers for gravitational wave
detection and can be used to reach the regime of quantum non-demolition
interferometry. And furthermore, they cover the frequencies of motions of
heavily macroscopic objects and might therefore support the attempts to observe
entanglement in our macroscopic world.Comment: 12 pages, 3 figure
The GEO600 squeezed light source
The next upgrade of the GEO600 gravitational wave detector is scheduled for
2010 and will, in particular, involve the implementation of squeezed light. The
required non-classical light source is assembled on a 1.5m^2 breadboard and
includes a full coherent control system and a diagnostic balanced homodyne
detector. Here, we present the first experimental characterization of this
setup as well as a detailed description of its optical layout. A squeezed
quantum noise of up to 9dB below the shot-noise level was observed in the
detection band between 10Hz and 10kHz. We also present an analysis of the
optical loss in our experiment and provide an estimation of the possible
non-classical sensitivity improvement of the future squeezed light enhanced
GEO600 detector.Comment: 8 pages, 4 figure
Squeezed light at sideband frequencies below 100 kHz from a single OPA
Quantum noise of the electromagnetic field is one of the limiting noise
sources in interferometric gravitational wave detectors. Shifting the spectrum
of squeezed vacuum states downwards into the acoustic band of gravitational
wave detectors is therefore of challenging demand to quantum optics
experiments. We demonstrate a system that produces nonclassical continuous
variable states of light that are squeezed at sideband frequencies below 100
kHz. A single optical parametric amplifier (OPA) is used in an optical noise
cancellation scheme providing squeezed vacuum states with coherent bright phase
modulation sidebands at higher frequencies. The system has been stably locked
for half an hour limited by thermal stability of our laboratory.Comment: 3 pages, 3 figure
Test of Lorentz Symmetry by using a 3He/129Xe Co-Magnetometer
To test Lorentz symmetry we used a 3He/129Xe co-magnetometer. We will give a
short summary of our experimental setup and the results of our latest
measurements. We obtained preliminary results for the equatorial component of
the background field interacting with the spin of the bound neutron: b_n < 3.72
x 10^(-32) GeV (95 C.L.).Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28 - July 2, 201
Crash and Durability of Aluminum and Mixed Steel Aluminum Joints Made by Electromagnetic Pulse Welding
In this paper, results of the research project “Failure behavior of mixed weld joints under multi-axial crash-like and cyclic loads on the example of EMPT sheet metal joints” funded by the German Federal Ministry for Economic Affairs and Energy are presented and discussed. Aluminum and mixed aluminum-steel joints were prepared using electromagnetic pulse technology (EMPT) at PSTproducts GmbH (PST). Investigations on coupon samples were performed under oscillating and monotone (crash) loadings until failure. Based on the coupon tests, parameters for modelling the crash performance were derived, using both a detailed continuum model and an application driven simplified FE-model. The derived FE-modelling concept for crash behavior was validated by comparison of component tests and simulations Durability analysis of the joint specimens was performed combined with FEM analysis, applying the notch stress concept. For the notch stress concept a notch model with a reference radius of rref=0.05 mm was used for the FE-simulations. The endurable notch stresses were compared to reference S-N curves derived for conventional welded samples. The EMPT-results fit well in the scatter band of the conventional laser-welded joints. This is the verification that the notch stress concept can be successfully applied also for EMPT joints
Limit on Lorentz and CPT violation of the bound Neutron Using a Free Precession 3He/129Xe co-magnetometer
We report on the search for Lorentz violating sidereal variations of the
frequency difference of co-located spin-species while the Earth and hence the
laboratory reference frame rotates with respect to a relic background field.
The co-magnetometer used is based on the detection of freely precessing nuclear
spins from polarized 3He and 129Xe gas samples using SQUIDs as low-noise
magnetic flux detectors. As result we can determine the limit for the
equatorial component of the background field interacting with the spin of the
bound neutron to be bn < 3.7 x 10^{-32} GeV (95 C.L.).Comment: 5 pages, 4 figure
Squeezed-field injection for gravitational wave interferometers
In a recent table-top experiment, we demonstrated the compatibility of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal recycling and squeezed-field injection. The interferometer's signal-to-noise ratio was improved by up to 2.8 dB beyond the coherent state's shot-noise. This value was mainly limited by optical losses on the squeezed field. We present a detailed analysis of the optical losses in our experiment and provide an estimation of the possible nonclassical performance of a future squeezed-field enhanced GEO 600 detector
Laser interferometry with translucent and absorbing mechanical oscillators
The sensitivity of laser interferometers can be pushed into regimes that
enable the direct observation of quantum behaviour of mechanical oscillators.
In the past, membranes with subwavelength thickness (thin films) have been
proposed as high-mechanical-quality, low-thermal-noise oscillators. Thin films
from a homogenous material, however, generally show considerable light
transmission accompanied by heating due to light absorption, which typically
reduces the mechanical quality and limits quantum opto-mechanical experiments
in particular at low temperatures. In this work, we experimentally analyze a
Michelson-Sagnac interferometer including a translucent silicon nitride (SiN)
membrane with subwavelength thickness. We find that such an interferometer
provides an operational point being optimally suited for quantum
opto-mechanical experiments with translucent oscillators. In case of a balanced
beam splitter of the interferometer, the membrane can be placed at a node of
the electro-magnetic field, which simultaneously provides lowest absorption and
optimum laser noise rejection at the signal port. We compare the optical and
mechanical model of our interferometer with experimental data and confirm that
the SiN membrane can be coupled to a laser power of the order of one Watt at
1064 nm without significantly degrading the membrane's quality factor of the
order 10^6, at room temperature
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